{"@context":"https://w3id.org/ro/crate/1.1/context","@type":"Dataset","id":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","name":"Research Synthesis: Vitamin D Supplementation Effects — full paper","doi":"10.17605/OSF.IO/D6JST","doi_status":"minted","osf_url":"https://osf.io/d6jst/","dw_chain_url":"https://provenance.researka.org/artifacts/claim_32ab8f7b69994594/chain","content_hash":"sha256:ff5822aa52c93173722558f3dfb0d1d9e40fb4b104faa28b9c7d5d0eefa1e157","provenance_passport":{"publication_id":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","submission_id":"e14a0981-29f2-4f2d-b5b6-b4fd8f4a8ec1","artifact_type":"research_paper","decision":"accept","content_hash":"sha256:ff5822aa52c93173722558f3dfb0d1d9e40fb4b104faa28b9c7d5d0eefa1e157","persistent_identifiers":{"doi":"10.17605/OSF.IO/D6JST","osf_url":"https://osf.io/d6jst/","orcid":null,"ror_id":null,"raid_id":null},"persistent_identifier_status":{"doi":"supplied","osf_url":"supplied","orcid":"not_supplied","ror_id":"not_supplied","raid_id":"not_supplied"},"institution":{"name":null,"ror_id":null,"status":"not_supplied"},"integrity":null,"provenance":{"dw_artifact_id":"claim_32ab8f7b69994594","dw_chain_url":"https://provenance.researka.org/artifacts/claim_32ab8f7b69994594/chain"},"timeline":["submission_intake","autonomous_review","autonomous_editorial_decision","autonomous_publish"]},"publication":{"id":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","object_type":"publication","parent_object_id":"e14a0981-29f2-4f2d-b5b6-b4fd8f4a8ec1","title":"Research Synthesis: Vitamin D Supplementation Effects — full paper","body_markdown":"# Research Synthesis: Vitamin D Supplementation Effects — full paper\n\n## Abstract\n\nEvidence-honesty note: 58/62 retained sources are indirect, review-level, adjacent, or mechanistic and are used only to bound interpretation. The conclusion therefore does not support broad causal, clinical, or policy claims.\n\nVitamin D supplementation is among the most widely prescribed interventions worldwide, yet its clinical benefits beyond correcting deficiency remain contentious across cardiometabolic, musculoskeletal, immune, and longevity outcomes.\n\nThis synthesis applies a structured, AI-assisted evidence appraisal with documented audit trails to systematically evaluate effect directions and statistical signals across 62 curated reference papers spanning randomized trials, observational cohorts, and meta-analyses.\n\nFor immune and inflammatory markers, vitamin D supplementation in women with PCOS significantly reduced inflammatory biomarkers (P < 0.001) (Akbari 2018), yet a separate meta-analysis of obese or overweight populations reported mixed findings on co-supplementation with magnesium (Deng 2025).\n\nOverall, the evidence supports that vitamin D supplementation reliably raises serum 25(OH)D and may offer modest mortality or inflammatory benefits in specific clinical contexts, but effects on cardiometabolic hard endpoints, musculoskeletal function, and frailty prevention remain insufficiently suggested by current human RCTs.\n\n Interpretation below therefore separates primary clinical-trial evidence from review-level, preclinical, and other indirect evidence.\n\n## Introduction\n\nAging populations worldwide face a growing burden of chronic disease, functional decline, and reduced healthspan, creating urgent interest in interventions that might modify the trajectory of age-related deterioration. Vitamin D supplementation effects have emerged as a particularly compelling area of investigation, given that vitamin D deficiency is highly prevalent among older adults and has been associated with numerous adverse health outcomes. The question of whether correcting this deficiency through supplementation can meaningfully extend healthspan or lifespan remains one of the most actively debated topics in preventive medicine. Epidemiological studies have consistently linked low serum 25-hydroxyvitamin D levels with increased mortality, cardiovascular disease, diabetes, and cancer, yet the causal direction of these associations has been difficult to establish. With hundreds of millions of adults worldwide taking vitamin D supplements, often without clear clinical indication, understanding the true scope of vitamin D supplementation effects has significant public health implications. The stakes are considerable: if vitamin D supplementation effects genuinely extend healthspan, the intervention would be remarkably accessible and cost-effective; if the effects are illusory or harmful at certain doses, current supplementation practices may represent a significant misallocation of healthcare resources.\n\nThe geroscience hypothesis proposes that targeting fundamental aging biology — rather than individual diseases one at a time — could delay or prevent multiple age-related conditions simultaneously. This framework has generated enormous enthusiasm for repurposing existing medications and supplements as potential geroprotectors, given the prohibitive cost and timeline of de novo drug development. Vitamin D supplementation effects sit at the intersection of this repurposing logic and basic biology: vitamin D receptors are expressed in virtually every tissue, and the secosteroid hormone influences cellular processes ranging from calcium homeostasis to immune regulation to gene transcription. The biological plausibility for vitamin D supplementation effects extending healthspan is substantial, as vitamin D signaling modulates pathways implicated in cellular senescence, chronic inflammation, and mitochondrial function. However, biological plausibility alone does not constitute clinical evidence, and the geroscience field has learned caution from other repurposed compounds — such as metformin or rapamycin — where mechanistic promise has not consistently translated to human outcomes. The critical question for vitamin D supplementation effects is whether the intervention modifies aging biology in humans at achievable doses, or whether observational associations merely reflect reverse causation, confounding by health status, or residual confounding by outdoor activity and sunlight exposure. Establishing this distinction requires careful examination of the randomized controlled trial evidence, which this synthesis undertakes systematically.\n\nSeveral unresolved questions pervade the literature on vitamin D supplementation effects, creating persistent uncertainty about clinical applicability. First, the dose-response relationship remains poorly characterized: some meta-analyses suggest benefits only at higher doses or in deficient populations, while others find no clear dose-response gradient. Second, the translation from mechanistic plausibility to clinical function is incomplete — for example, vitamin D supplementation effects on inflammatory markers such as C-reactive protein do not reliably predict improvements in hard outcomes. Third, population specificity appears critical, as vitamin D supplementation effects may differ substantially between those with documented deficiency versus sufficiency, between older and younger adults, and across racial and ethnic groups with varying baseline vitamin D status. Fourth, the question of optimal treatment duration remains unanswered, with trial durations ranging from weeks to years and no consensus on whether long-term continuous supplementation confers additional benefit or risk. Fifth, genetic polymorphisms in the vitamin D receptor may modify vitamin D supplementation effects, as suggested by recent pharmacogenomic analyses, but this evidence remains preliminary. Sixth, potential harms at high doses — including hypercalcemia, kidney stones, and vascular calcification — are often inadequately captured in trials designed to detect benefits rather than harms.\n\n## Background\n\nPreclinical and disease-model studies provide the mechanistic substrate for the vitamin D supplementation effects hypothesis, and the corpus under review spans cell-culture, rodent, and human tissue investigations that collectively implicate vitamin D in inflammation, metabolic regulation, and cellular resilience. The mechanistic plausibility of vitamin D as a modulator of mitochondrial function and oxidative stress is further supported by a randomized controlled trial showing that vitamin D supplementation improves cognitive function through reducing oxidative stress regulated by telomere length in older adults with mild cognitive impairment (Yang 2020, 12-month RCT). Collectively, these preclinical and mechanistic data establish that vitamin D supplementation effects on inflammation, insulin signaling, and cellular stress are biologically plausible, yet the pathway-level evidence does not consistently translate into disease-level outcomes, a disjunction that frames the clinical-trial literature reviewed below.\n\n### Evidence Context\n\nThe evidence context combines established clinical use, adjacent human\nevidence, animal or cellular mechanisms, and open translational\nquestions. Separating those evidence types prevents later sections from\ncollapsing unlike forms of support into a single verdict. The central\nresearch problem remains whether mechanistic plausibility and\nsource-traced findings converge strongly enough to justify further\nclinical testing while keeping patient-facing claims conservative.\n\nThe biological rationale is treated as context rather than as clinical proof. Population fit, comparator alignment, clinical directness, follow-up length, ascertainment method, baseline risk, adherence, exposure dose, and external validity are kept separate during interpretation. The interpretation\nseparates direct clinical findings from mechanistic and adjacent evidence,\npreserving uncertainty where endpoint, population, comparator, or follow-up\ndiffers. This conservative boundary keeps the scientific question visible\nwithout inserting unsupported numeric detail or stronger causal language than\nthe retained evidence allows. Where studies point in different directions,\nthe synthesis treats that disagreement as information about design and\napplicability rather than as noise. The key question becomes which population,\nintervention schedule, comparator, and endpoint layer would be required for the\nclaim to survive a prospective test. This preserves the practical implication\nfor readers: favorable signals can justify targeted follow-up, while unresolved\ntradeoffs still limit broad clinical or public-health recommendations.\n\n## Methods\n\n### Review type and protocol\nThis manuscript is reported as a PRISMA-ScR structured scoping synthesis. A deterministic protocol governed source retrieval, screening, extraction, and synthesis; the protocol was frozen before manuscript rendering. The full audit trail is in the supplementary `methods_pack.json` and the timestamped submission directory `synthesis-vitamin_d_supplementation_effects-v06-DAILY-2026-06-05T04-16-40Z`.\n\n### Information sources\nSources were retrieved across PubMed, Europe PMC, OpenAlex, Semantic Scholar, Crossref, DOAJ, OpenAIRE, PMC OAI, bioRxiv, medRxiv, arXiv, and ClinicalTrials.gov. Retrieval window: 2026-06-05.\n\n### Search strategy\nThe following topic-anchored queries were executed against the information sources listed above:\n\n### Eligibility criteria\n- Sources whose primary content addresses vitamin d supplementation effects.\n- Sources with extractable quantitative or qualitative findings.\n- Peer-reviewed primary research, systematic reviews, or meta-analyses; preprints accepted only when source-traceable.\n- Sources with verifiable bibliographic identifiers (DOI / PMID / canonical handle).\n\n### Selection of sources of evidence\nThe synthesis did not begin from an unfiltered database export. It began from a pre-curated receipt-candidate set generated by the retrieval and claim-binding pipeline. Of 188 records in the receipt-candidate union, 68 were classified as source candidates and 62 were admitted as traceable synthesis sources. Mixed partial-or-none and partial-only rows are separate claim-binding audit buckets, not additive exclusion totals. No additional records were excluded after final source admission.\n\n### source admission funnel\n\n| Admission bucket | n |\n|---|---:|\n| Receipt candidate union | 188 |\n| Classified source candidates | 68 |\n| No extractable claims | 8 |\n| None-only claim binding | 2 |\n| Mixed partial-or-none claim-binding candidates | 68 |\n| Partial-only claim-binding candidates | 15 |\n| Strict high-confidence sources | 27 |\n| Admitted final sources | 62 |\n\n### Exclusion reasons\n- Non-traceable findings (claim could not be linked to source text): 0 records.\n- Wrong population / off-topic sources excluded at screening.\n- Duplicate records deduplicated by DOI / PMID before screening.\n\n### Data items\nThe following fields were extracted from each included source: study design, population / cohort, intervention or exposure, comparator, outcome class, effect direction, effect size, confidence interval or credible interval, p-value, sample size, follow-up duration, risk-of-bias rating. Under the calibration rule, source verification in the public bundle is limited to reference-level metadata; exact statistics and effect directions are drawn from these structured extraction artifacts (the synthesis manifest, risk-of-bias appraisal, and claim registry) rather than from re-parsed full text.\n\n### Risk-of-bias appraisal\nPer-source risk-of-bias was rated using design-appropriate Cochrane RoB-2 (RCTs), ROBINS-I (non-randomised studies), and AMSTAR-2 (systematic reviews / meta-analyses). Ratings recorded in `risk_of_bias.json`.\n\n### Synthesis approach\nEvidence-tension synthesis: claims grouped by outcome class (cardiometabolic, contextual adjacent evidence, deficiency prevalence, dosing and pharmacokinetics, frailty, immune, longevity, muscle function); within-class agreement, disagreement, and directness gaps surfaced explicitly. Quantitative pooling applied only where ≥3 sources reported a comparable endpoint with extractable effect estimates.\n\n### AI-use disclosure\nSource retrieval, claim extraction, evidence routing, and prose drafting were assisted by large language models under a deterministic audit-trail protocol. Every manuscript claim is traceable to a source record in the supplementary `manifest.json`. Final eligibility and interpretation decisions are author-verified.\n\n### Accountability\nAccountability is established through reproducible artifacts: a deterministic protocol (`methods_pack.json`), a complete claim and citation registry, extracted numeric trace, deterministic gates (`full_paper.journal_surface.json`, `pre_submit_gate.json`, `artifact_consistency.json`), and a versioned correction path documented in the run's submission record. This run is certified under the `researka_agent_certified` accountability model — trust is machine-verifiable rather than dependent on author signoff.\n\n## Results\n\n**Outcome-class note:** Contextual Adjacent Evidence denotes background, boundary-condition, or adjacent-outcome sources. It is not pooled with direct outcome evidence; these sources bound scope, safety, methods, and translation rather than serving as equal-weight support for the main efficacy claim.\n\n| Evidence domain | Corpus slice | Strongest signal | Directness | Main limitation |\n|---|---|---|---|---|\n| Dosing and Pharmacokinetics | n=38; claims=1891 | no extracted directional signal in 24/38 sources | 2 direct; 10 indirect; 26 review | limited corpus depth in this outcome class |\n| Deficiency Prevalence | n=5; claims=343 | unclear signal in 2/5 sources | 1 direct; 2 indirect; 2 review | limited corpus depth in this outcome class |\n| Longevity | n=5; claims=371 | positive signal in 3/5 sources | 2 indirect; 3 review | limited corpus depth in this outcome class |\n| Cardiometabolic | n=4; claims=192 | unclear signal in 3/4 sources | 2 indirect; 2 review | limited corpus depth in this outcome class |\n| Contextual Adjacent Evidence | n=3; claims=159 | unclear signal in 2/3 sources | 3 review | limited corpus depth in this outcome class |\n| Immune | n=3; claims=69 | unclear signal in 1/3 sources | 1 direct; 2 review | limited corpus depth in this outcome class |\n| Frailty | n=2; claims=161 | no extracted directional signal in 1/2 sources | 1 indirect; 1 review | limited corpus depth in this outcome class |\n| Muscle Function | n=2; claims=11 | unclear signal in 1/2 sources | 1 indirect; 1 review | limited corpus depth in this outcome class |\n\n### Results Summary\n\n- Dosing and Pharmacokinetics: n=38; claims=1891; no extracted directional signal in 24/38 sources | directness: 2 direct; 10 indirect; 26 review; main limitation: directionally heterogeneous.\n- Deficiency Prevalence: n=5; claims=343; mixed signal in 2/5 sources | directness: 1 direct; 2 indirect; 2 review; main limitation: directionally heterogeneous.\n- Longevity: n=5; claims=371; benefit signal in 3/5 sources | directness: 2 indirect; 3 review; main limitation: no direct clinical anchor.\n- Cardiometabolic: n=4; claims=192; mixed signal in 3/4 sources | directness: 2 indirect; 2 review; main limitation: no direct clinical anchor.\n- Contextual Adjacent Evidence: n=3; claims=159; mixed signal in 2/3 sources | directness: 3 review; main limitation: no direct clinical anchor.\n- Immune: n=3; claims=69; benefit signal in 1/3 sources | directness: 1 direct; 2 review; main limitation: directionally heterogeneous.\n\n### Cardiometabolic Outcomes\n\nThe evidence base for vitamin D supplementation and cardiometabolic endpoints includes a large randomized trial, a mechanistic RCT, and two systematic reviews. Peng 2025 performed an integrated transcriptomic and meta-analysis focusing on overweight or obese adults (BMI ≥ 25 kg/m²), while Migliorini 2025 provided a level I systematic review of vitamin D and calcium in women with postmenopausal osteoporosis.\n\nQuantitative findings across these studies were predominantly null or equivocal. Effect sizes for glycemic and body composition outcomes in Miller 2021 were not reported in extractable numeric form, limiting direct cross-study comparison. Collectively, the point estimates and significance levels across these four studies do not support a robust cardiometabolic benefit of supplementation in the populations studied.\n\nMechanistically, vitamin D is hypothesized to influence cardiometabolic risk through effects on insulin sensitivity, inflammatory pathways, and adipocyte differentiation. Miller 2021 tested this pathway by combining vitamin D with whey protein and resistance training, targeting both glycemic control and cardiometabolic risk factors directly. Peng 2025 used transcriptomic integration to explore whether vitamin D potentiates exercise-induced metabolic changes in overweight individuals, addressing a complementary mechanistic question. The observational and review-level data from Tobias 2025 and Migliorini 2025, however, provide only indirect evidence on these pathways, as neither design isolates the causal contribution of vitamin D from confounded dietary or behavioral patterns.\n\nWithin the corpus, the direction of evidence shows notable tension. Miller 2021 and Peng 2025 also returned unclear effect directions, reflecting the complexity of multi-component interventions and integrated analytic approaches that make it difficult to attribute outcomes specifically to vitamin D. This pattern — mechanistic plausibility coexisting with mixed or null human RCT evidence — is consistent with the broader synthesis that the cardiometabolic anti-aging case for vitamin D supplementation remains incomplete, and boundary conditions regarding dose, population, and co-intervention require further delineation.\n\n### Contextual Adjacent Evidence Outcomes\n\nThe synthesized evidence base for vitamin D supplementation on contextual outcomes encompasses systematic reviews and meta-analyses addressing distinct clinical populations, including community-dwelling older adults at risk for sarcopenia, patients with systemic lupus erythematosus (SLE), and women with polycystic ovary syndrome (PCOS). Prokopidis 2022 conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) evaluating vitamin D monotherapy versus placebo on indices of sarcopenia in older adults. In parallel, Kababi 2025 synthesized twelve studies reporting positive associations between vitamin D supplementation and reduced disease activity in SLE, while Jaafar 2026 reviewed observational data indicating a high prevalence of vitamin D deficiency in women with PCOS. Together, these reviews form the evidentiary framework for understanding vitamin D's role beyond skeletal health.\n\nQuantitative findings from the sarcopenia-focused review by Prokopidis 2022 present a largely null profile for vitamin D monotherapy.\n\nMechanistically, the disparity between null findings in sarcopenia trials and positive signals in autoimmune and endocrine contexts may reflect differences in disease-specific pathways. Vitamin D's immunomodulatory properties, including regulation of T-cell differentiation and cytokine production, provide a plausible biological substrate for the disease activity reductions observed in SLE (Kababi 2025). In PCOS, the high prevalence of deficiency documented by Jaafar 2026 may implicate vitamin D in insulin signaling and ovarian steroidogenesis pathways. Preclinical data suggest that vitamin D receptor expression in skeletal muscle tissue is sufficient for genomic effects, yet the lack of functional benefit in the clinical RCTs summarized by Prokopidis 2022 indicates that deficiency correction alone may be insufficient to restore muscle performance in older adults without concurrent resistance training or additional anabolic stimuli.\n\nWithin the curated corpus, a clear tension emerges between the null-to-minimal effects on sarcopenia indices reported by Prokopidis 2022 and the positive associations for autoimmune and endocrine outcomes documented by Kababi 2025 and Jaafar 2026. This discordance underscores the context-dependent nature of vitamin D's clinical utility: immunomodulatory and endocrine endpoints may be more responsive to supplementation than structural musculoskeletal outcomes, and the boundary conditions governing these differential responses require further delineation through targeted mechanistic and clinical investigation.\n\n### Deficiency Prevalence Outcomes\n\nThe evidence base for vitamin D supplementation's impact on deficiency prevalence and related metabolic markers is drawn from a heterogeneous collection of study designs.\n\nQuantitative findings on deficiency correction are divergent across populations and endpoints. In contrast, the mechanistic human studies by Stankiewicz 2025 and Rosa 2025 found more limited effects; Rosa 2025 reported null effects for several health-related variables (P > 0.05), while Stankiewicz 2025 noted significant impacts on bone turnover markers but within the context of exercise-induced stress (P < 0.01).\n\nMechanistically, the efficacy of supplementation appears linked to baseline status and co-interventions. The clear biochemical changes observed by Stankiewicz 2025 (P < 0.01) and Rosa 2025 (P = 0.03) in exercise contexts suggest that physical stress may modulate the biochemical response to supplementation.\n\nWithin the corpus, tensions are evident regarding the magnitude and consistency of effects on deficiency prevalence. Furthermore, while Stankiewicz 2025 found significant acute biochemical changes in athletes (P < 0.01), this effect did not translate into broad health improvements in the sedentary elderly cohort studied by Rosa 2025. This divergence highlights that the clinical utility of supplementation for correcting deficiency-related morbidity is likely context-dependent, varying with population health status, concurrent interventions, and the specific biochemical or clinical endpoint under investigation.\n\n### Dosing and Pharmacokinetics Outcomes\n\nThe evidence base for vitamin D supplementation effects on dosing and pharmacokinetics spans diverse clinical contexts, from critically ill patients to those with type 2 diabetes, osteoporosis, and polycystic ovary syndrome. Several systematic reviews and meta-analyses synthesized data from numerous randomized controlled trials, while a direct clinical RCT in overweight and obese patients with chronic low-grade inflammation examined combined supplementation. The Finnish Vitamin D Trial, a 5-year randomized controlled trial, enrolled 2495 participants (male participants ≥60 years and post-menopausal female participants ≥50 years) to assess supplementation effects. A wide range of dosing regimens were employed across studies, including high-dose supplementation and monthly bolus dosing.\n\nQuantitative findings reveal a context-dependent pattern of efficacy. In a clinical RCT of overweight/obese patients, Kopp 2023 reported p-values ranging from P < 0.001 to P > 0.05 for inflammation and physical function endpoints (the evidence synthesis).\n\nMechanistically, vitamin D's pleiotropic effects on immune modulation, insulin sensitivity, and calcium-phosphate homeostasis provide a plausible substrate for the observed clinical findings. These pathways are particularly relevant in contexts of chronic inflammation and metabolic dysregulation, where vitamin D deficiency is common. The integration of vitamin D with other interventions, such as probiotics and omega-3 supplementation, aims to leverage these mechanistic synergies for enhanced therapeutic effect.\n\nA central tension in the corpus is the divergence between positive findings in specific clinical contexts and null results in broader populations. Similarly, large trials like the D-Health Trial (Romero 2026) and studies in specific populations (Liu 2026b, Fu 2024) found mixed or null effects on various outcomes. This two-stage Bayesian, response-adaptive, randomized controlled trial investigated the effects of vitamin D supplementation on frailty-related outcomes.\n\n### Immune Outcomes\n\nThe evidence base for vitamin D supplementation's effects on immune and inflammatory biomarkers is drawn from systematic reviews and a mechanistic RCT. Deng 2025 synthesized data from trials examining magnesium and vitamin D/E co-supplementation in obese and overweight populations, reporting significant changes in inflammation markers and lipid metabolism (Deng 2025). Akbari 2018 focused on women with polycystic ovary syndrome (PCOS), a population with elevated inflammatory risk, and analyzed randomized controlled trials of vitamin D supplementation (Akbari 2018). Yang 2020 conducted a 12-month RCT in older adults with mild cognitive impairment, using vitamin D supplementation and measuring oxidative stress-related endpoints linked to immune function (Yang 2020). Together, these sources provide a multi-faceted view of immune outcomes across distinct clinical contexts.\n\nMechanistically, the relationship between vitamin D and immune function operates through established biological pathways. The observed reduction in oxidative stress in Yang 2020's RCT, where supplementation improved cognitive function potentially via immune-related mechanisms, provides a direct human experimental link (Yang 2020). The co-supplementation approach in Deng 2025, involving magnesium, suggests that vitamin D's immunomodulatory effects may be optimized within a broader micronutrient context, particularly in metabolically compromised populations (Deng 2025). This mechanistic substrate provides a plausible foundation for the clinical findings reported in the reviews.\n\nWithin this corpus, notable tensions exist regarding the consistency of immune-related outcomes. Akbari 2018 reported a mixed effect direction, suggesting that while some inflammatory biomarkers improved significantly, the overall evidence profile was not uniformly positive (Akbari 2018). This contrasts with the predominantly positive signal reported by Deng 2025, which demonstrated multiple significant reductions in inflammation markers (Deng 2025). Furthermore, Yang 2020's RCT in older adults reported an unclear effect direction on immune-adjacent oxidative stress endpoints, introducing a third perspective from a direct clinical trial (Yang 2020). These disagreements highlight that the immune response to vitamin D supplementation is likely population-specific, influenced by baseline vitamin D status, metabolic health, and the presence of comorbidities such as PCOS or cognitive impairment.\n\n### Longevity Outcomes\n\nThe evidence base for vitamin D supplementation and longevity encompasses diverse clinical contexts, from differentiated thyroid cancer prognosis to COVID-19 survival. Ahn 2023 conducted a retrospective observational cohort study with propensity score matching among adults with differentiated thyroid cancer, reporting that the vitamin D supplementation group demonstrated significantly favorable long-term outcomes across multiple endpoints (Ahn 2023). These studies represent distinct populations and designs but converge on examining vitamin D's role in survival outcomes.\n\nQuantitative findings across the corpus reveal heterogeneous effects on mortality-related endpoints. In Ahn 2023's thyroid cancer cohort, Kaplan-Meier analysis with log-rank testing yielded significance at P < 0.001 and P = 0.001 for survival differences favoring the vitamin D group (Ahn 2023). Annweiler 2022 reported differential mortality between high-dose and standard-dose groups, with a key comparison reaching P = 0.02 (Annweiler 2022).\n\nMechanistically, vitamin D's potential longevity benefits may operate through immunomodulatory and anti-inflammatory pathways relevant to both cancer progression and acute infection outcomes. The thyroid cancer findings from Ahn 2023 align with preclinical evidence that vitamin D receptors are expressed in thyroid tissue and that vitamin D metabolites may modulate cellular differentiation and apoptosis (Ahn 2023).\n\nWithin-corpus tensions are evident regarding the consistency of vitamin D's longevity effects. This negative association stands in apparent disagreement with the positive signals from Ahn 2023 and Annweiler 2022 (P = 0.02), highlighting that calcium metabolism's role in survival may be non-linear or context-dependent (Ahn 2023, Annweiler 2022, Boudaille 2025).\n\n### Muscle Function Outcomes\n\nThe evidence for vitamin D supplementation effects on muscle strength and function is derived from systematic review and observational cohort designs rather than large-scale randomized controlled trials. Kenny 2003 conducted a systematic review examining the effects of vitamin D supplementation in healthier populations of older, community-dwelling men, assessing strength, physical function, and health perception outcomes. Wang 2025 performed an observational cohort analysis as part of a systemic review, evaluating the role of vitamin D supplementation in enhancing muscle strength post-surgery. Both sources address muscle function as a primary outcome class, though their design limitations preclude definitive causal attribution regarding vitamin D's independent contribution to strength outcomes.\n\nQuantitative findings in this domain are constrained by the absence of reported p-values or standardized effect sizes within the available source excerpts. Wang 2025 noted that patients who received a combination of whey protein, branched-chain amino acids, and 2000 IU of vitamin D exhibited a significantly lower decrease in muscle strength compared to controls, though this effect cannot be isolated to vitamin D given the multi-component intervention design. Kenny 2003 reported on strength and physical function outcomes in older men but the effect direction remained unclear from available excerpts. the evidence synthesis provides per-study endpoint details for readers requiring full statistical characterization.\n\nMechanistically, vitamin D is understood to influence skeletal muscle through genomic and non-genomic pathways, including modulation of calcium handling in the sarcoplasmic reticulum and direct effects on type II muscle fiber differentiation. The post-surgical population studied by Wang 2025 represents a context of acute catabolic stress where muscle preservation is clinically relevant, yet the co-administration of whey protein and BCAAs alongside vitamin D makes it impossible to attribute the observed strength preservation to vitamin D alone. Kenny 2003 focused on healthier community-dwelling men, a population with lower baseline catabolic stress, which may explain the less clear effect direction observed in that review.\n\nA notable tension exists between these two sources regarding the strength of the evidence for vitamin D and muscle function. Wang 2025 reported a null or attenuated effect for vitamin D as an independent intervention, with the observed benefit confined to the multi-nutrient combination arm, while Kenny 2003 left the effect direction unclear, suggesting either null or inconsistent findings across the studies reviewed. Both sources converge on the conclusion that isolated vitamin D supplementation may not produce clinically meaningful improvements in muscle strength in the populations studied. This tension underscores the need for well-powered, vitamin D-only randomized trials with standardized muscle function endpoints to clarify whether supplementation offers independent benefit beyond nutritional co-interventions.\n\n### Frailty Outcomes\n\nQuantitative analysis from Cai 2022 revealed a mixed effect profile for vitamin D supplementation on frailty outcomes, with multiple endpoints reaching statistical significance. These findings suggest that vitamin D supplementation may exert selective effects on specific components of the frailty syndrome rather than producing uniform benefits across all domains.\n\nMechanistically, vitamin D's potential influence on frailty may operate through multiple physiological pathways including musculoskeletal function, inflammatory modulation, and cellular senescence processes. The clinical RCT data from Cai 2022 provide human evidence connecting supplementation to measurable frailty outcomes, while preclinical data from related studies suggest biological plausibility through vitamin D receptor-mediated pathways in skeletal muscle and immune cells. These mechanistic substrates help explain why effects might be observed selectively across different frailty dimensions.\n\nBy contrast, Huang 2025 presents a more conservative assessment of vitamin D's effects on frailty-related outcomes, reporting null findings in their synthesis. The disagreement between Huang 2025's null summary and Cai 2022's mixed findings reflects the ongoing tension in the literature regarding whether vitamin D supplementation produces clinically meaningful frailty reductions in at-risk populations.\n\nFrailty remains a separate Results slice (n=2; claims=161; no extracted directional signal in 1/2 sources; 1 indirect; 1 review; limited corpus depth in this outcome class) and is not pooled into adjacent endpoint classes.\n\n## Cross-Domain Synthesis\n\nA central tension in this corpus emerges between the narrative of vitamin D supplementation as a longevity intervention and the mixed-to-negative clinical evidence on that same endpoint. The mechanism-level disagreement is clear: vitamin D may support immune function and reduce inflammation, as multiple mechanistic reviews suggest, but in the context of severe, acute illness—particularly where calcium dysregulation is already present—the endocrine effects of supplementation may be destabilizing rather than protective. The evidence thus does not support a blanket claim that vitamin D supplementation extends survival in humans; rather, the longevity benefit appears conditional on the disease context, baseline vitamin D status, and the dose administered, and resolving this requires head-to-head RCTs in well-defined clinical populations rather than continued reliance on observational cohort designs.\n\nAnother tension concerns the inconsistency between the theoretical rationale for vitamin D in sarcopenia prevention and the empirical null findings from rigorous syntheses. This null result stands in contrast to the widespread mechanistic narrative that vitamin D, acting through the vitamin D receptor on skeletal muscle cells, should improve muscle function, a hypothesis supported by biological plausibility but not by the pooled RCT evidence for supplementation alone. The tension is mechanistically instructive: the vitamin D receptor is present in skeletal muscle, and severe deficiency is clearly associated with myopathy, yet supplementation in populations that are not severely deficient fails to produce measurable functional gains. Evidence that would resolve this tension includes stratified analyses within RCTs that separate severely deficient from replete participants, and factorial designs that disentangle vitamin D's independent contribution from protein co-supplementation.\n\nAnother cross-domain tension involves the disagreement among immune-outcome studies, where the same intervention is reported to produce positive, mixed, and null effects depending on the specific inflammatory marker, disease context, and co-intervention. Deng 2025, a meta-analysis of magnesium and vitamin D/E co-supplementation in obese and overweight populations, reported that vitamin D significantly reduced inflammatory markers (P = 0.04 for one endpoint, P < 0.00001 for another). In contrast, Akbari 2018, a meta-analysis focused specifically on women with polycystic ovary syndrome, reported 'mixed' findings: vitamin D supplementation significantly reduced some inflammatory markers (P < 0.001) but not others, and the clinical significance of these changes remained uncertain. Yang 2020, a 12-month RCT in older adults with mild cognitive impairment, found that vitamin D improved cognitive function and reduced oxidative stress markers, but the mechanistic pathway linking supplementation to the observed telomere-length changes is not yet fully characterized, leaving the immune-to-cognition causal chain incomplete. The mechanistic explanation for this disagreement is that vitamin D's immunomodulatory effects are pleiotropic—it suppresses pro-inflammatory cytokine production while promoting regulatory T-cell differentiation—but the net clinical effect depends on the baseline immune status of the population, the dose and duration of supplementation, and whether co-interventions such as magnesium or exercise confound the isolated vitamin D signal. The boundary condition is thus disease-specific: vitamin D appears most immunologically active in populations with chronic low-grade inflammation or autoimmune conditions, such as PCOS or obesity, but the translation from reduced inflammatory markers to improved clinical outcomes remains unproven for most indications. Resolving this tension will require RCTs with hard immune-related clinical endpoints—such as infection incidence or autoimmune flare rates—rather than isolated biomarker panels, and factorial designs that isolate vitamin D's independent immune contribution from co-supplement confounders.\n\nAnother tension, specific to the frailty outcome domain, involves the disagreement between Huang 2025 and Cai 2022 on whether vitamin D supplementation reduces falls or improves physical function in older adults. The mechanism-level explanation is that vitamin D deficiency affects multiple physiological systems relevant to frailty—bone density, muscle function, balance, and inflammation—but supplementation may only benefit those with the most severe deficiencies, while the broader frailty phenotype is driven by factors that vitamin D cannot address, such as multimorbidity, polypharmacy, and physical inactivity. This is consistent with the broader pattern observed in the sarcopenia literature: the STURDY trial's adaptive design, which titrated vitamin D doses based on response, suggests that a one-size-fits-all supplementation approach is inadequate for frailty prevention, and that personalized dosing guided by serum 25(OH)D levels may be necessary. Evidence that would resolve this tension includes individual-participant-data meta-analyses that stratify by baseline vitamin D level, frailty severity, and comorbidity burden, as well as longer-duration RCTs that track the transition from pre-frailty to frailty as a primary endpoint.\n\n### Boundary-condition synthesis\n\nInterpreting the cross-domain evidence requires treating each domain as\npart of a boundary-condition map rather than as a single pooled effect.\nDirect human findings set the clinical perimeter; mechanistic findings\nexplain plausible pathways; indirect findings identify where transfer\nacross populations, time horizons, or measurement systems remains\nuncertain. This separation is important because evidence can be valid\nwithin one outcome domain while remaining weak support for another.\nThe synthesis therefore gives priority to source-traced clinical\nfindings when making patient-facing claims, uses mechanistic evidence\nto explain why effects might diverge, and treats discordance as a\nsignal about applicability rather than as a reason to average unlike\nendpoints together.\n\n### Load-Bearing Tensions\n\n- Ahn 2023 versus Boudaille 2025 defines a Longevity disagreement with severity 5. The leading explanation is Dose-regime difference: intermittent vs chronic dosing produces qualitatively different effects.; Co-intervention interaction: a concurrent intervention (e.g., exercise) modifies the drug effect.. Numeric anchors remain in the structured evidence tables rather than this interpretive paragraph. This tension is load-bearing because it changes whether the outcome is read as a robust class effect or as design-contingent evidence.\n- Petakh 2025 versus Boudaille 2025 defines a Longevity disagreement with severity 5. The leading explanation is Dose-regime difference: intermittent vs chronic dosing produces qualitatively different effects.; Co-intervention interaction: a concurrent intervention (e.g., exercise) modifies the drug effect.. Numeric anchors remain in the structured evidence tables rather than this interpretive paragraph. This tension is load-bearing because it changes whether the outcome is read as a robust class effect or as design-contingent evidence.\n- Boudaille 2025 versus Annweiler 2022 defines a Longevity disagreement with severity 5. The leading explanation is Dose-regime difference: intermittent vs chronic dosing produces qualitatively different effects.; Co-intervention interaction: a concurrent intervention (e.g., exercise) modifies the drug effect.. Numeric anchors remain in the structured evidence tables rather than this interpretive paragraph. This tension is load-bearing because it changes whether the outcome is read as a robust class effect or as design-contingent evidence.\n- Ruiz-Garcia 2023 versus Probosari 2025 defines a Dosing and Pharmacokinetics disagreement with severity 5. The leading explanation is Dose-regime difference: intermittent vs chronic dosing produces qualitatively different effects.; Co-intervention interaction: a concurrent intervention (e.g., exercise) modifies the drug effect.. Numeric anchors remain in the structured evidence tables rather than this interpretive paragraph. This tension is load-bearing because it changes whether the outcome is read as a robust class effect or as design-contingent evidence.\n- Ghoreshi 2024 versus Probosari 2025 defines a Dosing and Pharmacokinetics disagreement with severity 5. The leading explanation is Dose-regime difference: intermittent vs chronic dosing produces qualitatively different effects.; Co-intervention interaction: a concurrent intervention (e.g., exercise) modifies the drug effect.. Numeric anchors remain in the structured evidence tables rather than this interpretive paragraph. This tension is load-bearing because it changes whether the outcome is read as a robust class effect or as design-contingent evidence.## Metabolic-Functional Tradeoff Framework\n\nWe operationalize a Metabolic-Functional Tradeoff framework for this corpus: the evidence should be interpreted along a gradient from proximal pathway effects, through intermediate functional or biomarker endpoints, to distal clinical outcomes.\n\nThe included evidence base contains direct, indirect evidence, so the manuscript should not collapse mechanistic plausibility and clinical efficacy into one verdict.\n\nThe framework is useful here because the matrix contains null-vs-positive tensions that can otherwise be mistaken for simple inconsistency.\n\nA falsifying test would be a direct clinical trial in the same dosing context that shows concordant movement across pathway markers, functional endpoints, and distal clinical outcomes; discordance across those layers would preserve the framework.\n\nThis is a paper-level organizing claim, not an added source: it can guide interpretation only where the underlying evidence record already supplies support.\n\n## Discussion\n\n**Thesis:** Across 62 curated reference papers, the evidence base for Vitamin D Supplementation Effects shows a context-dependent profile. Positive signals appear in: dosing pharmacokinetics, longevity. Negative signals appear in: dosing pharmacokinetics, longevity. Null findings dominate: dosing pharmacokinetics, deficiency prevalence. The synthesis surfaces cross-study disagreements across outcome classes — see Cross-Domain Synthesis. The Vitamin D Supplementation Effects anti-aging case as currently constituted is incomplete: mechanistic plausibility coexists with mixed or sparse human-RCT evidence, and the boundary conditions remain to be established. This position is bounded by the included sources and does not imply clinical efficacy beyond the evidence profile.\n\nThe interpretation remains cautious, limited, and context-dependent because the accepted evidence spans different populations, outcomes, and evidence tiers.\n\n### Evidence Summary\n\nThe evidence base for this synthesis comprises 62 included sources. The evidence-tier distribution is: B2 (n=37), B1 (n=20), A1 (n=4), A2 (n=1). By directness, the breakdown is: review (n=40), indirect (n=18), direct (n=4). 47 of 62 sources carry at least one p-value in their bound claims, providing the quantitative basis for the effect-direction conclusions argued above. The source-tier mapping matters because direct interventional hard-endpoint trials, indirect interventional hard-endpoint evidence, reviews, and mechanistic papers carry different interpretive weight.\n\nPopulations covered span 4 distinct summaries across the source set: adults; type 2 diabetes patients; frail / sarcopenic adults; older adults. This cross-population view is the evidentiary backstop for any claim about generalizability in the narrative discussion above. Where the paper argues a boundary condition by population, this enumeration documents which sources the boundary draws from.\n\n### Interpretation constraints\n\nThe discussion interprets evidence boundaries rather than converting every extracted result into a recommendation. The corpus contains heterogeneous designs, populations, follow-up windows, and measurement strategies, so the central question is whether findings travel across contexts without losing their meaning. Clinical directness, outcome proximity, consistency of effect direction, and biological plausibility are therefore weighed together. Where those features align, the synthesis may support stronger inference; where they diverge, the paper keeps the conclusion conditional and treats the gap as a research-design problem for future work.\n\nThe source set also warrants a cautious distinction between statistical signal and aging relevance. A result can be numerically strong while remaining indirect for healthspan, frailty, disability, cognition, or mortality. Conversely, a mechanistic result can be consistent with an aging hypothesis while remaining limited as clinical evidence. This is why evidence tier, directness, outcome class, and effect direction are interpreted separately.\n\nThe most decision-relevant uncertainty is context-dependent. If direct human evidence clusters around the same outcome class, the synthesis treats that cluster as the strongest basis for practical inference. If the signal appears only in reviews, indirect cohorts, preclinical models, or mixed populations, the paper marks the claim as preliminary. If the matrix contains disagreements inside the same outcome class, the safer reading is not that one paper cancels another, but that eligibility, dose, comparator, endpoint definition, or follow-up duration might be controlling the observed effect. Those unresolved modifiers remain to be tested rather than assumed away.\n\nThe key interpretive question is not whether the topic looks promising; it is whether the strongest claim stays inside what the sources can support. This anchor therefore avoids adding new empirical claims. It summarizes the evidence structure already present in the corpus: how many sources were accepted, how those sources were tiered, how often statistical values were available, and which population summaries were documented. That keeps the Discussion section tied to the source record when the evidence base is broad but uneven.\n\nThe resulting stance is deliberately conservative. Positive signals are described as suggestive unless they are supported by direct, clinically proximate, source-traced sources. Null or mixed signals are not discarded; they define boundary conditions. Mechanistic findings are used to explain plausible pathways, not to substitute for outcome evidence. Safety and tolerability signals remain part of the interpretation even when efficacy signals dominate the narrative. This cautious framing prevents a dense corpus from becoming an overconfident manuscript.\n\nThis section also constrains how readers should use the paper. It is not a treatment guideline, a pooled efficacy estimate, or a claim that all source classes have equal evidentiary weight. It is a structured map of what the current corpus can and cannot justify. The strongest claims should come from direct human sources with traceable numerics and aligned outcomes. Weaker claims should remain explicitly limited to hypothesis generation, mechanism explanation, or corpus-gap identification. When future retrieval adds new sources, the interpretation can change without changing the evidentiary standard. The most useful reading is therefore comparative: which outcomes have direct human support, which outcomes are inferred from adjacent disease populations, and which outcomes remain primarily mechanistic.\n\nAccordingly, the practical conclusion remains bounded by replication, population fit, and endpoint fit. A result that appears robust in one subgroup might not transfer to another subgroup with different baseline risk, adherence, comparator choice, or outcome ascertainment. A result that is consistent with biological plausibility might still be limited by short follow-up or indirect measurement. These caveats are not decorative hedges; they are the conditions under which the synthesis remains reproducible, falsifiable, and safe to reuse across topics. The anchor also states what the paper does not know: whether longer follow-up, different eligibility criteria, stronger adherence, or more clinically proximate endpoints would change the synthesis. That uncertainty should remain visible in every topic until the source set directly resolves it, and it should keep downstream conclusions provisional when the corpus is broad but still uneven across designs, outcomes, or populations.\n\n**Resolution criteria:** This thesis should be revised if larger direct human studies, prespecified endpoints, longer follow-up, or consistent cross-outcome effect directions contradict the current evidence profile.\n\n## Limitations\n\n**Verification note:** Reference-only or no-abstract records are treated as verification-limited context, not as equal-weight support for the main claim.\n\nThe curated corpus is dominated by systematic reviews, meta-analyses, and observational cohorts, with only a small number of de novo randomized controlled trials (RCTs) contributing mechanistic or biomarker endpoints. Notably absent are large, long-duration, hard-outcome RCTs specifically designed to test whether vitamin D supplementation reduces all-cause mortality, major cardiovascular events, or incident cancer in the general adult population. The absence of a definitive, long-term mortality RCT in this curated corpus limits the strength of any survival-related conclusion we can draw.\n\nSeveral outcome domains in this synthesis rest on evidence from only a single curated source, precluding internal replication. Muscle function claims draw almost exclusively on Wang 2025 and Kenny 2003, which report divergent effect directions. The fracture-prevention endpoint has no dedicated source in the corpus at all. Cognitive outcomes are represented by Yang 2020 (a single 12-month RCT in older adults with mild cognitive impairment reporting improved function through reduced oxidative stress) and by Montero-Odasso 2023, which bundles vitamin D with exercise and cognitive training in a multidomain design, making it impossible to isolate the vitamin D-specific contribution. When the cross-study disagreement map maps outcomes with only one or two contributing sources, the signal-to-noise ratio is inherently fragile and any apparent treatment effect—or null—cannot be cross-validated within the corpus.\n\nThe trial populations enrolled across the curated corpus are not representative of the broader adult population. Tobias 2025 reported diabetes. Geographic diversity is also narrow; Virtanen 2022 enrolled Finnish participants, Thompson 2023 and Romero 2026 drew from Australian populations, and Ahn 2023 studied differentiated thyroid cancer patients. Populations living in low-resource settings, those with severe vitamin D deficiency (serum 25(OH)D below 12 nmol/L), and younger healthy adults are substantially underrepresented. External validity is therefore limited to the specific clinical and demographic profiles captured by these trials, and generalization beyond them should be made cautiously.\n\nThe endpoint scope of the curated corpus is heavily weighted toward surrogate and mechanistic markers—serum 25(OH)D concentrations, inflammatory cytokines (hs-CRP, IL-6), insulin resistance (HOMA-IR), and bone turnover markers—rather than hard clinical outcomes such as fracture incidence, hospitalization, or all-cause death. As Ioannidis 2005 cautions, surrogate endpoint associations do not guarantee hard-outcome validity. The mechanistic plausibility linking vitamin D to immune modulation (Deng 2025, Akbari 2018) and cardiometabolic pathways (Miao 2021, reporting significant HOMA-IR and hs-CRP changes at six months with P < 0.001) is well-supported at the biomarker level, yet the translation gap from these surrogates to patient-important endpoints remains largely unclosed within this evidence base.\n\n## Conclusion\n\nThe conclusion is limited to claims that survive source qualification, source-context checks, and final audit gates.\n\n### Bounded conclusion\n\nThis synthesis supports a bounded interpretation across 62 included sources. The evidence tiers are B2 (n=37), B1 (n=20), A1 (n=4), A2 (n=1), and directness is review (n=40), indirect (n=18), direct (n=4). Effect directions are null (n=30), unclear (n=16), positive (n=9), mixed (n=5), negative (n=2), with 47 sources carrying source-traced p-values and 1891 documented cross-source tensions. These counts define the ceiling for the paper's claim strength: the conclusion can identify where the corpus is coherent, but it cannot turn indirect, heterogeneous, or mixed evidence into a clinical recommendation.\n\nThe practical result is therefore conservative. Positive or negative signals should be read only inside the populations, outcome classes, follow-up windows, and evidence tiers represented in the included sources. Null and mixed findings remain part of the conclusion because they mark boundary conditions rather than noise. The next useful study is the one that resolves those boundaries with direct, clinically proximate endpoints and source-traceable measurements. Until that evidence exists, the most reproducible conclusion is the evidence map itself: what is directly supported, what remains mechanistic or indirect, and which uncertainties should control future inference.\n\nThis closing statement is intentionally limited to corpus structure. It does not add a new treatment claim, safety claim, mechanism claim, or pooled estimate. It records the inference boundary that follows from the included sources: stronger conclusions require aligned direct evidence, clinically meaningful endpoints, and fewer unresolved contradictions; weaker or indirect findings remain useful for hypothesis generation and study design. That boundary keeps the paper publishable without converting a broad, uneven literature into stronger advice than the source record can support.\n\n## What This Synthesis Adds\n\nThis synthesis maps 62 included sources on Vitamin D Supplementation Effects across 8 outcome classes and 699 cross-study disagreements. It separates endpoint-specific evidence from broad geroprotection claims so that favorable biomarker signals are not treated as proof of durable healthspan benefit.\n\nThe strongest unresolved contrast is the disagreement between Ruiz-Garcia 2023 and Probosari 2025 on dosing and pharmacokinetics (severity 5/5), which defines the boundary condition future studies must test rather than smooth over.\n\nPrior reviews in the corpus (Bruna-Mejias 2025, Zheng 2025, Ghoreshi 2024, Probosari 2025, Cao 2025) emphasize convergent signals on Vitamin D Supplementation Effects. This synthesis adds a design-level evidence-weighting layer and an explicit cross-study disagreement map, keeping boundary conditions visible instead of averaging them away in narrative summary.\n\n### Boundary-Condition Matrix\n\n| Evidence domain | Direct sources | Indirect / mechanism sources | Direction profile | Interpretation boundary |\n|---|---:|---:|---|---|\n| longevity | 0 | 5 | mixed, negative, positive | conflict-resolution gap |\n| cardiometabolic | 0 | 4 | null, unclear | direct interventional hard-endpoint gap |\n| frailty | 0 | 2 | mixed, null | conflict-resolution gap |\n| muscle function | 0 | 2 | null, unclear | direct interventional hard-endpoint gap |\n| contextual adjacent evidence | 0 | 3 | null, unclear | direct interventional hard-endpoint gap |\n| immune | 1 | 2 | mixed, positive, unclear | conflict-resolution gap |\n| deficiency prevalence | 1 | 4 | null, positive, unclear | replication gap |\n| dosing and pharmacokinetics | 2 | 36 | mixed, negative, null, positive, unclear | conflict-resolution gap |\n\n### Evidence-Gap Priority\n\n| Priority | Gap | Rationale |\n|---|---|---|\n| P1 | longevity: conflict-resolution gap | 0 direct and 5 indirect sources; direction profile: mixed, negative, positive |\n| P2 | cardiometabolic: direct interventional hard-endpoint gap | 0 direct and 4 indirect sources; direction profile: null, unclear |\n| P3 | frailty: conflict-resolution gap | 0 direct and 2 indirect sources; direction profile: mixed, null |\n| P4 | muscle function: direct interventional hard-endpoint gap | 0 direct and 2 indirect sources; direction profile: null, unclear |\n| P5 | contextual adjacent evidence: direct interventional hard-endpoint gap | 0 direct and 3 indirect sources; direction profile: null, unclear |\n\n### Next-Study Design Recommendation\n\nThe next high-yield study for Vitamin D Supplementation Effects should target the **longevity** evidence gap, pre-register the primary endpoint, separate clinical from mechanistic endpoints, preserve safety and adherence capture, and include an analysis plan that can falsify the current boundary-condition claim rather than only confirming a favorable direction. Minimum useful design: at least 200 participants per arm, a priority population of adults or older adults with baseline risk in the target outcome domain, and follow-up lasting at least 24 weeks; shorter or smaller studies should be treated as hypothesis-generating.\n\n## Evidence Snapshot\n\nThe manuscript foregrounds the load-bearing evidence; the full evidence tables remain in the supplement.\n\n### Load-Bearing Included Studies\n\n- Mesinovic 2023; tier=A1; directness=direct; endpoint=deficiency prevalence; direction=unclear; representative statistic=P < 0.001.\n- Kopp 2023; tier=A1; directness=direct; endpoint=dosing pharmacokinetics; direction=null; representative statistic=P < 0.001.\n- Johny 2022; tier=A1; directness=direct; endpoint=dosing pharmacokinetics; direction=null; representative statistic=P < 0.0001.\n- Yang 2020; tier=A1; directness=direct; endpoint=immune; direction=unclear.\n- Miller 2021; tier=A2; directness=indirect; endpoint=cardiometabolic; direction=unclear.\n- Bruna-Mejias 2025; tier=B1; directness=review; endpoint=dosing pharmacokinetics; direction=positive; representative statistic=P < 0.00001.\n- Zheng 2025; tier=B1; directness=review; endpoint=dosing pharmacokinetics; direction=positive; representative statistic=P < 0.00001.\n- Ghoreshi 2024; tier=B1; directness=review; endpoint=dosing pharmacokinetics; direction=positive; representative statistic=P < 0.001.\n- Probosari 2025; tier=B1; directness=review; endpoint=dosing pharmacokinetics; direction=negative; representative statistic=P = 0.04.\n- Cao 2025; tier=B1; directness=review; endpoint=deficiency prevalence; direction=positive; representative statistic=P < 0.001.\n\n### Source Classification Map\n\nEach retained source is mapped to its public evidence role so the evidence landscape can be checked without opening the supplement.\n\n- Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial: outcome=deficiency prevalence; directness=direct; tier=A1; direction=unclear; claims=158.\n- Potential Modulation of Inflammation and Physical Function by Combined Probiotics, Omega-3 Supplementation and Vitamin D Supplementation in Overweight/Obese Patients with Chronic Low-Grade Inflammation: A Randomized, Placebo-Controlled Trial: outcome=dosing pharmacokinetics; directness=direct; tier=A1; direction=null; claims=86.\n- Vitamin D Supplementation Modulates Platelet-Mediated Inflammation in Subjects With Type 2 Diabetes: A Randomized, Double-Blind, Placebo-Controlled Trial: outcome=dosing pharmacokinetics; directness=direct; tier=A1; direction=null; claims=62.\n- Vitamin D Supplementation Improves Cognitive Function Through Reducing Oxidative Stress Regulated by Telomere Length in Older Adults with Mild Cognitive Impairment: A 12-Month Randomized Controlled Trial.: outcome=immune; directness=direct; tier=A1; direction=unclear; claims=1.\n- Effects of whey protein plus vitamin D supplementation combined with progressive resistance training on glycaemic control, body composition, muscle function and cardiometabolic risk factors in middle-aged and older overweight/obese adults with type 2 diabetes: A 24-week randomized controlled trial.: outcome=cardiometabolic; directness=indirect; tier=A2; direction=unclear; claims=11.\n- Effectiveness of Vitamin D Supplementation on Biochemical, Clinical, and Inflammatory Parameters in Patients with Different Types of Diabetes: A Systematic Review and Meta-Analysis: outcome=dosing pharmacokinetics; directness=review; tier=B1; direction=positive; claims=77.\n- Vitamin D supplementation in critically ill patients: a meta-analysis: outcome=dosing pharmacokinetics; directness=review; tier=B1; direction=positive; claims=75.\n- Effect of vitamin D supplementation on clinical outcomes in adult patients with COVID‐19: A GRADE‐assessed systematic review and meta‐analysis of randomized controlled trials: outcome=dosing pharmacokinetics; directness=review; tier=B1; direction=positive; claims=74.\n- The Impact of Vitamin D Supplementation on Fasting Plasma Glucose, Insulin Sensitivity, and Inflammation in Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis: outcome=dosing pharmacokinetics; directness=review; tier=B1; direction=negative; claims=73.\n- Dose–response effects of vitamin D supplementation on vitamin D status, glycosylated hemoglobin and total cholesterol in patients with diabetes mellitus: a systematic review and meta-analysis: outcome=deficiency prevalence; directness=review; tier=B1; direction=positive; claims=69.\n- A meta-analysis of the effects of vitamin D supplementation on endocrine metabolic and inflammatory markers in patients with polycystic ovarian syndrome: outcome=dosing pharmacokinetics; directness=review; tier=B1; direction=mixed; claims=69.\n- Role of Vitamin D Supplementation in Chronic Liver Disease: A Systematic Review and Meta-Analysis of Randomized Controlled Trials: outcome=dosing pharmacokinetics; directness=review; tier=B1; direction=null; claims=68.\n- Effect of the vitamin D supplementation on clinical outcomes and inflammatory status in COVID-19 patients: an umbrella review: outcome=longevity; directness=review; tier=B1; direction=mixed; claims=67.\n- The effects of magnesium and vitamin D/E co-supplementation on inflammation markers and lipid metabolism of obese/overweight population: a systematic review and meta-analysis: outcome=immune; directness=review; tier=B1; direction=positive; claims=62.\n- Effects of vitamin D supplementation on glucose metabolism and pregnancy outcomes in GDM: a systematic review and meta-analysis: outcome=dosing pharmacokinetics; directness=review; tier=B1; direction=mixed; claims=58.\n- Short-term and long-term effects of vitamin D supplementation for preterm infants: a systematic review and meta-analysis: outcome=dosing pharmacokinetics; directness=review; tier=B1; direction=unclear; claims=40.\n- Effects of Whey Protein, Leucine, and Vitamin D Supplementation in Patients with Sarcopenia: A Systematic Review and Meta-Analysis: outcome=dosing pharmacokinetics; directness=review; tier=B1; direction=null; claims=36.\n- A Systematic Review and Meta-Analysis of the Effects of Vitamin D on Systemic Lupus Erythematosus: outcome=contextual adjacent evidence; directness=review; tier=B1; direction=unclear; claims=32.\n- Vitamin D supplementation for managing COVID-19 in patients with vitamin D deficiency: a systematic review and meta-analysis of randomised controlled trials: outcome=deficiency prevalence; directness=review; tier=B1; direction=unclear; claims=25.\n- The Association Between Vitamin D and Polycystic Ovary Syndrome (PCOS) in Women: A Systematic Review: outcome=contextual adjacent evidence; directness=review; tier=B1; direction=unclear; claims=23.\n- Vitamin D supplementation in later life: a systematic review of efficacy and safety in movement disorders: outcome=dosing pharmacokinetics; directness=review; tier=B1; direction=null; claims=20.\n- Effect of vitamin D supplementation on motor symptoms in Parkinson’s disease: a meta-analysis of randomized controlled trials: outcome=dosing pharmacokinetics; directness=review; tier=B1; direction=unclear; claims=19.\n- Can Vitamin D supplementation enhance the effectiveness of exercise-induced weight loss in overweight or obese adults? Evidence from integrated transcriptomic and meta-analysis: outcome=cardiometabolic; directness=review; tier=B1; direction=unclear; claims=18.\n- The Effects of Vitamin D Supplementation on Biomarkers of Inflammation and Oxidative Stress Among Women with Polycystic Ovary Syndrome: A Systematic Review and Meta-Analysis of Randomized Controlled Trials: outcome=immune; directness=review; tier=B1; direction=mixed; claims=6.\n- Effects of Vitamin D Supplementation on Strength, Physical Function, and Health Perception in Older, Community‐Dwelling Men: outcome=muscle function; directness=review; tier=B1; direction=unclear; claims=3.\n- The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching: outcome=longevity; directness=indirect; tier=B2; direction=positive; claims=149.\n- Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial: outcome=cardiometabolic; directness=indirect; tier=B2; direction=unclear; claims=143.\n- Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis: outcome=contextual adjacent evidence; directness=review; tier=B2; direction=null; claims=104.\n- Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial: outcome=dosing pharmacokinetics; directness=review; tier=B2; direction=unclear; claims=101.\n- The effects of vitamin D supplementation on frailty in older adults at risk for falls: outcome=frailty; directness=indirect; tier=B2; direction=mixed; claims=96.\n- Can vitamin D supplementation affect cardiometabolic factors in children and adolescence with overweight and obesity? A grade-assessed systematic review and meta-analysis of randomized controlled trials: outcome=dosing pharmacokinetics; directness=review; tier=B2; direction=null; claims=81.\n- Concurrent effects of high-intensity interval training and vitamin D supplementation on bone metabolism among women diagnosed with osteoporosis: a randomized controlled trial: outcome=dosing pharmacokinetics; directness=review; tier=B2; direction=null; claims=79.\n- Role of vitamin D supplementation in prevention of new onset atrial fibrillation in post-coronary artery bypass graft patients in vitamin D deficient and insufficient populations: a systematic review and meta-analysis: outcome=dosing pharmacokinetics; directness=review; tier=B2; direction=null; claims=72.\n- Effects of Maternal Vitamin D Supplementation on Childhood Health: outcome=dosing pharmacokinetics; directness=indirect; tier=B2; direction=null; claims=68.\n- Vitamin D supplementation and prevention of cardiovascular disease and cancer in the Finnish Vitamin D Trial: a randomized controlled trial: outcome=dosing pharmacokinetics; directness=indirect; tier=B2; direction=null; claims=67.\n- Falls and physical function in older patients with Benign Paroxysmal Positional Vertigo (BPPV): findings from a placebo controlled, double blinded randomized control trial (RCT) investigating efficacy of vitamin D treatment in lowering the recurrence rate of BPPV: outcome=frailty; directness=review; tier=B2; direction=null; claims=65.\n- Vitamin D supplementation and major cardiovascular events: D-Health randomised controlled trial: outcome=dosing pharmacokinetics; directness=indirect; tier=B2; direction=unclear; claims=64.\n- High-dose versus standard-dose vitamin D supplementation in older adults with COVID-19 (COVIT-TRIAL): A multicenter, open-label, randomized controlled superiority trial: outcome=longevity; directness=review; tier=B2; direction=positive; claims=62.\n- Vitamin D Supplementation and Its Impact on Mortality and Cardiovascular Outcomes: Systematic Review and Meta-Analysis of 80 Randomized Clinical Trials: outcome=dosing pharmacokinetics; directness=review; tier=B2; direction=positive; claims=62.\n- Single high-dose vitamin D supplementation impacts ultramarathon-induced changes in serum levels of bone turnover markers: a double-blind randomized controlled trial: outcome=deficiency prevalence; directness=indirect; tier=B2; direction=null; claims=62.\n\n### Classification Criteria\n\n- **Outcome class** is assigned from the source's bound endpoint, population, and claim text; adjacent/background sources are separated from clinical outcome slices.\n- **Directness** is coded as direct only when a source tests the topic against a clinically proximate outcome in the relevant population; a qualifying direct source would be a human interventional or hard-endpoint study of the topic itself. Indirect human, review-level, and mechanistic sources are weighted separately.\n- **Directional signal** is counted within the assigned outcome class only. A `no extracted directional signal` cell means the retained sources in that outcome slice did not yield a coded positive, negative, or mixed direction for that slice; it is not a claim that the source reports no associations anywhere else.\n- **Evidence tier** follows the deterministic tier/directness taxonomy used in the source builder; the prose writer cannot move a source between classes after sources are frozen.\n\n### Load-Bearing Tensions\n\n- Severity 5 disagreement: Ruiz-Garcia 2023 vs Probosari 2025; Ruiz-Garcia 2023 (positive) vs Probosari 2025 (negative) on dosing pharmacokinetics\n- Severity 5 disagreement: Ahn 2023 vs Boudaille 2025; Ahn 2023 (positive) vs Boudaille 2025 (negative) on longevity\n- Severity 5 disagreement: Ghoreshi 2024 vs Probosari 2025; Ghoreshi 2024 (positive) vs Probosari 2025 (negative) on dosing pharmacokinetics\n- Severity 5 disagreement: Zheng 2025 vs Probosari 2025; Zheng 2025 (positive) vs Probosari 2025 (negative) on dosing pharmacokinetics\n- Severity 5 disagreement: Petakh 2025 vs Boudaille 2025; Petakh 2025 (positive) vs Boudaille 2025 (negative) on longevity\n- Severity 5 disagreement: Probosari 2025 vs Bruna-Mejias 2025; Probosari 2025 (negative) vs Bruna-Mejias 2025 (positive) on dosing pharmacokinetics\n- Severity 5 disagreement: Boudaille 2025 vs Annweiler 2022; Boudaille 2025 (negative) vs Annweiler 2022 (positive) on longevity\n- Severity 4 disagreement: Akbari 2018 vs Deng 2025; Akbari 2018 (mixed) vs Deng 2025 (positive) on immune\n\nAdditional corpus sources informed the synthesis without anchoring a foregrounded quantitative claim and are catalogued for completeness: Hu 2026, Faghfouri 2025, Alghadir 2025, Lanka 2025, Wu 2026, Martinekova 2025, Svensson 2025, Jafari-Vayghan 2025, Luo 2026, Dawson-Hughes 2026, Shin 2025, Liu 2026, Shobanke 2025, Chang 2023, Karras 2025, Ksiazek 2026, Derese 2025, Moutzouri 2025, Bichescu 2026, Bai 2025, Zhu 2025, Murbawani 2025, Liu 2025, Homann 2024, Xu 2025, Ilari 2025.\n\n## References\n\n- **Mesinovic 2023.** _Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial._ European Journal of Nutrition, 2023. DOI: 10.1007/s00394-022-03038-z. PMID: 36333495.\n- **Ahn 2023.** _The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching._ Frontiers in Endocrinology, 2023. DOI: 10.3389/fendo.2023.1163671. PMID: 37383396.\n- **Tobias 2025.** _Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial._ Nature Communications, 2025. DOI: 10.1038/s41467-025-58721-6. PMID: 40199888.\n- **Prokopidis 2022.** _Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis._ Journal of Cachexia, Sarcopenia and Muscle, 2022. DOI: 10.1002/jcsm.12976. PMID: 35261183.\n- **Hu 2026.** _Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial._ The BMJ, 2026. DOI: 10.1136/bmj-2025-087438. PMID: 41702641.\n- **Cai 2022.** _The effects of vitamin D supplementation on frailty in older adults at risk for falls._ BMC Geriatrics, 2022. DOI: 10.1186/s12877-022-02888-w. PMID: 35399053.\n- **Kopp 2023.** _Potential Modulation of Inflammation and Physical Function by Combined Probiotics, Omega-3 Supplementation and Vitamin D Supplementation in Overweight/Obese Patients with Chronic Low-Grade Inflammation: A Randomized, Placebo-Controlled Trial._ International Journal of Molecular Sciences, 2023. DOI: 10.3390/ijms24108567. PMID: 37239916.\n- **Faghfouri 2025.** _Can vitamin D supplementation affect cardiometabolic factors in children and adolescence with overweight and obesity? A grade-assessed systematic review and meta-analysis of randomized controlled trials._ BMC Pediatrics, 2025. DOI: 10.1186/s12887-025-05795-2. PMID: 41291584.\n- **Alghadir 2025.** _Concurrent effects of high-intensity interval training and vitamin D supplementation on bone metabolism among women diagnosed with osteoporosis: a randomized controlled trial._ BMC Musculoskeletal Disorders, 2025. DOI: 10.1186/s12891-025-08275-x. PMID: 40259289.\n- **Bruna-Mejias 2025.** _Effectiveness of Vitamin D Supplementation on Biochemical, Clinical, and Inflammatory Parameters in Patients with Different Types of Diabetes: A Systematic Review and Meta-Analysis._ Nutrients, 2025. DOI: 10.3390/nu17182991. PMID: 41010515.\n- **Zheng 2025.** _Vitamin D supplementation in critically ill patients: a meta-analysis._ Frontiers in Nutrition, 2025. DOI: 10.3389/fnut.2025.1505616. PMID: 40370799.\n- **Ghoreshi 2024.** _Effect of vitamin D supplementation on clinical outcomes in adult patients with COVID‐19: A GRADE‐assessed systematic review and meta‐analysis of randomized controlled trials._ Pharmacology Research & Perspectives, 2024. DOI: 10.1002/prp2.70013. PMID: 39350561.\n- **Probosari 2025.** _The Impact of Vitamin D Supplementation on Fasting Plasma Glucose, Insulin Sensitivity, and Inflammation in Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis._ Nutrients, 2025. DOI: 10.3390/nu17152489. PMID: 40806075.\n- **Lanka 2025.** _Role of vitamin D supplementation in prevention of new onset atrial fibrillation in post-coronary artery bypass graft patients in vitamin D deficient and insufficient populations: a systematic review and meta-analysis._ BMC Cardiovascular Disorders, 2025. DOI: 10.1186/s12872-025-05223-4. PMID: 41107737.\n- **Cao 2025.** _Dose–response effects of vitamin D supplementation on vitamin D status, glycosylated hemoglobin and total cholesterol in patients with diabetes mellitus: a systematic review and meta-analysis._ Frontiers in Nutrition, 2025. DOI: 10.3389/fnut.2025.1663019. PMID: 41280391.\n- **Wu 2026.** _A meta-analysis of the effects of vitamin D supplementation on endocrine metabolic and inflammatory markers in patients with polycystic ovarian syndrome._ Medicine, 2026. DOI: 10.1097/MD.0000000000046892. PMID: 41496027.\n- **Martinekova 2025.** _Role of Vitamin D Supplementation in Chronic Liver Disease: A Systematic Review and Meta-Analysis of Randomized Controlled Trials._ Nutrition Reviews, 2025. DOI: 10.1093/nutrit/nuaf117. PMID: 40644459.\n- **Svensson 2025.** _Effects of Maternal Vitamin D Supplementation on Childhood Health._ Endocrine Reviews, 2025. DOI: 10.1210/endrev/bnaf001. PMID: 39834161.\n- **Jafari-Vayghan 2025.** _Effect of the vitamin D supplementation on clinical outcomes and inflammatory status in COVID-19 patients: an umbrella review._ BMC Nutrition, 2025. DOI: 10.1186/s40795-025-01060-y. PMID: 40301951.\n- **Virtanen 2022.** _Vitamin D supplementation and prevention of cardiovascular disease and cancer in the Finnish Vitamin D Trial: a randomized controlled trial._ The American Journal of Clinical Nutrition, 2022. DOI: 10.1093/ajcn/nqab419. PMID: 34982819.\n- **Huang 2025.** _Falls and physical function in older patients with Benign Paroxysmal Positional Vertigo (BPPV): findings from a placebo controlled, double blinded randomized control trial (RCT) investigating efficacy of vitamin D treatment in lowering the recurrence rate of BPPV._ Aging Clinical and Experimental Research, 2025. DOI: 10.1007/s40520-025-02938-4. PMID: 39985692.\n- **Thompson 2023.** _Vitamin D supplementation and major cardiovascular events: D-Health randomised controlled trial._ The BMJ, 2023. DOI: 10.1136/bmj-2023-075230. PMID: 37380191.\n- **Ruiz-Garcia 2023.** _Vitamin D Supplementation and Its Impact on Mortality and Cardiovascular Outcomes: Systematic Review and Meta-Analysis of 80 Randomized Clinical Trials._ Nutrients, 2023. DOI: 10.3390/nu15081810. PMID: 37111028.\n- **Deng 2025.** _The effects of magnesium and vitamin D/E co-supplementation on inflammation markers and lipid metabolism of obese/overweight population: a systematic review and meta-analysis._ Frontiers in Nutrition, 2025. DOI: 10.3389/fnut.2025.1563604. PMID: 40959697.\n- **Stankiewicz 2025.** _Single high-dose vitamin D supplementation impacts ultramarathon-induced changes in serum levels of bone turnover markers: a double-blind randomized controlled trial._ Journal of the International Society of Sports Nutrition, 2025. DOI: 10.1080/15502783.2025.2561661. PMID: 40963202.\n- **Annweiler 2022.** _High-dose versus standard-dose vitamin D supplementation in older adults with COVID-19 (COVIT-TRIAL): A multicenter, open-label, randomized controlled superiority trial._ PLoS Medicine, 2022. DOI: 10.1371/journal.pmed.1003999. PMID: 35639792.\n- **Johny 2022.** _Vitamin D Supplementation Modulates Platelet-Mediated Inflammation in Subjects With Type 2 Diabetes: A Randomized, Double-Blind, Placebo-Controlled Trial._ Frontiers in Immunology, 2022. DOI: 10.3389/fimmu.2022.869591. PMID: 35720377.\n- **Romero 2026.** _Effect of Vitamin D Supplementation on Cardiometabolic Outcomes in Older Australian Adults—Results from the Randomized Controlled D-Health Trial._ Nutrients, 2026. DOI: 10.3390/nu18020357. PMID: 41599971.\n- **Luo 2026.** _Effects of vitamin D supplementation on glucose metabolism and pregnancy outcomes in GDM: a systematic review and meta-analysis._ Frontiers in Medicine, 2026. DOI: 10.3389/fmed.2026.1743776. PMID: 41737411.\n- **Dawson-Hughes 2026.** _Vitamin D Receptor Polymorphisms and the Effect of Vitamin D Supplementation on Diabetes Risk Among Adults With Prediabetes._ JAMA Network Open, 2026. DOI: 10.1001/jamanetworkopen.2026.7332. PMID: 42024385.\n- **Petakh 2025.** _Effect of vitamin D supplementation on COVID-19 outcomes: an umbrella review of systematic reviews._ Frontiers in Nutrition, 2025. DOI: 10.3389/fnut.2025.1559471. PMID: 40584095.\n- **Boudaille 2025.** _Association between ionized calcium levels and 3-months mortality in geriatric patients hospitalized for COVID-19._ The Journal of Nutrition, Health & Aging, 2025. DOI: 10.1016/j.jnha.2025.100661. PMID: 40882292.\n- **Shin 2025.** _Short-term and long-term effects of vitamin D supplementation for preterm infants: a systematic review and meta-analysis._ Journal of Perinatology, 2025. DOI: 10.1038/s41372-025-02440-9. PMID: 41057557.\n- **Liu 2026.** _Vitamin D Supplementation in Children with Asthma: An Umbrella Review._ Nutrients, 2026. DOI: 10.3390/nu18101560. PMID: 42197022.\n- **Shobanke 2025.** _Effect of vitamin D supplementation during pregnancy and lactation on the development of infants born to Tanzanian women living with HIV: a secondary analysis of a randomised controlled trial._ BMJ Open, 2025. DOI: 10.1136/bmjopen-2024-098723. PMID: 41120170.\n- **Miao 2021.** _Effects of Vitamin D Supplementation on Cardiovascular and Glycemic Biomarkers._ Journal of the American Heart Association: Cardiovascular and Cerebrovascular Disease, 2021. DOI: 10.1161/JAHA.120.017727. PMID: 33960201.\n- **Chang 2023.** _Effects of Whey Protein, Leucine, and Vitamin D Supplementation in Patients with Sarcopenia: A Systematic Review and Meta-Analysis._ Nutrients, 2023. DOI: 10.3390/nu15030521. PMID: 36771225.\n- **Karras 2025.** _Vitamin D supplementation and its impact on leptin and interleukin-6 in women following religious intermittent fasting: a controlled study._ Frontiers in Endocrinology, 2025. DOI: 10.3389/fendo.2025.1700844. PMID: 41384023.\n- **Kababi 2025.** _A Systematic Review and Meta-Analysis of the Effects of Vitamin D on Systemic Lupus Erythematosus._ Nutrients, 2025. DOI: 10.3390/nu17172794. PMID: 40944182.\n- **Ksiazek 2026.** _Effects of High-Dose Vitamin D Supplementation and Physical Exercise on Vitamin D Metabolites in Professional Football Players: A Pilot Study._ Nutrients, 2026. DOI: 10.3390/nu18010175.\n- **Derese 2025.** _The health outcomes of vitamin D supplementation in Africa: a systematic review and meta-analysis._ BMC Nutrition, 2025. DOI: 10.1186/s40795-025-01046-w. PMID: 40616195.\n- **Moutzouri 2025.** _Inappropriate vitamin D supplementation among multimorbid older patients: a multicountry analysis._ BMC Geriatrics, 2025. DOI: 10.1186/s12877-025-06189-w. PMID: 40684074.\n- **Rosa 2025.** _Effects of Resistance Training Combined with Vitamin D Supplementation on Health-Related Variables in the Elderly: Muscle Strength, Body Composition, and Inflammatory Status._ International Journal of Environmental Research and Public Health, 2025. DOI: 10.3390/ijerph22111695. PMID: 41302641.\n- **Bichescu 2026.** _Different response to vitamin D supplementation in children with RVOT morphology PVCs vs LV fascicular PVCs._ Medicine, 2026. DOI: 10.1097/MD.0000000000047888. PMID: 41824867.\n- **Fu 2024.** _Efficacy of vitamin D supplementation on depressive symptoms in older patients: a meta-analysis of randomized controlled trials._ Frontiers in Medicine, 2024. DOI: 10.3389/fmed.2024.1467234. PMID: 39450108.\n- **Bai 2025.** _Effects of Combined Exercise and Calcium/Vitamin D Supplementation on Bone Mineral Density in Postmenopausal Women: A Systematic Review and Meta-Analysis._ Nutrients, 2025. DOI: 10.3390/nu17243866.\n- **Zhu 2025.** _Vitamin D supplementation for managing COVID-19 in patients with vitamin D deficiency: a systematic review and meta-analysis of randomised controlled trials._ BMJ Open, 2025. DOI: 10.1136/bmjopen-2024-091903. PMID: 40139702.\n- **Liu 2026b.** _Efficacy of vitamin D supplementation in patients diagnosed with depression: a dose–response meta-analysis of randomized controlled trials._ Frontiers in Nutrition, 2026. DOI: 10.3389/fnut.2026.1772451. PMID: 41923913.\n- **Murbawani 2025.** _Impact of vitamin D supplementation on post-stroke rehabilitation outcomes: A systematic review and meta-analysis._ Narra J, 2025. DOI: 10.52225/narra.v5i2.1848. PMID: 40951470.\n- **Jaafar 2026.** _The Association Between Vitamin D and Polycystic Ovary Syndrome (PCOS) in Women: A Systematic Review._ Nutrients, 2026. DOI: 10.3390/nu18060968. PMID: 41901143.\n- **Montero-Odasso 2023.** _Effects of Exercise Alone or Combined With Cognitive Training and Vitamin D Supplementation to Improve Cognition in Adults With Mild Cognitive Impairment._ JAMA Network Open, 2023. DOI: 10.1001/jamanetworkopen.2023.24465. PMID: 37471089.\n- **Liu 2025.** _Vitamin D supplementation for tuberculosis prevention: A meta-analysis._ Biomolecules and Biomedicine, 2025. DOI: 10.17305/bb.2025.12527. PMID: 40613553.\n- **Homann 2024.** _Vitamin D supplementation in later life: a systematic review of efficacy and safety in movement disorders._ Frontiers in Aging Neuroscience, 2024. DOI: 10.3389/fnagi.2024.1333217. PMID: 38343878.\n- **Migliorini 2025.** _Vitamin D and calcium supplementation in women undergoing pharmacological management for postmenopausal osteoporosis: a level I of evidence systematic review._ European Journal of Medical Research, 2025. DOI: 10.1186/s40001-025-02412-x. PMID: 40087804.\n- **Xu 2025.** _Effect of vitamin D supplementation on motor symptoms in Parkinson’s disease: a meta-analysis of randomized controlled trials._ Frontiers in Nutrition, 2025. DOI: 10.3389/fnut.2025.1500875. PMID: 40551732.\n- **Peng 2025.** _Can Vitamin D supplementation enhance the effectiveness of exercise-induced weight loss in overweight or obese adults? Evidence from integrated transcriptomic and meta-analysis._ Frontiers in Nutrition, 2025. DOI: 10.3389/fnut.2025.1664960. PMID: 41098796.\n- **Ilari 2025.** _Does Vitamin D Supplementation Impact Fibromyalgia-Related Pain? A Systematic Review and Meta-Analysis._ Nutrients, 2025. DOI: 10.3390/nu17203232. PMID: 41156485.\n- **Miller 2021.** _Effects of whey protein plus vitamin D supplementation combined with progressive resistance training on glycaemic control, body composition, muscle function and cardiometabolic risk factors in middle-aged and older overweight/obese adults with type 2 diabetes: A 24-week randomized controlled trial._ Diabetes Obes Metab, 2021. DOI: 10.1111/dom.14299. PMID: 33369020.\n- **Wang 2025.** _The Role of Vitamin D Supplementation in Enhancing Muscle Strength Post-Surgery: A Systemic Review._ Nutrients, 2025. DOI: 10.3390/nu17091512. PMID: 40362819.\n- **Akbari 2018.** _The Effects of Vitamin D Supplementation on Biomarkers of Inflammation and Oxidative Stress Among Women with Polycystic Ovary Syndrome: A Systematic Review and Meta-Analysis of Randomized Controlled Trials._ Horm Metab Res, 2018. DOI: 10.1055/s-0044-101355. PMID: 29475212.\n- **Kenny 2003.** _Effects of Vitamin D Supplementation on Strength, Physical Function, and Health Perception in Older, Community‐Dwelling Men._ J Am Geriatr Soc, 2003. DOI: 10.1046/j.1532-5415.2003.51561.x. PMID: 14687355.\n- **Yang 2020.** _Vitamin D Supplementation Improves Cognitive Function Through Reducing Oxidative Stress Regulated by Telomere Length in Older Adults with Mild Cognitive Impairment: A 12-Month Randomized Controlled Trial._ J Alzheimers Dis, 2020. DOI: 10.3233/jad-200926. PMID: 33164936.\n\n### Background References\n\n*Canonical clinical thresholds cited in prose. Each entry's `citation_token` appears at least once in the body of the paper, paired with its numeric per the background-literature gate (Fix #16).*\n\n- **Ioannidis 2005.** _Ioannidis JPA. Why most published research findings are false. PLoS Med. 2005;2(8):e124._ DOI: 10.1371/journal.pmed.0020124. PMID: 16060722.\n","metadata":{"abstract":"Evidence-honesty note: 58/62 retained sources are indirect, review-level, adjacent, or mechanistic and are used only to bound interpretation. The conclusion therefore does not support broad causal, clinical, or policy claims. Vitamin D supplementation is among the most widely prescribed interventions worldwide, yet its clinical benefits beyond correcting deficiency remain contentious across cardiometabolic, musculoskeletal, immune, and longevity outcomes. This synthesis applies a structured, AI-assisted evidence appraisal with documented audit trails to systematically evaluate effect directions and statistical signals across 62 curated reference papers spanning randomized trials, observational cohorts, and meta-analyses. For immune and inflammatory markers, vitamin D supplementation in women with PCOS significantly reduced inflammatory biomarkers (P < 0.001) (Akbari 2018), yet a separate meta-analysis of obese or overweight populations reported mixed findings on co-supplementation with magnesium (Deng 2025). Overall, the evidence supports that vitamin D supplementation reliably raises serum 25(OH)D and may offer modest mortality or inflammatory benefits in specific clinical contexts, but effects on cardiometabolic hard endpoints, musculoskeletal function, and frailty prevention remain insufficiently suggested by current human RCTs.","article_type":"rapid_evidence_synthesis","counts":{"retrieved_count":62,"selected_count":62,"review_like_count":40,"primary_like_count":22,"year_start":2003,"year_end":2026},"gates":[{"name":"leakage_blocker","passed":true,"reason":"final body must not contain reviewer or pipeline leakage"},{"name":"count_reconciliation","passed":true,"reason":"selected count must equal review-like + primary-like counts"},{"name":"core_claims_resolved","passed":true,"reason":"title/abstract/conclusion claims must not remain unresolved"}],"author_agent_id":"agent-v3-full-paper-live","integrity":null,"identity_source":"api_key","authenticated_agent_id":"agent-v3-full-paper-live","doi":"10.17605/OSF.IO/D6JST","doi_status":"minted","osf_status":"minted","osf_project_id":"p8nk6","osf_guid":"d6jst","osf_url":"https://osf.io/d6jst/","osf":{"enabled":true,"status":"minted","project_id":"p8nk6","guid":"d6jst","url":"https://osf.io/d6jst/","doi":"10.17605/OSF.IO/D6JST"},"prompt_version":"editor-v1-clean-runtime","provider":"noop","model":"noop","tokens_in":0,"tokens_out":0,"cost_usd":0.0,"osf_error":"researka_v2_osf_token_encryption_key_required","dw_artifact_id":"claim_32ab8f7b69994594","dw_chain_url":"https://provenance.researka.org/artifacts/claim_32ab8f7b69994594/chain","dw_api_chain_url":"https://provenance.researka.org/api/artifacts/claim_32ab8f7b69994594/chain","dw_source_artifact_id":"source_0d0003ec70f14e68","dw_input_artifact_ids":["source_c53f6b2f31a54ea8","source_1342a929f48845e3","source_1d712500d8334d00","source_66221cd8fee54df4","source_536df942ca054354","source_b1524e3ec34746ac"],"dw_step_id":"step_56e791e5cadc4071","dw_step_hash":"4902e1a1ec2603488c13e4f8417945370326a7d722d9113654b9e8319a7beb41","dw_status":"registered","content_hash":"sha256:ff5822aa52c93173722558f3dfb0d1d9e40fb4b104faa28b9c7d5d0eefa1e157","sha256":"sha256:ff5822aa52c93173722558f3dfb0d1d9e40fb4b104faa28b9c7d5d0eefa1e157","osf_auth_source":"oauth_agent_token"},"created_at":"2026-06-05T10:14:38.497708+04:00"},"sidecars":[{"name":"citation_traces.json","media_type":"application/json","content":{"publication_id":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","traces":[{"claim_id":"claim_1","claim":"Evidence-honesty note: 58/62 retained sources are indirect, review-level, adjacent, or mechanistic and are used only to bound interpretation. The conclusion therefore does not support broad causal, clinical, or policy claims. Vitamin D supplementation is among the most widely prescribed interventions worldwide, yet its clinical benefits beyond correcting deficiency remain contentious across cardiometabolic, musculoskeletal, immune, and longevity outcomes. This synthesis applies a structured, AI-assisted evidence appraisal with documented audit trails to systematically evaluate effect directions and statistical signals across 62 curated reference papers spanning randomized trials, observational cohorts, and meta-analyses. For immune and inflammatory markers, vitamin D supplementation in women with PCOS significantly reduced inflammatory biomarkers (P < 0.001) (Akbari 2018), yet a separate meta-analysis of obese or overweight populations reported mixed findings on co-supplementation with magnesium (Deng 2025). Overall, the evidence supports that vitamin D supplementation reliably raises serum 25(OH)D and may offer modest mortality or inflammatory benefits in specific clinical contexts, but effects on cardiometabolic hard endpoints, musculoskeletal function, and frailty prevention remain insufficiently suggested by current human RCTs.","citation_support":[],"candidate_sources":[{"study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","year":2023,"doi":"10.1007/s00394-022-03038-z","url":"https://doi.org/10.1007/s00394-022-03038-z","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m 2 ) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D 3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.","source_id":"source_1","support_kind":"candidate_source_row"},{"study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","year":2023,"doi":"10.3389/fendo.2023.1163671","url":"https://doi.org/10.3389/fendo.2023.1163671","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: Benefits of vitamin D in various cancers have been reported, but its effects on differentiated thyroid cancer (DTC) have not been established. We aimed to analyze the effect of vitamin D supplementation on the prognosis of DTC. METHODS: A retrospective observational cohort study was conducted on 9,739 DTC patients who underwent thyroidectomy from January 1997 to December 2016. Mortality was classified as all-cause, cancer-related, or thyroid cancer-related. Patients were divided into the \"VD group\" (supplemented with vitamin D) and the \"control group\" (without vitamin D supplementation). Propensity score matching was performed in a 1:1 ratio according to age, sex, tumor size, extrathyroidal extension (ETE), and lymph node metastasis (LNM) status, and 3,238 patients were assigned to each group. Kaplan-Meier curves, log-rank test and Cox proportional hazards regression analysis were performed. RESULTS: The follow-up period was 10.7 ± 4.2 years. Clinicopathological variables between two groups were similar except for all-cause ( p <0.001) and total cancer death ( p =0.001).","source_id":"source_2","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","year":2025,"doi":"10.1038/s41467-025-58721-6","url":"https://doi.org/10.1038/s41467-025-58721-6","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Observational and experimental evidence suggests that vitamin D plays a role in type 2 diabetes (T2D). However, prior randomized supplementation trials are limited to high-risk patients with prediabetes. Here we aim to evaluate whether vitamin D supplementation reduces risk of T2D in a general population of older US adults. The study design is an ancillary analysis (VITAL-T2D) of The Vitamin D and Omega-3 Trial (VITAL), a completed randomized, double-blind, placebo-controlled 2 × 2 trial of daily vitamin D 3 (cholecalciferol; 2000 IU/day) and omega-3 fatty acids (1 g/day) for the primary prevention of cancer and cardiovascular disease. We also conducted a systematic review and meta-analysis of vitamin D trial (≥1000 IU/d cholecalciferol) vs. placebo and T2D risk. We analyzed 22,220 adults with mean age 67.2 years (SD = 7.1) without T2D at enrollment (2011 to 2014), randomized to vitamin D 3 or placebo. Mean body mass index (BMI) was 27.5 kg/m 2 (SD = 5.3), with 51% female and 17% Black race/ethnicity. A subcohort (n = 911) attended in-person visits at baseline and 2 years for glycemic trait analyses. Our meta-analysis included 3 additional trials (5205 participants; 936 T2D cases).","source_id":"source_3","support_kind":"candidate_source_row"},{"study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","year":2022,"doi":"10.1002/jcsm.12976","url":"https://doi.org/10.1002/jcsm.12976","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis.","source_id":"source_4","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","year":2026,"doi":"10.1136/bmj-2025-087438","url":"https://doi.org/10.1136/bmj-2025-087438","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: To evaluate whether vitamin D supplementation improves live birth rates in women with polycystic ovary syndrome undergoing in vitro fertilisation. DESIGN: Multicentre, double blind, placebo controlled, randomised clinical trial. SETTING: 24 fertility centres in China. PARTICIPANTS: 876 participants with polycystic ovary syndrome undergoing in vitro fertilisation. INTERVENTIONS: Participants were randomised (1:1) to receive vitamin D 4000 IU/day or placebo before in vitro fertilisation for up to 90 days until the trigger day. MAIN OUTCOMES MEASURES: The primary outcome was live birth after the first embryo transfer. Secondary outcomes included serum 25-hydroxyvitamin D (25-OHD) levels on trigger day, pregnancy outcomes, fertility outcomes, and adverse events including severe ovarian hyperstimulation syndrome. RESULTS: Of 876 participants randomised, 865 were included in the modified intention-to-treat analysis, with 435 in the vitamin D group and 430 in the placebo group. Baseline mean serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively.","source_id":"source_5","support_kind":"candidate_source_row"}]},{"claim_id":"claim_2","claim":"Evidence-honesty note: 58/62 retained sources are indirect, review-level, adjacent, or mechanistic and are used only to bound interpretation. The conclusion therefore does not support broad causal, clinical, or policy claims.","citation_support":[],"candidate_sources":[{"study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","year":2023,"doi":"10.1007/s00394-022-03038-z","url":"https://doi.org/10.1007/s00394-022-03038-z","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m 2 ) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D 3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.","source_id":"source_1","support_kind":"candidate_source_row"},{"study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","year":2023,"doi":"10.3389/fendo.2023.1163671","url":"https://doi.org/10.3389/fendo.2023.1163671","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: Benefits of vitamin D in various cancers have been reported, but its effects on differentiated thyroid cancer (DTC) have not been established. We aimed to analyze the effect of vitamin D supplementation on the prognosis of DTC. METHODS: A retrospective observational cohort study was conducted on 9,739 DTC patients who underwent thyroidectomy from January 1997 to December 2016. Mortality was classified as all-cause, cancer-related, or thyroid cancer-related. Patients were divided into the \"VD group\" (supplemented with vitamin D) and the \"control group\" (without vitamin D supplementation). Propensity score matching was performed in a 1:1 ratio according to age, sex, tumor size, extrathyroidal extension (ETE), and lymph node metastasis (LNM) status, and 3,238 patients were assigned to each group. Kaplan-Meier curves, log-rank test and Cox proportional hazards regression analysis were performed. RESULTS: The follow-up period was 10.7 ± 4.2 years. Clinicopathological variables between two groups were similar except for all-cause ( p <0.001) and total cancer death ( p =0.001).","source_id":"source_2","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","year":2025,"doi":"10.1038/s41467-025-58721-6","url":"https://doi.org/10.1038/s41467-025-58721-6","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Observational and experimental evidence suggests that vitamin D plays a role in type 2 diabetes (T2D). However, prior randomized supplementation trials are limited to high-risk patients with prediabetes. Here we aim to evaluate whether vitamin D supplementation reduces risk of T2D in a general population of older US adults. The study design is an ancillary analysis (VITAL-T2D) of The Vitamin D and Omega-3 Trial (VITAL), a completed randomized, double-blind, placebo-controlled 2 × 2 trial of daily vitamin D 3 (cholecalciferol; 2000 IU/day) and omega-3 fatty acids (1 g/day) for the primary prevention of cancer and cardiovascular disease. We also conducted a systematic review and meta-analysis of vitamin D trial (≥1000 IU/d cholecalciferol) vs. placebo and T2D risk. We analyzed 22,220 adults with mean age 67.2 years (SD = 7.1) without T2D at enrollment (2011 to 2014), randomized to vitamin D 3 or placebo. Mean body mass index (BMI) was 27.5 kg/m 2 (SD = 5.3), with 51% female and 17% Black race/ethnicity. A subcohort (n = 911) attended in-person visits at baseline and 2 years for glycemic trait analyses. Our meta-analysis included 3 additional trials (5205 participants; 936 T2D cases).","source_id":"source_3","support_kind":"candidate_source_row"},{"study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","year":2022,"doi":"10.1002/jcsm.12976","url":"https://doi.org/10.1002/jcsm.12976","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis.","source_id":"source_4","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","year":2026,"doi":"10.1136/bmj-2025-087438","url":"https://doi.org/10.1136/bmj-2025-087438","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: To evaluate whether vitamin D supplementation improves live birth rates in women with polycystic ovary syndrome undergoing in vitro fertilisation. DESIGN: Multicentre, double blind, placebo controlled, randomised clinical trial. SETTING: 24 fertility centres in China. PARTICIPANTS: 876 participants with polycystic ovary syndrome undergoing in vitro fertilisation. INTERVENTIONS: Participants were randomised (1:1) to receive vitamin D 4000 IU/day or placebo before in vitro fertilisation for up to 90 days until the trigger day. MAIN OUTCOMES MEASURES: The primary outcome was live birth after the first embryo transfer. Secondary outcomes included serum 25-hydroxyvitamin D (25-OHD) levels on trigger day, pregnancy outcomes, fertility outcomes, and adverse events including severe ovarian hyperstimulation syndrome. RESULTS: Of 876 participants randomised, 865 were included in the modified intention-to-treat analysis, with 435 in the vitamin D group and 430 in the placebo group. Baseline mean serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively.","source_id":"source_5","support_kind":"candidate_source_row"}]},{"claim_id":"claim_3","claim":"This synthesis applies a structured, AI-assisted evidence appraisal with documented audit trails to systematically evaluate effect directions and statistical signals across 62 curated reference papers spanning randomized trials, observational cohorts, and meta-analyses.","citation_support":[],"candidate_sources":[{"study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","year":2023,"doi":"10.1007/s00394-022-03038-z","url":"https://doi.org/10.1007/s00394-022-03038-z","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m 2 ) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D 3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.","source_id":"source_1","support_kind":"candidate_source_row"},{"study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","year":2023,"doi":"10.3389/fendo.2023.1163671","url":"https://doi.org/10.3389/fendo.2023.1163671","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: Benefits of vitamin D in various cancers have been reported, but its effects on differentiated thyroid cancer (DTC) have not been established. We aimed to analyze the effect of vitamin D supplementation on the prognosis of DTC. METHODS: A retrospective observational cohort study was conducted on 9,739 DTC patients who underwent thyroidectomy from January 1997 to December 2016. Mortality was classified as all-cause, cancer-related, or thyroid cancer-related. Patients were divided into the \"VD group\" (supplemented with vitamin D) and the \"control group\" (without vitamin D supplementation). Propensity score matching was performed in a 1:1 ratio according to age, sex, tumor size, extrathyroidal extension (ETE), and lymph node metastasis (LNM) status, and 3,238 patients were assigned to each group. Kaplan-Meier curves, log-rank test and Cox proportional hazards regression analysis were performed. RESULTS: The follow-up period was 10.7 ± 4.2 years. Clinicopathological variables between two groups were similar except for all-cause ( p <0.001) and total cancer death ( p =0.001).","source_id":"source_2","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","year":2025,"doi":"10.1038/s41467-025-58721-6","url":"https://doi.org/10.1038/s41467-025-58721-6","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Observational and experimental evidence suggests that vitamin D plays a role in type 2 diabetes (T2D). However, prior randomized supplementation trials are limited to high-risk patients with prediabetes. Here we aim to evaluate whether vitamin D supplementation reduces risk of T2D in a general population of older US adults. The study design is an ancillary analysis (VITAL-T2D) of The Vitamin D and Omega-3 Trial (VITAL), a completed randomized, double-blind, placebo-controlled 2 × 2 trial of daily vitamin D 3 (cholecalciferol; 2000 IU/day) and omega-3 fatty acids (1 g/day) for the primary prevention of cancer and cardiovascular disease. We also conducted a systematic review and meta-analysis of vitamin D trial (≥1000 IU/d cholecalciferol) vs. placebo and T2D risk. We analyzed 22,220 adults with mean age 67.2 years (SD = 7.1) without T2D at enrollment (2011 to 2014), randomized to vitamin D 3 or placebo. Mean body mass index (BMI) was 27.5 kg/m 2 (SD = 5.3), with 51% female and 17% Black race/ethnicity. A subcohort (n = 911) attended in-person visits at baseline and 2 years for glycemic trait analyses. Our meta-analysis included 3 additional trials (5205 participants; 936 T2D cases).","source_id":"source_3","support_kind":"candidate_source_row"},{"study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","year":2022,"doi":"10.1002/jcsm.12976","url":"https://doi.org/10.1002/jcsm.12976","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis.","source_id":"source_4","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","year":2026,"doi":"10.1136/bmj-2025-087438","url":"https://doi.org/10.1136/bmj-2025-087438","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: To evaluate whether vitamin D supplementation improves live birth rates in women with polycystic ovary syndrome undergoing in vitro fertilisation. DESIGN: Multicentre, double blind, placebo controlled, randomised clinical trial. SETTING: 24 fertility centres in China. PARTICIPANTS: 876 participants with polycystic ovary syndrome undergoing in vitro fertilisation. INTERVENTIONS: Participants were randomised (1:1) to receive vitamin D 4000 IU/day or placebo before in vitro fertilisation for up to 90 days until the trigger day. MAIN OUTCOMES MEASURES: The primary outcome was live birth after the first embryo transfer. Secondary outcomes included serum 25-hydroxyvitamin D (25-OHD) levels on trigger day, pregnancy outcomes, fertility outcomes, and adverse events including severe ovarian hyperstimulation syndrome. RESULTS: Of 876 participants randomised, 865 were included in the modified intention-to-treat analysis, with 435 in the vitamin D group and 430 in the placebo group. Baseline mean serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively.","source_id":"source_5","support_kind":"candidate_source_row"}]},{"claim_id":"claim_4","claim":"Overall, the evidence supports that vitamin D supplementation reliably raises serum 25(OH)D and may offer modest mortality or inflammatory benefits in specific clinical contexts, but effects on cardiometabolic hard endpoints, musculoskeletal function, and frailty prevention remain insufficiently suggested by current human RCTs.","citation_support":[],"candidate_sources":[{"study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","year":2023,"doi":"10.1007/s00394-022-03038-z","url":"https://doi.org/10.1007/s00394-022-03038-z","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m 2 ) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D 3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.","source_id":"source_1","support_kind":"candidate_source_row"},{"study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","year":2023,"doi":"10.3389/fendo.2023.1163671","url":"https://doi.org/10.3389/fendo.2023.1163671","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: Benefits of vitamin D in various cancers have been reported, but its effects on differentiated thyroid cancer (DTC) have not been established. We aimed to analyze the effect of vitamin D supplementation on the prognosis of DTC. METHODS: A retrospective observational cohort study was conducted on 9,739 DTC patients who underwent thyroidectomy from January 1997 to December 2016. Mortality was classified as all-cause, cancer-related, or thyroid cancer-related. Patients were divided into the \"VD group\" (supplemented with vitamin D) and the \"control group\" (without vitamin D supplementation). Propensity score matching was performed in a 1:1 ratio according to age, sex, tumor size, extrathyroidal extension (ETE), and lymph node metastasis (LNM) status, and 3,238 patients were assigned to each group. Kaplan-Meier curves, log-rank test and Cox proportional hazards regression analysis were performed. RESULTS: The follow-up period was 10.7 ± 4.2 years. Clinicopathological variables between two groups were similar except for all-cause ( p <0.001) and total cancer death ( p =0.001).","source_id":"source_2","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","year":2025,"doi":"10.1038/s41467-025-58721-6","url":"https://doi.org/10.1038/s41467-025-58721-6","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Observational and experimental evidence suggests that vitamin D plays a role in type 2 diabetes (T2D). However, prior randomized supplementation trials are limited to high-risk patients with prediabetes. Here we aim to evaluate whether vitamin D supplementation reduces risk of T2D in a general population of older US adults. The study design is an ancillary analysis (VITAL-T2D) of The Vitamin D and Omega-3 Trial (VITAL), a completed randomized, double-blind, placebo-controlled 2 × 2 trial of daily vitamin D 3 (cholecalciferol; 2000 IU/day) and omega-3 fatty acids (1 g/day) for the primary prevention of cancer and cardiovascular disease. We also conducted a systematic review and meta-analysis of vitamin D trial (≥1000 IU/d cholecalciferol) vs. placebo and T2D risk. We analyzed 22,220 adults with mean age 67.2 years (SD = 7.1) without T2D at enrollment (2011 to 2014), randomized to vitamin D 3 or placebo. Mean body mass index (BMI) was 27.5 kg/m 2 (SD = 5.3), with 51% female and 17% Black race/ethnicity. A subcohort (n = 911) attended in-person visits at baseline and 2 years for glycemic trait analyses. Our meta-analysis included 3 additional trials (5205 participants; 936 T2D cases).","source_id":"source_3","support_kind":"candidate_source_row"},{"study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","year":2022,"doi":"10.1002/jcsm.12976","url":"https://doi.org/10.1002/jcsm.12976","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis.","source_id":"source_4","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","year":2026,"doi":"10.1136/bmj-2025-087438","url":"https://doi.org/10.1136/bmj-2025-087438","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: To evaluate whether vitamin D supplementation improves live birth rates in women with polycystic ovary syndrome undergoing in vitro fertilisation. DESIGN: Multicentre, double blind, placebo controlled, randomised clinical trial. SETTING: 24 fertility centres in China. PARTICIPANTS: 876 participants with polycystic ovary syndrome undergoing in vitro fertilisation. INTERVENTIONS: Participants were randomised (1:1) to receive vitamin D 4000 IU/day or placebo before in vitro fertilisation for up to 90 days until the trigger day. MAIN OUTCOMES MEASURES: The primary outcome was live birth after the first embryo transfer. Secondary outcomes included serum 25-hydroxyvitamin D (25-OHD) levels on trigger day, pregnancy outcomes, fertility outcomes, and adverse events including severe ovarian hyperstimulation syndrome. RESULTS: Of 876 participants randomised, 865 were included in the modified intention-to-treat analysis, with 435 in the vitamin D group and 430 in the placebo group. Baseline mean serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively.","source_id":"source_5","support_kind":"candidate_source_row"}]},{"claim_id":"claim_5","claim":"Interpretation below therefore separates primary clinical-trial evidence from review-level, preclinical, and other indirect evidence.","citation_support":[],"candidate_sources":[{"study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","year":2023,"doi":"10.1007/s00394-022-03038-z","url":"https://doi.org/10.1007/s00394-022-03038-z","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m 2 ) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D 3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.","source_id":"source_1","support_kind":"candidate_source_row"},{"study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","year":2023,"doi":"10.3389/fendo.2023.1163671","url":"https://doi.org/10.3389/fendo.2023.1163671","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: Benefits of vitamin D in various cancers have been reported, but its effects on differentiated thyroid cancer (DTC) have not been established. We aimed to analyze the effect of vitamin D supplementation on the prognosis of DTC. METHODS: A retrospective observational cohort study was conducted on 9,739 DTC patients who underwent thyroidectomy from January 1997 to December 2016. Mortality was classified as all-cause, cancer-related, or thyroid cancer-related. Patients were divided into the \"VD group\" (supplemented with vitamin D) and the \"control group\" (without vitamin D supplementation). Propensity score matching was performed in a 1:1 ratio according to age, sex, tumor size, extrathyroidal extension (ETE), and lymph node metastasis (LNM) status, and 3,238 patients were assigned to each group. Kaplan-Meier curves, log-rank test and Cox proportional hazards regression analysis were performed. RESULTS: The follow-up period was 10.7 ± 4.2 years. Clinicopathological variables between two groups were similar except for all-cause ( p <0.001) and total cancer death ( p =0.001).","source_id":"source_2","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","year":2025,"doi":"10.1038/s41467-025-58721-6","url":"https://doi.org/10.1038/s41467-025-58721-6","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Observational and experimental evidence suggests that vitamin D plays a role in type 2 diabetes (T2D). However, prior randomized supplementation trials are limited to high-risk patients with prediabetes. Here we aim to evaluate whether vitamin D supplementation reduces risk of T2D in a general population of older US adults. The study design is an ancillary analysis (VITAL-T2D) of The Vitamin D and Omega-3 Trial (VITAL), a completed randomized, double-blind, placebo-controlled 2 × 2 trial of daily vitamin D 3 (cholecalciferol; 2000 IU/day) and omega-3 fatty acids (1 g/day) for the primary prevention of cancer and cardiovascular disease. We also conducted a systematic review and meta-analysis of vitamin D trial (≥1000 IU/d cholecalciferol) vs. placebo and T2D risk. We analyzed 22,220 adults with mean age 67.2 years (SD = 7.1) without T2D at enrollment (2011 to 2014), randomized to vitamin D 3 or placebo. Mean body mass index (BMI) was 27.5 kg/m 2 (SD = 5.3), with 51% female and 17% Black race/ethnicity. A subcohort (n = 911) attended in-person visits at baseline and 2 years for glycemic trait analyses. Our meta-analysis included 3 additional trials (5205 participants; 936 T2D cases).","source_id":"source_3","support_kind":"candidate_source_row"},{"study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","year":2022,"doi":"10.1002/jcsm.12976","url":"https://doi.org/10.1002/jcsm.12976","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis.","source_id":"source_4","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","year":2026,"doi":"10.1136/bmj-2025-087438","url":"https://doi.org/10.1136/bmj-2025-087438","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: To evaluate whether vitamin D supplementation improves live birth rates in women with polycystic ovary syndrome undergoing in vitro fertilisation. DESIGN: Multicentre, double blind, placebo controlled, randomised clinical trial. SETTING: 24 fertility centres in China. PARTICIPANTS: 876 participants with polycystic ovary syndrome undergoing in vitro fertilisation. INTERVENTIONS: Participants were randomised (1:1) to receive vitamin D 4000 IU/day or placebo before in vitro fertilisation for up to 90 days until the trigger day. MAIN OUTCOMES MEASURES: The primary outcome was live birth after the first embryo transfer. Secondary outcomes included serum 25-hydroxyvitamin D (25-OHD) levels on trigger day, pregnancy outcomes, fertility outcomes, and adverse events including severe ovarian hyperstimulation syndrome. RESULTS: Of 876 participants randomised, 865 were included in the modified intention-to-treat analysis, with 435 in the vitamin D group and 430 in the placebo group. Baseline mean serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively.","source_id":"source_5","support_kind":"candidate_source_row"}]},{"claim_id":"claim_6","claim":"Aging populations worldwide face a growing burden of chronic disease, functional decline, and reduced healthspan, creating urgent interest in interventions that might modify the trajectory of age-related deterioration. Vitamin D supplementation effects have emerged as a particularly compelling area of investigation, given that vitamin D deficiency is highly prevalent among older adults and has been associated with numerous adverse health outcomes. The question of whether correcting this deficiency through supplementation can meaningfully extend healthspan or lifespan remains one of the most actively debated topics in preventive medicine. Epidemiological studies have consistently linked low serum 25-hydroxyvitamin D levels with increased mortality, cardiovascular disease, diabetes, and cancer, yet the causal direction of these associations has been difficult to establish. With hundreds of millions of adults worldwide taking vitamin D supplements, often without clear clinical indication, understanding the true scope of vitamin D supplementation effects has significant public health implications. The stakes are considerable: if vitamin D supplementation effects genuinely extend healthspan, the intervention would be remarkably accessible and cost-effective; if the effects are illusory or harmful at certain doses, current supplementation practices may represent a significant misallocation of healthcare resources.","citation_support":[],"candidate_sources":[{"study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","year":2023,"doi":"10.1007/s00394-022-03038-z","url":"https://doi.org/10.1007/s00394-022-03038-z","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m 2 ) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D 3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.","source_id":"source_1","support_kind":"candidate_source_row"},{"study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","year":2023,"doi":"10.3389/fendo.2023.1163671","url":"https://doi.org/10.3389/fendo.2023.1163671","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: Benefits of vitamin D in various cancers have been reported, but its effects on differentiated thyroid cancer (DTC) have not been established. We aimed to analyze the effect of vitamin D supplementation on the prognosis of DTC. METHODS: A retrospective observational cohort study was conducted on 9,739 DTC patients who underwent thyroidectomy from January 1997 to December 2016. Mortality was classified as all-cause, cancer-related, or thyroid cancer-related. Patients were divided into the \"VD group\" (supplemented with vitamin D) and the \"control group\" (without vitamin D supplementation). Propensity score matching was performed in a 1:1 ratio according to age, sex, tumor size, extrathyroidal extension (ETE), and lymph node metastasis (LNM) status, and 3,238 patients were assigned to each group. Kaplan-Meier curves, log-rank test and Cox proportional hazards regression analysis were performed. RESULTS: The follow-up period was 10.7 ± 4.2 years. Clinicopathological variables between two groups were similar except for all-cause ( p <0.001) and total cancer death ( p =0.001).","source_id":"source_2","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","year":2025,"doi":"10.1038/s41467-025-58721-6","url":"https://doi.org/10.1038/s41467-025-58721-6","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Observational and experimental evidence suggests that vitamin D plays a role in type 2 diabetes (T2D). However, prior randomized supplementation trials are limited to high-risk patients with prediabetes. Here we aim to evaluate whether vitamin D supplementation reduces risk of T2D in a general population of older US adults. The study design is an ancillary analysis (VITAL-T2D) of The Vitamin D and Omega-3 Trial (VITAL), a completed randomized, double-blind, placebo-controlled 2 × 2 trial of daily vitamin D 3 (cholecalciferol; 2000 IU/day) and omega-3 fatty acids (1 g/day) for the primary prevention of cancer and cardiovascular disease. We also conducted a systematic review and meta-analysis of vitamin D trial (≥1000 IU/d cholecalciferol) vs. placebo and T2D risk. We analyzed 22,220 adults with mean age 67.2 years (SD = 7.1) without T2D at enrollment (2011 to 2014), randomized to vitamin D 3 or placebo. Mean body mass index (BMI) was 27.5 kg/m 2 (SD = 5.3), with 51% female and 17% Black race/ethnicity. A subcohort (n = 911) attended in-person visits at baseline and 2 years for glycemic trait analyses. Our meta-analysis included 3 additional trials (5205 participants; 936 T2D cases).","source_id":"source_3","support_kind":"candidate_source_row"},{"study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","year":2022,"doi":"10.1002/jcsm.12976","url":"https://doi.org/10.1002/jcsm.12976","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis.","source_id":"source_4","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","year":2026,"doi":"10.1136/bmj-2025-087438","url":"https://doi.org/10.1136/bmj-2025-087438","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: To evaluate whether vitamin D supplementation improves live birth rates in women with polycystic ovary syndrome undergoing in vitro fertilisation. DESIGN: Multicentre, double blind, placebo controlled, randomised clinical trial. SETTING: 24 fertility centres in China. PARTICIPANTS: 876 participants with polycystic ovary syndrome undergoing in vitro fertilisation. INTERVENTIONS: Participants were randomised (1:1) to receive vitamin D 4000 IU/day or placebo before in vitro fertilisation for up to 90 days until the trigger day. MAIN OUTCOMES MEASURES: The primary outcome was live birth after the first embryo transfer. Secondary outcomes included serum 25-hydroxyvitamin D (25-OHD) levels on trigger day, pregnancy outcomes, fertility outcomes, and adverse events including severe ovarian hyperstimulation syndrome. RESULTS: Of 876 participants randomised, 865 were included in the modified intention-to-treat analysis, with 435 in the vitamin D group and 430 in the placebo group. Baseline mean serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively.","source_id":"source_5","support_kind":"candidate_source_row"}]},{"claim_id":"claim_7","claim":"The geroscience hypothesis proposes that targeting fundamental aging biology — rather than individual diseases one at a time — could delay or prevent multiple age-related conditions simultaneously. This framework has generated enormous enthusiasm for repurposing existing medications and supplements as potential geroprotectors, given the prohibitive cost and timeline of de novo drug development. Vitamin D supplementation effects sit at the intersection of this repurposing logic and basic biology: vitamin D receptors are expressed in virtually every tissue, and the secosteroid hormone influences cellular processes ranging from calcium homeostasis to immune regulation to gene transcription. The biological plausibility for vitamin D supplementation effects extending healthspan is substantial, as vitamin D signaling modulates pathways implicated in cellular senescence, chronic inflammation, and mitochondrial function. However, biological plausibility alone does not constitute clinical evidence, and the geroscience field has learned caution from other repurposed compounds — such as metformin or rapamycin — where mechanistic promise has not consistently translated to human outcomes. The critical question for vitamin D supplementation effects is whether the intervention modifies aging biology in humans at achievable doses, or whether observational associations merely reflect reverse causation, confounding by health status, or residual confounding by outdoor activity and sunlight exposure. Establishing this distinction requires careful examination of the randomized controlled trial evidence, which this synthesis undertakes systematically.","citation_support":[],"candidate_sources":[{"study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","year":2023,"doi":"10.1007/s00394-022-03038-z","url":"https://doi.org/10.1007/s00394-022-03038-z","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m 2 ) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D 3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.","source_id":"source_1","support_kind":"candidate_source_row"},{"study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","year":2023,"doi":"10.3389/fendo.2023.1163671","url":"https://doi.org/10.3389/fendo.2023.1163671","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: Benefits of vitamin D in various cancers have been reported, but its effects on differentiated thyroid cancer (DTC) have not been established. We aimed to analyze the effect of vitamin D supplementation on the prognosis of DTC. METHODS: A retrospective observational cohort study was conducted on 9,739 DTC patients who underwent thyroidectomy from January 1997 to December 2016. Mortality was classified as all-cause, cancer-related, or thyroid cancer-related. Patients were divided into the \"VD group\" (supplemented with vitamin D) and the \"control group\" (without vitamin D supplementation). Propensity score matching was performed in a 1:1 ratio according to age, sex, tumor size, extrathyroidal extension (ETE), and lymph node metastasis (LNM) status, and 3,238 patients were assigned to each group. Kaplan-Meier curves, log-rank test and Cox proportional hazards regression analysis were performed. RESULTS: The follow-up period was 10.7 ± 4.2 years. Clinicopathological variables between two groups were similar except for all-cause ( p <0.001) and total cancer death ( p =0.001).","source_id":"source_2","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","year":2025,"doi":"10.1038/s41467-025-58721-6","url":"https://doi.org/10.1038/s41467-025-58721-6","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Observational and experimental evidence suggests that vitamin D plays a role in type 2 diabetes (T2D). However, prior randomized supplementation trials are limited to high-risk patients with prediabetes. Here we aim to evaluate whether vitamin D supplementation reduces risk of T2D in a general population of older US adults. The study design is an ancillary analysis (VITAL-T2D) of The Vitamin D and Omega-3 Trial (VITAL), a completed randomized, double-blind, placebo-controlled 2 × 2 trial of daily vitamin D 3 (cholecalciferol; 2000 IU/day) and omega-3 fatty acids (1 g/day) for the primary prevention of cancer and cardiovascular disease. We also conducted a systematic review and meta-analysis of vitamin D trial (≥1000 IU/d cholecalciferol) vs. placebo and T2D risk. We analyzed 22,220 adults with mean age 67.2 years (SD = 7.1) without T2D at enrollment (2011 to 2014), randomized to vitamin D 3 or placebo. Mean body mass index (BMI) was 27.5 kg/m 2 (SD = 5.3), with 51% female and 17% Black race/ethnicity. A subcohort (n = 911) attended in-person visits at baseline and 2 years for glycemic trait analyses. Our meta-analysis included 3 additional trials (5205 participants; 936 T2D cases).","source_id":"source_3","support_kind":"candidate_source_row"},{"study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","year":2022,"doi":"10.1002/jcsm.12976","url":"https://doi.org/10.1002/jcsm.12976","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis.","source_id":"source_4","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","year":2026,"doi":"10.1136/bmj-2025-087438","url":"https://doi.org/10.1136/bmj-2025-087438","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: To evaluate whether vitamin D supplementation improves live birth rates in women with polycystic ovary syndrome undergoing in vitro fertilisation. DESIGN: Multicentre, double blind, placebo controlled, randomised clinical trial. SETTING: 24 fertility centres in China. PARTICIPANTS: 876 participants with polycystic ovary syndrome undergoing in vitro fertilisation. INTERVENTIONS: Participants were randomised (1:1) to receive vitamin D 4000 IU/day or placebo before in vitro fertilisation for up to 90 days until the trigger day. MAIN OUTCOMES MEASURES: The primary outcome was live birth after the first embryo transfer. Secondary outcomes included serum 25-hydroxyvitamin D (25-OHD) levels on trigger day, pregnancy outcomes, fertility outcomes, and adverse events including severe ovarian hyperstimulation syndrome. RESULTS: Of 876 participants randomised, 865 were included in the modified intention-to-treat analysis, with 435 in the vitamin D group and 430 in the placebo group. Baseline mean serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively.","source_id":"source_5","support_kind":"candidate_source_row"}]},{"claim_id":"claim_8","claim":"Several unresolved questions pervade the literature on vitamin D supplementation effects, creating persistent uncertainty about clinical applicability. First, the dose-response relationship remains poorly characterized: some meta-analyses suggest benefits only at higher doses or in deficient populations, while others find no clear dose-response gradient. Second, the translation from mechanistic plausibility to clinical function is incomplete — for example, vitamin D supplementation effects on inflammatory markers such as C-reactive protein do not reliably predict improvements in hard outcomes. Third, population specificity appears critical, as vitamin D supplementation effects may differ substantially between those with documented deficiency versus sufficiency, between older and younger adults, and across racial and ethnic groups with varying baseline vitamin D status. Fourth, the question of optimal treatment duration remains unanswered, with trial durations ranging from weeks to years and no consensus on whether long-term continuous supplementation confers additional benefit or risk. Fifth, genetic polymorphisms in the vitamin D receptor may modify vitamin D supplementation effects, as suggested by recent pharmacogenomic analyses, but this evidence remains preliminary. Sixth, potential harms at high doses — including hypercalcemia, kidney stones, and vascular calcification — are often inadequately captured in trials designed to detect benefits rather than harms.","citation_support":[],"candidate_sources":[{"study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","year":2023,"doi":"10.1007/s00394-022-03038-z","url":"https://doi.org/10.1007/s00394-022-03038-z","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m 2 ) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D 3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.","source_id":"source_1","support_kind":"candidate_source_row"},{"study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","year":2023,"doi":"10.3389/fendo.2023.1163671","url":"https://doi.org/10.3389/fendo.2023.1163671","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: Benefits of vitamin D in various cancers have been reported, but its effects on differentiated thyroid cancer (DTC) have not been established. We aimed to analyze the effect of vitamin D supplementation on the prognosis of DTC. METHODS: A retrospective observational cohort study was conducted on 9,739 DTC patients who underwent thyroidectomy from January 1997 to December 2016. Mortality was classified as all-cause, cancer-related, or thyroid cancer-related. Patients were divided into the \"VD group\" (supplemented with vitamin D) and the \"control group\" (without vitamin D supplementation). Propensity score matching was performed in a 1:1 ratio according to age, sex, tumor size, extrathyroidal extension (ETE), and lymph node metastasis (LNM) status, and 3,238 patients were assigned to each group. Kaplan-Meier curves, log-rank test and Cox proportional hazards regression analysis were performed. RESULTS: The follow-up period was 10.7 ± 4.2 years. Clinicopathological variables between two groups were similar except for all-cause ( p <0.001) and total cancer death ( p =0.001).","source_id":"source_2","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","year":2025,"doi":"10.1038/s41467-025-58721-6","url":"https://doi.org/10.1038/s41467-025-58721-6","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Observational and experimental evidence suggests that vitamin D plays a role in type 2 diabetes (T2D). However, prior randomized supplementation trials are limited to high-risk patients with prediabetes. Here we aim to evaluate whether vitamin D supplementation reduces risk of T2D in a general population of older US adults. The study design is an ancillary analysis (VITAL-T2D) of The Vitamin D and Omega-3 Trial (VITAL), a completed randomized, double-blind, placebo-controlled 2 × 2 trial of daily vitamin D 3 (cholecalciferol; 2000 IU/day) and omega-3 fatty acids (1 g/day) for the primary prevention of cancer and cardiovascular disease. We also conducted a systematic review and meta-analysis of vitamin D trial (≥1000 IU/d cholecalciferol) vs. placebo and T2D risk. We analyzed 22,220 adults with mean age 67.2 years (SD = 7.1) without T2D at enrollment (2011 to 2014), randomized to vitamin D 3 or placebo. Mean body mass index (BMI) was 27.5 kg/m 2 (SD = 5.3), with 51% female and 17% Black race/ethnicity. A subcohort (n = 911) attended in-person visits at baseline and 2 years for glycemic trait analyses. Our meta-analysis included 3 additional trials (5205 participants; 936 T2D cases).","source_id":"source_3","support_kind":"candidate_source_row"},{"study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","year":2022,"doi":"10.1002/jcsm.12976","url":"https://doi.org/10.1002/jcsm.12976","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis.","source_id":"source_4","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","year":2026,"doi":"10.1136/bmj-2025-087438","url":"https://doi.org/10.1136/bmj-2025-087438","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: To evaluate whether vitamin D supplementation improves live birth rates in women with polycystic ovary syndrome undergoing in vitro fertilisation. DESIGN: Multicentre, double blind, placebo controlled, randomised clinical trial. SETTING: 24 fertility centres in China. PARTICIPANTS: 876 participants with polycystic ovary syndrome undergoing in vitro fertilisation. INTERVENTIONS: Participants were randomised (1:1) to receive vitamin D 4000 IU/day or placebo before in vitro fertilisation for up to 90 days until the trigger day. MAIN OUTCOMES MEASURES: The primary outcome was live birth after the first embryo transfer. Secondary outcomes included serum 25-hydroxyvitamin D (25-OHD) levels on trigger day, pregnancy outcomes, fertility outcomes, and adverse events including severe ovarian hyperstimulation syndrome. RESULTS: Of 876 participants randomised, 865 were included in the modified intention-to-treat analysis, with 435 in the vitamin D group and 430 in the placebo group. Baseline mean serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively.","source_id":"source_5","support_kind":"candidate_source_row"}]},{"claim_id":"claim_9","claim":"Preclinical and disease-model studies provide the mechanistic substrate for the vitamin D supplementation effects hypothesis, and the corpus under review spans cell-culture, rodent, and human tissue investigations that collectively implicate vitamin D in inflammation, metabolic regulation, and cellular resilience. The mechanistic plausibility of vitamin D as a modulator of mitochondrial function and oxidative stress is further supported by a randomized controlled trial showing that vitamin D supplementation improves cognitive function through reducing oxidative stress regulated by telomere length in older adults with mild cognitive impairment (Yang 2020, 12-month RCT). Collectively, these preclinical and mechanistic data establish that vitamin D supplementation effects on inflammation, insulin signaling, and cellular stress are biologically plausible, yet the pathway-level evidence does not consistently translate into disease-level outcomes, a disjunction that frames the clinical-trial literature reviewed below.","citation_support":[],"candidate_sources":[{"study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","year":2023,"doi":"10.1007/s00394-022-03038-z","url":"https://doi.org/10.1007/s00394-022-03038-z","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m 2 ) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D 3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.","source_id":"source_1","support_kind":"candidate_source_row"},{"study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","year":2023,"doi":"10.3389/fendo.2023.1163671","url":"https://doi.org/10.3389/fendo.2023.1163671","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: Benefits of vitamin D in various cancers have been reported, but its effects on differentiated thyroid cancer (DTC) have not been established. We aimed to analyze the effect of vitamin D supplementation on the prognosis of DTC. METHODS: A retrospective observational cohort study was conducted on 9,739 DTC patients who underwent thyroidectomy from January 1997 to December 2016. Mortality was classified as all-cause, cancer-related, or thyroid cancer-related. Patients were divided into the \"VD group\" (supplemented with vitamin D) and the \"control group\" (without vitamin D supplementation). Propensity score matching was performed in a 1:1 ratio according to age, sex, tumor size, extrathyroidal extension (ETE), and lymph node metastasis (LNM) status, and 3,238 patients were assigned to each group. Kaplan-Meier curves, log-rank test and Cox proportional hazards regression analysis were performed. RESULTS: The follow-up period was 10.7 ± 4.2 years. Clinicopathological variables between two groups were similar except for all-cause ( p <0.001) and total cancer death ( p =0.001).","source_id":"source_2","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","year":2025,"doi":"10.1038/s41467-025-58721-6","url":"https://doi.org/10.1038/s41467-025-58721-6","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Observational and experimental evidence suggests that vitamin D plays a role in type 2 diabetes (T2D). However, prior randomized supplementation trials are limited to high-risk patients with prediabetes. Here we aim to evaluate whether vitamin D supplementation reduces risk of T2D in a general population of older US adults. The study design is an ancillary analysis (VITAL-T2D) of The Vitamin D and Omega-3 Trial (VITAL), a completed randomized, double-blind, placebo-controlled 2 × 2 trial of daily vitamin D 3 (cholecalciferol; 2000 IU/day) and omega-3 fatty acids (1 g/day) for the primary prevention of cancer and cardiovascular disease. We also conducted a systematic review and meta-analysis of vitamin D trial (≥1000 IU/d cholecalciferol) vs. placebo and T2D risk. We analyzed 22,220 adults with mean age 67.2 years (SD = 7.1) without T2D at enrollment (2011 to 2014), randomized to vitamin D 3 or placebo. Mean body mass index (BMI) was 27.5 kg/m 2 (SD = 5.3), with 51% female and 17% Black race/ethnicity. A subcohort (n = 911) attended in-person visits at baseline and 2 years for glycemic trait analyses. Our meta-analysis included 3 additional trials (5205 participants; 936 T2D cases).","source_id":"source_3","support_kind":"candidate_source_row"},{"study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","year":2022,"doi":"10.1002/jcsm.12976","url":"https://doi.org/10.1002/jcsm.12976","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis.","source_id":"source_4","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","year":2026,"doi":"10.1136/bmj-2025-087438","url":"https://doi.org/10.1136/bmj-2025-087438","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: To evaluate whether vitamin D supplementation improves live birth rates in women with polycystic ovary syndrome undergoing in vitro fertilisation. DESIGN: Multicentre, double blind, placebo controlled, randomised clinical trial. SETTING: 24 fertility centres in China. PARTICIPANTS: 876 participants with polycystic ovary syndrome undergoing in vitro fertilisation. INTERVENTIONS: Participants were randomised (1:1) to receive vitamin D 4000 IU/day or placebo before in vitro fertilisation for up to 90 days until the trigger day. MAIN OUTCOMES MEASURES: The primary outcome was live birth after the first embryo transfer. Secondary outcomes included serum 25-hydroxyvitamin D (25-OHD) levels on trigger day, pregnancy outcomes, fertility outcomes, and adverse events including severe ovarian hyperstimulation syndrome. RESULTS: Of 876 participants randomised, 865 were included in the modified intention-to-treat analysis, with 435 in the vitamin D group and 430 in the placebo group. Baseline mean serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively.","source_id":"source_5","support_kind":"candidate_source_row"}]},{"claim_id":"claim_10","claim":"The biological rationale is treated as context rather than as clinical proof. Population fit, comparator alignment, clinical directness, follow-up length, ascertainment method, baseline risk, adherence, exposure dose, and external validity are kept separate during interpretation. The interpretation","citation_support":[],"candidate_sources":[{"study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","year":2023,"doi":"10.1007/s00394-022-03038-z","url":"https://doi.org/10.1007/s00394-022-03038-z","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m 2 ) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D 3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.","source_id":"source_1","support_kind":"candidate_source_row"},{"study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","year":2023,"doi":"10.3389/fendo.2023.1163671","url":"https://doi.org/10.3389/fendo.2023.1163671","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: Benefits of vitamin D in various cancers have been reported, but its effects on differentiated thyroid cancer (DTC) have not been established. We aimed to analyze the effect of vitamin D supplementation on the prognosis of DTC. METHODS: A retrospective observational cohort study was conducted on 9,739 DTC patients who underwent thyroidectomy from January 1997 to December 2016. Mortality was classified as all-cause, cancer-related, or thyroid cancer-related. Patients were divided into the \"VD group\" (supplemented with vitamin D) and the \"control group\" (without vitamin D supplementation). Propensity score matching was performed in a 1:1 ratio according to age, sex, tumor size, extrathyroidal extension (ETE), and lymph node metastasis (LNM) status, and 3,238 patients were assigned to each group. Kaplan-Meier curves, log-rank test and Cox proportional hazards regression analysis were performed. RESULTS: The follow-up period was 10.7 ± 4.2 years. Clinicopathological variables between two groups were similar except for all-cause ( p <0.001) and total cancer death ( p =0.001).","source_id":"source_2","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","year":2025,"doi":"10.1038/s41467-025-58721-6","url":"https://doi.org/10.1038/s41467-025-58721-6","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Observational and experimental evidence suggests that vitamin D plays a role in type 2 diabetes (T2D). However, prior randomized supplementation trials are limited to high-risk patients with prediabetes. Here we aim to evaluate whether vitamin D supplementation reduces risk of T2D in a general population of older US adults. The study design is an ancillary analysis (VITAL-T2D) of The Vitamin D and Omega-3 Trial (VITAL), a completed randomized, double-blind, placebo-controlled 2 × 2 trial of daily vitamin D 3 (cholecalciferol; 2000 IU/day) and omega-3 fatty acids (1 g/day) for the primary prevention of cancer and cardiovascular disease. We also conducted a systematic review and meta-analysis of vitamin D trial (≥1000 IU/d cholecalciferol) vs. placebo and T2D risk. We analyzed 22,220 adults with mean age 67.2 years (SD = 7.1) without T2D at enrollment (2011 to 2014), randomized to vitamin D 3 or placebo. Mean body mass index (BMI) was 27.5 kg/m 2 (SD = 5.3), with 51% female and 17% Black race/ethnicity. A subcohort (n = 911) attended in-person visits at baseline and 2 years for glycemic trait analyses. Our meta-analysis included 3 additional trials (5205 participants; 936 T2D cases).","source_id":"source_3","support_kind":"candidate_source_row"},{"study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","year":2022,"doi":"10.1002/jcsm.12976","url":"https://doi.org/10.1002/jcsm.12976","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis.","source_id":"source_4","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","year":2026,"doi":"10.1136/bmj-2025-087438","url":"https://doi.org/10.1136/bmj-2025-087438","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: To evaluate whether vitamin D supplementation improves live birth rates in women with polycystic ovary syndrome undergoing in vitro fertilisation. DESIGN: Multicentre, double blind, placebo controlled, randomised clinical trial. SETTING: 24 fertility centres in China. PARTICIPANTS: 876 participants with polycystic ovary syndrome undergoing in vitro fertilisation. INTERVENTIONS: Participants were randomised (1:1) to receive vitamin D 4000 IU/day or placebo before in vitro fertilisation for up to 90 days until the trigger day. MAIN OUTCOMES MEASURES: The primary outcome was live birth after the first embryo transfer. Secondary outcomes included serum 25-hydroxyvitamin D (25-OHD) levels on trigger day, pregnancy outcomes, fertility outcomes, and adverse events including severe ovarian hyperstimulation syndrome. RESULTS: Of 876 participants randomised, 865 were included in the modified intention-to-treat analysis, with 435 in the vitamin D group and 430 in the placebo group. Baseline mean serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively.","source_id":"source_5","support_kind":"candidate_source_row"}]},{"claim_id":"claim_11","claim":"The following fields were extracted from each included source: study design, population / cohort, intervention or exposure, comparator, outcome class, effect direction, effect size, confidence interval or credible interval, p-value, sample size, follow-up duration, risk-of-bias rating. Under the calibration rule, source verification in the public bundle is limited to reference-level metadata; exact statistics and effect directions are drawn from these structured extraction artifacts (the synthesis manifest, risk-of-bias appraisal, and claim registry) rather than from re-parsed full text.","citation_support":[],"candidate_sources":[{"study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","year":2023,"doi":"10.1007/s00394-022-03038-z","url":"https://doi.org/10.1007/s00394-022-03038-z","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m 2 ) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D 3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.","source_id":"source_1","support_kind":"candidate_source_row"},{"study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","year":2023,"doi":"10.3389/fendo.2023.1163671","url":"https://doi.org/10.3389/fendo.2023.1163671","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: Benefits of vitamin D in various cancers have been reported, but its effects on differentiated thyroid cancer (DTC) have not been established. We aimed to analyze the effect of vitamin D supplementation on the prognosis of DTC. METHODS: A retrospective observational cohort study was conducted on 9,739 DTC patients who underwent thyroidectomy from January 1997 to December 2016. Mortality was classified as all-cause, cancer-related, or thyroid cancer-related. Patients were divided into the \"VD group\" (supplemented with vitamin D) and the \"control group\" (without vitamin D supplementation). Propensity score matching was performed in a 1:1 ratio according to age, sex, tumor size, extrathyroidal extension (ETE), and lymph node metastasis (LNM) status, and 3,238 patients were assigned to each group. Kaplan-Meier curves, log-rank test and Cox proportional hazards regression analysis were performed. RESULTS: The follow-up period was 10.7 ± 4.2 years. Clinicopathological variables between two groups were similar except for all-cause ( p <0.001) and total cancer death ( p =0.001).","source_id":"source_2","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","year":2025,"doi":"10.1038/s41467-025-58721-6","url":"https://doi.org/10.1038/s41467-025-58721-6","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Observational and experimental evidence suggests that vitamin D plays a role in type 2 diabetes (T2D). However, prior randomized supplementation trials are limited to high-risk patients with prediabetes. Here we aim to evaluate whether vitamin D supplementation reduces risk of T2D in a general population of older US adults. The study design is an ancillary analysis (VITAL-T2D) of The Vitamin D and Omega-3 Trial (VITAL), a completed randomized, double-blind, placebo-controlled 2 × 2 trial of daily vitamin D 3 (cholecalciferol; 2000 IU/day) and omega-3 fatty acids (1 g/day) for the primary prevention of cancer and cardiovascular disease. We also conducted a systematic review and meta-analysis of vitamin D trial (≥1000 IU/d cholecalciferol) vs. placebo and T2D risk. We analyzed 22,220 adults with mean age 67.2 years (SD = 7.1) without T2D at enrollment (2011 to 2014), randomized to vitamin D 3 or placebo. Mean body mass index (BMI) was 27.5 kg/m 2 (SD = 5.3), with 51% female and 17% Black race/ethnicity. A subcohort (n = 911) attended in-person visits at baseline and 2 years for glycemic trait analyses. Our meta-analysis included 3 additional trials (5205 participants; 936 T2D cases).","source_id":"source_3","support_kind":"candidate_source_row"},{"study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","year":2022,"doi":"10.1002/jcsm.12976","url":"https://doi.org/10.1002/jcsm.12976","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis.","source_id":"source_4","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","year":2026,"doi":"10.1136/bmj-2025-087438","url":"https://doi.org/10.1136/bmj-2025-087438","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: To evaluate whether vitamin D supplementation improves live birth rates in women with polycystic ovary syndrome undergoing in vitro fertilisation. DESIGN: Multicentre, double blind, placebo controlled, randomised clinical trial. SETTING: 24 fertility centres in China. PARTICIPANTS: 876 participants with polycystic ovary syndrome undergoing in vitro fertilisation. INTERVENTIONS: Participants were randomised (1:1) to receive vitamin D 4000 IU/day or placebo before in vitro fertilisation for up to 90 days until the trigger day. MAIN OUTCOMES MEASURES: The primary outcome was live birth after the first embryo transfer. Secondary outcomes included serum 25-hydroxyvitamin D (25-OHD) levels on trigger day, pregnancy outcomes, fertility outcomes, and adverse events including severe ovarian hyperstimulation syndrome. RESULTS: Of 876 participants randomised, 865 were included in the modified intention-to-treat analysis, with 435 in the vitamin D group and 430 in the placebo group. Baseline mean serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively.","source_id":"source_5","support_kind":"candidate_source_row"}]},{"claim_id":"claim_12","claim":"Per-source risk-of-bias was rated using design-appropriate Cochrane RoB-2 (RCTs), ROBINS-I (non-randomised studies), and AMSTAR-2 (systematic reviews / meta-analyses). Ratings recorded in `risk_of_bias.json`.","citation_support":[],"candidate_sources":[{"study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","year":2023,"doi":"10.1007/s00394-022-03038-z","url":"https://doi.org/10.1007/s00394-022-03038-z","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m 2 ) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D 3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.","source_id":"source_1","support_kind":"candidate_source_row"},{"study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","year":2023,"doi":"10.3389/fendo.2023.1163671","url":"https://doi.org/10.3389/fendo.2023.1163671","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: Benefits of vitamin D in various cancers have been reported, but its effects on differentiated thyroid cancer (DTC) have not been established. We aimed to analyze the effect of vitamin D supplementation on the prognosis of DTC. METHODS: A retrospective observational cohort study was conducted on 9,739 DTC patients who underwent thyroidectomy from January 1997 to December 2016. Mortality was classified as all-cause, cancer-related, or thyroid cancer-related. Patients were divided into the \"VD group\" (supplemented with vitamin D) and the \"control group\" (without vitamin D supplementation). Propensity score matching was performed in a 1:1 ratio according to age, sex, tumor size, extrathyroidal extension (ETE), and lymph node metastasis (LNM) status, and 3,238 patients were assigned to each group. Kaplan-Meier curves, log-rank test and Cox proportional hazards regression analysis were performed. RESULTS: The follow-up period was 10.7 ± 4.2 years. Clinicopathological variables between two groups were similar except for all-cause ( p <0.001) and total cancer death ( p =0.001).","source_id":"source_2","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","year":2025,"doi":"10.1038/s41467-025-58721-6","url":"https://doi.org/10.1038/s41467-025-58721-6","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Observational and experimental evidence suggests that vitamin D plays a role in type 2 diabetes (T2D). However, prior randomized supplementation trials are limited to high-risk patients with prediabetes. Here we aim to evaluate whether vitamin D supplementation reduces risk of T2D in a general population of older US adults. The study design is an ancillary analysis (VITAL-T2D) of The Vitamin D and Omega-3 Trial (VITAL), a completed randomized, double-blind, placebo-controlled 2 × 2 trial of daily vitamin D 3 (cholecalciferol; 2000 IU/day) and omega-3 fatty acids (1 g/day) for the primary prevention of cancer and cardiovascular disease. We also conducted a systematic review and meta-analysis of vitamin D trial (≥1000 IU/d cholecalciferol) vs. placebo and T2D risk. We analyzed 22,220 adults with mean age 67.2 years (SD = 7.1) without T2D at enrollment (2011 to 2014), randomized to vitamin D 3 or placebo. Mean body mass index (BMI) was 27.5 kg/m 2 (SD = 5.3), with 51% female and 17% Black race/ethnicity. A subcohort (n = 911) attended in-person visits at baseline and 2 years for glycemic trait analyses. Our meta-analysis included 3 additional trials (5205 participants; 936 T2D cases).","source_id":"source_3","support_kind":"candidate_source_row"},{"study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","year":2022,"doi":"10.1002/jcsm.12976","url":"https://doi.org/10.1002/jcsm.12976","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis.","source_id":"source_4","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","year":2026,"doi":"10.1136/bmj-2025-087438","url":"https://doi.org/10.1136/bmj-2025-087438","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: To evaluate whether vitamin D supplementation improves live birth rates in women with polycystic ovary syndrome undergoing in vitro fertilisation. DESIGN: Multicentre, double blind, placebo controlled, randomised clinical trial. SETTING: 24 fertility centres in China. PARTICIPANTS: 876 participants with polycystic ovary syndrome undergoing in vitro fertilisation. INTERVENTIONS: Participants were randomised (1:1) to receive vitamin D 4000 IU/day or placebo before in vitro fertilisation for up to 90 days until the trigger day. MAIN OUTCOMES MEASURES: The primary outcome was live birth after the first embryo transfer. Secondary outcomes included serum 25-hydroxyvitamin D (25-OHD) levels on trigger day, pregnancy outcomes, fertility outcomes, and adverse events including severe ovarian hyperstimulation syndrome. RESULTS: Of 876 participants randomised, 865 were included in the modified intention-to-treat analysis, with 435 in the vitamin D group and 430 in the placebo group. Baseline mean serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively.","source_id":"source_5","support_kind":"candidate_source_row"}]},{"claim_id":"claim_13","claim":"Evidence-tension synthesis: claims grouped by outcome class (cardiometabolic, contextual adjacent evidence, deficiency prevalence, dosing and pharmacokinetics, frailty, immune, longevity, muscle function); within-class agreement, disagreement, and directness gaps surfaced explicitly. Quantitative pooling applied only where ≥3 sources reported a comparable endpoint with extractable effect estimates.","citation_support":[],"candidate_sources":[{"study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","year":2023,"doi":"10.1007/s00394-022-03038-z","url":"https://doi.org/10.1007/s00394-022-03038-z","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m 2 ) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D 3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.","source_id":"source_1","support_kind":"candidate_source_row"},{"study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","year":2023,"doi":"10.3389/fendo.2023.1163671","url":"https://doi.org/10.3389/fendo.2023.1163671","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: Benefits of vitamin D in various cancers have been reported, but its effects on differentiated thyroid cancer (DTC) have not been established. We aimed to analyze the effect of vitamin D supplementation on the prognosis of DTC. METHODS: A retrospective observational cohort study was conducted on 9,739 DTC patients who underwent thyroidectomy from January 1997 to December 2016. Mortality was classified as all-cause, cancer-related, or thyroid cancer-related. Patients were divided into the \"VD group\" (supplemented with vitamin D) and the \"control group\" (without vitamin D supplementation). Propensity score matching was performed in a 1:1 ratio according to age, sex, tumor size, extrathyroidal extension (ETE), and lymph node metastasis (LNM) status, and 3,238 patients were assigned to each group. Kaplan-Meier curves, log-rank test and Cox proportional hazards regression analysis were performed. RESULTS: The follow-up period was 10.7 ± 4.2 years. Clinicopathological variables between two groups were similar except for all-cause ( p <0.001) and total cancer death ( p =0.001).","source_id":"source_2","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","year":2025,"doi":"10.1038/s41467-025-58721-6","url":"https://doi.org/10.1038/s41467-025-58721-6","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Observational and experimental evidence suggests that vitamin D plays a role in type 2 diabetes (T2D). However, prior randomized supplementation trials are limited to high-risk patients with prediabetes. Here we aim to evaluate whether vitamin D supplementation reduces risk of T2D in a general population of older US adults. The study design is an ancillary analysis (VITAL-T2D) of The Vitamin D and Omega-3 Trial (VITAL), a completed randomized, double-blind, placebo-controlled 2 × 2 trial of daily vitamin D 3 (cholecalciferol; 2000 IU/day) and omega-3 fatty acids (1 g/day) for the primary prevention of cancer and cardiovascular disease. We also conducted a systematic review and meta-analysis of vitamin D trial (≥1000 IU/d cholecalciferol) vs. placebo and T2D risk. We analyzed 22,220 adults with mean age 67.2 years (SD = 7.1) without T2D at enrollment (2011 to 2014), randomized to vitamin D 3 or placebo. Mean body mass index (BMI) was 27.5 kg/m 2 (SD = 5.3), with 51% female and 17% Black race/ethnicity. A subcohort (n = 911) attended in-person visits at baseline and 2 years for glycemic trait analyses. Our meta-analysis included 3 additional trials (5205 participants; 936 T2D cases).","source_id":"source_3","support_kind":"candidate_source_row"},{"study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","year":2022,"doi":"10.1002/jcsm.12976","url":"https://doi.org/10.1002/jcsm.12976","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis.","source_id":"source_4","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","year":2026,"doi":"10.1136/bmj-2025-087438","url":"https://doi.org/10.1136/bmj-2025-087438","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: To evaluate whether vitamin D supplementation improves live birth rates in women with polycystic ovary syndrome undergoing in vitro fertilisation. DESIGN: Multicentre, double blind, placebo controlled, randomised clinical trial. SETTING: 24 fertility centres in China. PARTICIPANTS: 876 participants with polycystic ovary syndrome undergoing in vitro fertilisation. INTERVENTIONS: Participants were randomised (1:1) to receive vitamin D 4000 IU/day or placebo before in vitro fertilisation for up to 90 days until the trigger day. MAIN OUTCOMES MEASURES: The primary outcome was live birth after the first embryo transfer. Secondary outcomes included serum 25-hydroxyvitamin D (25-OHD) levels on trigger day, pregnancy outcomes, fertility outcomes, and adverse events including severe ovarian hyperstimulation syndrome. RESULTS: Of 876 participants randomised, 865 were included in the modified intention-to-treat analysis, with 435 in the vitamin D group and 430 in the placebo group. Baseline mean serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively.","source_id":"source_5","support_kind":"candidate_source_row"}]},{"claim_id":"claim_14","claim":"Source retrieval, claim extraction, evidence routing, and prose drafting were assisted by large language models under a deterministic audit-trail protocol. Every manuscript claim is traceable to a source record in the supplementary `manifest.json`. Final eligibility and interpretation decisions are author-verified.","citation_support":[],"candidate_sources":[{"study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","year":2023,"doi":"10.1007/s00394-022-03038-z","url":"https://doi.org/10.1007/s00394-022-03038-z","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m 2 ) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D 3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.","source_id":"source_1","support_kind":"candidate_source_row"},{"study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","year":2023,"doi":"10.3389/fendo.2023.1163671","url":"https://doi.org/10.3389/fendo.2023.1163671","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: Benefits of vitamin D in various cancers have been reported, but its effects on differentiated thyroid cancer (DTC) have not been established. We aimed to analyze the effect of vitamin D supplementation on the prognosis of DTC. METHODS: A retrospective observational cohort study was conducted on 9,739 DTC patients who underwent thyroidectomy from January 1997 to December 2016. Mortality was classified as all-cause, cancer-related, or thyroid cancer-related. Patients were divided into the \"VD group\" (supplemented with vitamin D) and the \"control group\" (without vitamin D supplementation). Propensity score matching was performed in a 1:1 ratio according to age, sex, tumor size, extrathyroidal extension (ETE), and lymph node metastasis (LNM) status, and 3,238 patients were assigned to each group. Kaplan-Meier curves, log-rank test and Cox proportional hazards regression analysis were performed. RESULTS: The follow-up period was 10.7 ± 4.2 years. Clinicopathological variables between two groups were similar except for all-cause ( p <0.001) and total cancer death ( p =0.001).","source_id":"source_2","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","year":2025,"doi":"10.1038/s41467-025-58721-6","url":"https://doi.org/10.1038/s41467-025-58721-6","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Observational and experimental evidence suggests that vitamin D plays a role in type 2 diabetes (T2D). However, prior randomized supplementation trials are limited to high-risk patients with prediabetes. Here we aim to evaluate whether vitamin D supplementation reduces risk of T2D in a general population of older US adults. The study design is an ancillary analysis (VITAL-T2D) of The Vitamin D and Omega-3 Trial (VITAL), a completed randomized, double-blind, placebo-controlled 2 × 2 trial of daily vitamin D 3 (cholecalciferol; 2000 IU/day) and omega-3 fatty acids (1 g/day) for the primary prevention of cancer and cardiovascular disease. We also conducted a systematic review and meta-analysis of vitamin D trial (≥1000 IU/d cholecalciferol) vs. placebo and T2D risk. We analyzed 22,220 adults with mean age 67.2 years (SD = 7.1) without T2D at enrollment (2011 to 2014), randomized to vitamin D 3 or placebo. Mean body mass index (BMI) was 27.5 kg/m 2 (SD = 5.3), with 51% female and 17% Black race/ethnicity. A subcohort (n = 911) attended in-person visits at baseline and 2 years for glycemic trait analyses. Our meta-analysis included 3 additional trials (5205 participants; 936 T2D cases).","source_id":"source_3","support_kind":"candidate_source_row"},{"study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","year":2022,"doi":"10.1002/jcsm.12976","url":"https://doi.org/10.1002/jcsm.12976","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis.","source_id":"source_4","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","year":2026,"doi":"10.1136/bmj-2025-087438","url":"https://doi.org/10.1136/bmj-2025-087438","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: To evaluate whether vitamin D supplementation improves live birth rates in women with polycystic ovary syndrome undergoing in vitro fertilisation. DESIGN: Multicentre, double blind, placebo controlled, randomised clinical trial. SETTING: 24 fertility centres in China. PARTICIPANTS: 876 participants with polycystic ovary syndrome undergoing in vitro fertilisation. INTERVENTIONS: Participants were randomised (1:1) to receive vitamin D 4000 IU/day or placebo before in vitro fertilisation for up to 90 days until the trigger day. MAIN OUTCOMES MEASURES: The primary outcome was live birth after the first embryo transfer. Secondary outcomes included serum 25-hydroxyvitamin D (25-OHD) levels on trigger day, pregnancy outcomes, fertility outcomes, and adverse events including severe ovarian hyperstimulation syndrome. RESULTS: Of 876 participants randomised, 865 were included in the modified intention-to-treat analysis, with 435 in the vitamin D group and 430 in the placebo group. Baseline mean serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively.","source_id":"source_5","support_kind":"candidate_source_row"}]},{"claim_id":"claim_15","claim":"Outcome-class note:** Contextual Adjacent Evidence denotes background, boundary-condition, or adjacent-outcome sources. It is not pooled with direct outcome evidence; these sources bound scope, safety, methods, and translation rather than serving as equal-weight support for the main efficacy claim.","citation_support":[],"candidate_sources":[{"study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","year":2023,"doi":"10.1007/s00394-022-03038-z","url":"https://doi.org/10.1007/s00394-022-03038-z","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m 2 ) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D 3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.","source_id":"source_1","support_kind":"candidate_source_row"},{"study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","year":2023,"doi":"10.3389/fendo.2023.1163671","url":"https://doi.org/10.3389/fendo.2023.1163671","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: Benefits of vitamin D in various cancers have been reported, but its effects on differentiated thyroid cancer (DTC) have not been established. We aimed to analyze the effect of vitamin D supplementation on the prognosis of DTC. METHODS: A retrospective observational cohort study was conducted on 9,739 DTC patients who underwent thyroidectomy from January 1997 to December 2016. Mortality was classified as all-cause, cancer-related, or thyroid cancer-related. Patients were divided into the \"VD group\" (supplemented with vitamin D) and the \"control group\" (without vitamin D supplementation). Propensity score matching was performed in a 1:1 ratio according to age, sex, tumor size, extrathyroidal extension (ETE), and lymph node metastasis (LNM) status, and 3,238 patients were assigned to each group. Kaplan-Meier curves, log-rank test and Cox proportional hazards regression analysis were performed. RESULTS: The follow-up period was 10.7 ± 4.2 years. Clinicopathological variables between two groups were similar except for all-cause ( p <0.001) and total cancer death ( p =0.001).","source_id":"source_2","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","year":2025,"doi":"10.1038/s41467-025-58721-6","url":"https://doi.org/10.1038/s41467-025-58721-6","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Observational and experimental evidence suggests that vitamin D plays a role in type 2 diabetes (T2D). However, prior randomized supplementation trials are limited to high-risk patients with prediabetes. Here we aim to evaluate whether vitamin D supplementation reduces risk of T2D in a general population of older US adults. The study design is an ancillary analysis (VITAL-T2D) of The Vitamin D and Omega-3 Trial (VITAL), a completed randomized, double-blind, placebo-controlled 2 × 2 trial of daily vitamin D 3 (cholecalciferol; 2000 IU/day) and omega-3 fatty acids (1 g/day) for the primary prevention of cancer and cardiovascular disease. We also conducted a systematic review and meta-analysis of vitamin D trial (≥1000 IU/d cholecalciferol) vs. placebo and T2D risk. We analyzed 22,220 adults with mean age 67.2 years (SD = 7.1) without T2D at enrollment (2011 to 2014), randomized to vitamin D 3 or placebo. Mean body mass index (BMI) was 27.5 kg/m 2 (SD = 5.3), with 51% female and 17% Black race/ethnicity. A subcohort (n = 911) attended in-person visits at baseline and 2 years for glycemic trait analyses. Our meta-analysis included 3 additional trials (5205 participants; 936 T2D cases).","source_id":"source_3","support_kind":"candidate_source_row"},{"study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","year":2022,"doi":"10.1002/jcsm.12976","url":"https://doi.org/10.1002/jcsm.12976","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis.","source_id":"source_4","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","year":2026,"doi":"10.1136/bmj-2025-087438","url":"https://doi.org/10.1136/bmj-2025-087438","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: To evaluate whether vitamin D supplementation improves live birth rates in women with polycystic ovary syndrome undergoing in vitro fertilisation. DESIGN: Multicentre, double blind, placebo controlled, randomised clinical trial. SETTING: 24 fertility centres in China. PARTICIPANTS: 876 participants with polycystic ovary syndrome undergoing in vitro fertilisation. INTERVENTIONS: Participants were randomised (1:1) to receive vitamin D 4000 IU/day or placebo before in vitro fertilisation for up to 90 days until the trigger day. MAIN OUTCOMES MEASURES: The primary outcome was live birth after the first embryo transfer. Secondary outcomes included serum 25-hydroxyvitamin D (25-OHD) levels on trigger day, pregnancy outcomes, fertility outcomes, and adverse events including severe ovarian hyperstimulation syndrome. RESULTS: Of 876 participants randomised, 865 were included in the modified intention-to-treat analysis, with 435 in the vitamin D group and 430 in the placebo group. Baseline mean serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively.","source_id":"source_5","support_kind":"candidate_source_row"}]},{"claim_id":"claim_16","claim":"| Evidence domain | Corpus slice | Strongest signal | Directness | Main limitation |","citation_support":[],"candidate_sources":[{"study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","year":2023,"doi":"10.1007/s00394-022-03038-z","url":"https://doi.org/10.1007/s00394-022-03038-z","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m 2 ) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D 3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.","source_id":"source_1","support_kind":"candidate_source_row"},{"study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","year":2023,"doi":"10.3389/fendo.2023.1163671","url":"https://doi.org/10.3389/fendo.2023.1163671","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: Benefits of vitamin D in various cancers have been reported, but its effects on differentiated thyroid cancer (DTC) have not been established. We aimed to analyze the effect of vitamin D supplementation on the prognosis of DTC. METHODS: A retrospective observational cohort study was conducted on 9,739 DTC patients who underwent thyroidectomy from January 1997 to December 2016. Mortality was classified as all-cause, cancer-related, or thyroid cancer-related. Patients were divided into the \"VD group\" (supplemented with vitamin D) and the \"control group\" (without vitamin D supplementation). Propensity score matching was performed in a 1:1 ratio according to age, sex, tumor size, extrathyroidal extension (ETE), and lymph node metastasis (LNM) status, and 3,238 patients were assigned to each group. Kaplan-Meier curves, log-rank test and Cox proportional hazards regression analysis were performed. RESULTS: The follow-up period was 10.7 ± 4.2 years. Clinicopathological variables between two groups were similar except for all-cause ( p <0.001) and total cancer death ( p =0.001).","source_id":"source_2","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","year":2025,"doi":"10.1038/s41467-025-58721-6","url":"https://doi.org/10.1038/s41467-025-58721-6","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Observational and experimental evidence suggests that vitamin D plays a role in type 2 diabetes (T2D). However, prior randomized supplementation trials are limited to high-risk patients with prediabetes. Here we aim to evaluate whether vitamin D supplementation reduces risk of T2D in a general population of older US adults. The study design is an ancillary analysis (VITAL-T2D) of The Vitamin D and Omega-3 Trial (VITAL), a completed randomized, double-blind, placebo-controlled 2 × 2 trial of daily vitamin D 3 (cholecalciferol; 2000 IU/day) and omega-3 fatty acids (1 g/day) for the primary prevention of cancer and cardiovascular disease. We also conducted a systematic review and meta-analysis of vitamin D trial (≥1000 IU/d cholecalciferol) vs. placebo and T2D risk. We analyzed 22,220 adults with mean age 67.2 years (SD = 7.1) without T2D at enrollment (2011 to 2014), randomized to vitamin D 3 or placebo. Mean body mass index (BMI) was 27.5 kg/m 2 (SD = 5.3), with 51% female and 17% Black race/ethnicity. A subcohort (n = 911) attended in-person visits at baseline and 2 years for glycemic trait analyses. Our meta-analysis included 3 additional trials (5205 participants; 936 T2D cases).","source_id":"source_3","support_kind":"candidate_source_row"},{"study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","year":2022,"doi":"10.1002/jcsm.12976","url":"https://doi.org/10.1002/jcsm.12976","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis.","source_id":"source_4","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","year":2026,"doi":"10.1136/bmj-2025-087438","url":"https://doi.org/10.1136/bmj-2025-087438","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: To evaluate whether vitamin D supplementation improves live birth rates in women with polycystic ovary syndrome undergoing in vitro fertilisation. DESIGN: Multicentre, double blind, placebo controlled, randomised clinical trial. SETTING: 24 fertility centres in China. PARTICIPANTS: 876 participants with polycystic ovary syndrome undergoing in vitro fertilisation. INTERVENTIONS: Participants were randomised (1:1) to receive vitamin D 4000 IU/day or placebo before in vitro fertilisation for up to 90 days until the trigger day. MAIN OUTCOMES MEASURES: The primary outcome was live birth after the first embryo transfer. Secondary outcomes included serum 25-hydroxyvitamin D (25-OHD) levels on trigger day, pregnancy outcomes, fertility outcomes, and adverse events including severe ovarian hyperstimulation syndrome. RESULTS: Of 876 participants randomised, 865 were included in the modified intention-to-treat analysis, with 435 in the vitamin D group and 430 in the placebo group. Baseline mean serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively.","source_id":"source_5","support_kind":"candidate_source_row"}]},{"claim_id":"claim_17","claim":"| Contextual Adjacent Evidence | n=3; claims=159 | unclear signal in 2/3 sources | 3 review | limited corpus depth in this outcome class |","citation_support":[],"candidate_sources":[{"study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","year":2023,"doi":"10.1007/s00394-022-03038-z","url":"https://doi.org/10.1007/s00394-022-03038-z","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m 2 ) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D 3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.","source_id":"source_1","support_kind":"candidate_source_row"},{"study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","year":2023,"doi":"10.3389/fendo.2023.1163671","url":"https://doi.org/10.3389/fendo.2023.1163671","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: Benefits of vitamin D in various cancers have been reported, but its effects on differentiated thyroid cancer (DTC) have not been established. We aimed to analyze the effect of vitamin D supplementation on the prognosis of DTC. METHODS: A retrospective observational cohort study was conducted on 9,739 DTC patients who underwent thyroidectomy from January 1997 to December 2016. Mortality was classified as all-cause, cancer-related, or thyroid cancer-related. Patients were divided into the \"VD group\" (supplemented with vitamin D) and the \"control group\" (without vitamin D supplementation). Propensity score matching was performed in a 1:1 ratio according to age, sex, tumor size, extrathyroidal extension (ETE), and lymph node metastasis (LNM) status, and 3,238 patients were assigned to each group. Kaplan-Meier curves, log-rank test and Cox proportional hazards regression analysis were performed. RESULTS: The follow-up period was 10.7 ± 4.2 years. Clinicopathological variables between two groups were similar except for all-cause ( p <0.001) and total cancer death ( p =0.001).","source_id":"source_2","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","year":2025,"doi":"10.1038/s41467-025-58721-6","url":"https://doi.org/10.1038/s41467-025-58721-6","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Observational and experimental evidence suggests that vitamin D plays a role in type 2 diabetes (T2D). However, prior randomized supplementation trials are limited to high-risk patients with prediabetes. Here we aim to evaluate whether vitamin D supplementation reduces risk of T2D in a general population of older US adults. The study design is an ancillary analysis (VITAL-T2D) of The Vitamin D and Omega-3 Trial (VITAL), a completed randomized, double-blind, placebo-controlled 2 × 2 trial of daily vitamin D 3 (cholecalciferol; 2000 IU/day) and omega-3 fatty acids (1 g/day) for the primary prevention of cancer and cardiovascular disease. We also conducted a systematic review and meta-analysis of vitamin D trial (≥1000 IU/d cholecalciferol) vs. placebo and T2D risk. We analyzed 22,220 adults with mean age 67.2 years (SD = 7.1) without T2D at enrollment (2011 to 2014), randomized to vitamin D 3 or placebo. Mean body mass index (BMI) was 27.5 kg/m 2 (SD = 5.3), with 51% female and 17% Black race/ethnicity. A subcohort (n = 911) attended in-person visits at baseline and 2 years for glycemic trait analyses. Our meta-analysis included 3 additional trials (5205 participants; 936 T2D cases).","source_id":"source_3","support_kind":"candidate_source_row"},{"study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","year":2022,"doi":"10.1002/jcsm.12976","url":"https://doi.org/10.1002/jcsm.12976","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis.","source_id":"source_4","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","year":2026,"doi":"10.1136/bmj-2025-087438","url":"https://doi.org/10.1136/bmj-2025-087438","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: To evaluate whether vitamin D supplementation improves live birth rates in women with polycystic ovary syndrome undergoing in vitro fertilisation. DESIGN: Multicentre, double blind, placebo controlled, randomised clinical trial. SETTING: 24 fertility centres in China. PARTICIPANTS: 876 participants with polycystic ovary syndrome undergoing in vitro fertilisation. INTERVENTIONS: Participants were randomised (1:1) to receive vitamin D 4000 IU/day or placebo before in vitro fertilisation for up to 90 days until the trigger day. MAIN OUTCOMES MEASURES: The primary outcome was live birth after the first embryo transfer. Secondary outcomes included serum 25-hydroxyvitamin D (25-OHD) levels on trigger day, pregnancy outcomes, fertility outcomes, and adverse events including severe ovarian hyperstimulation syndrome. RESULTS: Of 876 participants randomised, 865 were included in the modified intention-to-treat analysis, with 435 in the vitamin D group and 430 in the placebo group. Baseline mean serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively.","source_id":"source_5","support_kind":"candidate_source_row"}]},{"claim_id":"claim_18","claim":"Contextual Adjacent Evidence: n=3; claims=159; mixed signal in 2/3 sources | directness: 3 review; main limitation: no direct clinical anchor.","citation_support":[],"candidate_sources":[{"study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","year":2023,"doi":"10.1007/s00394-022-03038-z","url":"https://doi.org/10.1007/s00394-022-03038-z","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m 2 ) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D 3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.","source_id":"source_1","support_kind":"candidate_source_row"},{"study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","year":2023,"doi":"10.3389/fendo.2023.1163671","url":"https://doi.org/10.3389/fendo.2023.1163671","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: Benefits of vitamin D in various cancers have been reported, but its effects on differentiated thyroid cancer (DTC) have not been established. We aimed to analyze the effect of vitamin D supplementation on the prognosis of DTC. METHODS: A retrospective observational cohort study was conducted on 9,739 DTC patients who underwent thyroidectomy from January 1997 to December 2016. Mortality was classified as all-cause, cancer-related, or thyroid cancer-related. Patients were divided into the \"VD group\" (supplemented with vitamin D) and the \"control group\" (without vitamin D supplementation). Propensity score matching was performed in a 1:1 ratio according to age, sex, tumor size, extrathyroidal extension (ETE), and lymph node metastasis (LNM) status, and 3,238 patients were assigned to each group. Kaplan-Meier curves, log-rank test and Cox proportional hazards regression analysis were performed. RESULTS: The follow-up period was 10.7 ± 4.2 years. Clinicopathological variables between two groups were similar except for all-cause ( p <0.001) and total cancer death ( p =0.001).","source_id":"source_2","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","year":2025,"doi":"10.1038/s41467-025-58721-6","url":"https://doi.org/10.1038/s41467-025-58721-6","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Observational and experimental evidence suggests that vitamin D plays a role in type 2 diabetes (T2D). However, prior randomized supplementation trials are limited to high-risk patients with prediabetes. Here we aim to evaluate whether vitamin D supplementation reduces risk of T2D in a general population of older US adults. The study design is an ancillary analysis (VITAL-T2D) of The Vitamin D and Omega-3 Trial (VITAL), a completed randomized, double-blind, placebo-controlled 2 × 2 trial of daily vitamin D 3 (cholecalciferol; 2000 IU/day) and omega-3 fatty acids (1 g/day) for the primary prevention of cancer and cardiovascular disease. We also conducted a systematic review and meta-analysis of vitamin D trial (≥1000 IU/d cholecalciferol) vs. placebo and T2D risk. We analyzed 22,220 adults with mean age 67.2 years (SD = 7.1) without T2D at enrollment (2011 to 2014), randomized to vitamin D 3 or placebo. Mean body mass index (BMI) was 27.5 kg/m 2 (SD = 5.3), with 51% female and 17% Black race/ethnicity. A subcohort (n = 911) attended in-person visits at baseline and 2 years for glycemic trait analyses. Our meta-analysis included 3 additional trials (5205 participants; 936 T2D cases).","source_id":"source_3","support_kind":"candidate_source_row"},{"study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","year":2022,"doi":"10.1002/jcsm.12976","url":"https://doi.org/10.1002/jcsm.12976","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis.","source_id":"source_4","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","year":2026,"doi":"10.1136/bmj-2025-087438","url":"https://doi.org/10.1136/bmj-2025-087438","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: To evaluate whether vitamin D supplementation improves live birth rates in women with polycystic ovary syndrome undergoing in vitro fertilisation. DESIGN: Multicentre, double blind, placebo controlled, randomised clinical trial. SETTING: 24 fertility centres in China. PARTICIPANTS: 876 participants with polycystic ovary syndrome undergoing in vitro fertilisation. INTERVENTIONS: Participants were randomised (1:1) to receive vitamin D 4000 IU/day or placebo before in vitro fertilisation for up to 90 days until the trigger day. MAIN OUTCOMES MEASURES: The primary outcome was live birth after the first embryo transfer. Secondary outcomes included serum 25-hydroxyvitamin D (25-OHD) levels on trigger day, pregnancy outcomes, fertility outcomes, and adverse events including severe ovarian hyperstimulation syndrome. RESULTS: Of 876 participants randomised, 865 were included in the modified intention-to-treat analysis, with 435 in the vitamin D group and 430 in the placebo group. Baseline mean serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively.","source_id":"source_5","support_kind":"candidate_source_row"}]},{"claim_id":"claim_19","claim":"The evidence base for vitamin D supplementation and cardiometabolic endpoints includes a large randomized trial, a mechanistic RCT, and two systematic reviews. Peng 2025 performed an integrated transcriptomic and meta-analysis focusing on overweight or obese adults (BMI ≥ 25 kg/m²), while Migliorini 2025 provided a level I systematic review of vitamin D and calcium in women with postmenopausal osteoporosis.","citation_support":[],"candidate_sources":[{"study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","year":2023,"doi":"10.1007/s00394-022-03038-z","url":"https://doi.org/10.1007/s00394-022-03038-z","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m 2 ) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D 3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.","source_id":"source_1","support_kind":"candidate_source_row"},{"study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","year":2023,"doi":"10.3389/fendo.2023.1163671","url":"https://doi.org/10.3389/fendo.2023.1163671","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: Benefits of vitamin D in various cancers have been reported, but its effects on differentiated thyroid cancer (DTC) have not been established. We aimed to analyze the effect of vitamin D supplementation on the prognosis of DTC. METHODS: A retrospective observational cohort study was conducted on 9,739 DTC patients who underwent thyroidectomy from January 1997 to December 2016. Mortality was classified as all-cause, cancer-related, or thyroid cancer-related. Patients were divided into the \"VD group\" (supplemented with vitamin D) and the \"control group\" (without vitamin D supplementation). Propensity score matching was performed in a 1:1 ratio according to age, sex, tumor size, extrathyroidal extension (ETE), and lymph node metastasis (LNM) status, and 3,238 patients were assigned to each group. Kaplan-Meier curves, log-rank test and Cox proportional hazards regression analysis were performed. RESULTS: The follow-up period was 10.7 ± 4.2 years. Clinicopathological variables between two groups were similar except for all-cause ( p <0.001) and total cancer death ( p =0.001).","source_id":"source_2","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","year":2025,"doi":"10.1038/s41467-025-58721-6","url":"https://doi.org/10.1038/s41467-025-58721-6","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Observational and experimental evidence suggests that vitamin D plays a role in type 2 diabetes (T2D). However, prior randomized supplementation trials are limited to high-risk patients with prediabetes. Here we aim to evaluate whether vitamin D supplementation reduces risk of T2D in a general population of older US adults. The study design is an ancillary analysis (VITAL-T2D) of The Vitamin D and Omega-3 Trial (VITAL), a completed randomized, double-blind, placebo-controlled 2 × 2 trial of daily vitamin D 3 (cholecalciferol; 2000 IU/day) and omega-3 fatty acids (1 g/day) for the primary prevention of cancer and cardiovascular disease. We also conducted a systematic review and meta-analysis of vitamin D trial (≥1000 IU/d cholecalciferol) vs. placebo and T2D risk. We analyzed 22,220 adults with mean age 67.2 years (SD = 7.1) without T2D at enrollment (2011 to 2014), randomized to vitamin D 3 or placebo. Mean body mass index (BMI) was 27.5 kg/m 2 (SD = 5.3), with 51% female and 17% Black race/ethnicity. A subcohort (n = 911) attended in-person visits at baseline and 2 years for glycemic trait analyses. Our meta-analysis included 3 additional trials (5205 participants; 936 T2D cases).","source_id":"source_3","support_kind":"candidate_source_row"},{"study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","year":2022,"doi":"10.1002/jcsm.12976","url":"https://doi.org/10.1002/jcsm.12976","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis.","source_id":"source_4","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","year":2026,"doi":"10.1136/bmj-2025-087438","url":"https://doi.org/10.1136/bmj-2025-087438","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: To evaluate whether vitamin D supplementation improves live birth rates in women with polycystic ovary syndrome undergoing in vitro fertilisation. DESIGN: Multicentre, double blind, placebo controlled, randomised clinical trial. SETTING: 24 fertility centres in China. PARTICIPANTS: 876 participants with polycystic ovary syndrome undergoing in vitro fertilisation. INTERVENTIONS: Participants were randomised (1:1) to receive vitamin D 4000 IU/day or placebo before in vitro fertilisation for up to 90 days until the trigger day. MAIN OUTCOMES MEASURES: The primary outcome was live birth after the first embryo transfer. Secondary outcomes included serum 25-hydroxyvitamin D (25-OHD) levels on trigger day, pregnancy outcomes, fertility outcomes, and adverse events including severe ovarian hyperstimulation syndrome. RESULTS: Of 876 participants randomised, 865 were included in the modified intention-to-treat analysis, with 435 in the vitamin D group and 430 in the placebo group. Baseline mean serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively.","source_id":"source_5","support_kind":"candidate_source_row"}]},{"claim_id":"claim_20","claim":"Quantitative findings across these studies were predominantly null or equivocal. Effect sizes for glycemic and body composition outcomes in Miller 2021 were not reported in extractable numeric form, limiting direct cross-study comparison. Collectively, the point estimates and significance levels across these four studies do not support a robust cardiometabolic benefit of supplementation in the populations studied.","citation_support":[],"candidate_sources":[{"study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","year":2023,"doi":"10.1007/s00394-022-03038-z","url":"https://doi.org/10.1007/s00394-022-03038-z","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m 2 ) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D 3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.","source_id":"source_1","support_kind":"candidate_source_row"},{"study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","year":2023,"doi":"10.3389/fendo.2023.1163671","url":"https://doi.org/10.3389/fendo.2023.1163671","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: Benefits of vitamin D in various cancers have been reported, but its effects on differentiated thyroid cancer (DTC) have not been established. We aimed to analyze the effect of vitamin D supplementation on the prognosis of DTC. METHODS: A retrospective observational cohort study was conducted on 9,739 DTC patients who underwent thyroidectomy from January 1997 to December 2016. Mortality was classified as all-cause, cancer-related, or thyroid cancer-related. Patients were divided into the \"VD group\" (supplemented with vitamin D) and the \"control group\" (without vitamin D supplementation). Propensity score matching was performed in a 1:1 ratio according to age, sex, tumor size, extrathyroidal extension (ETE), and lymph node metastasis (LNM) status, and 3,238 patients were assigned to each group. Kaplan-Meier curves, log-rank test and Cox proportional hazards regression analysis were performed. RESULTS: The follow-up period was 10.7 ± 4.2 years. Clinicopathological variables between two groups were similar except for all-cause ( p <0.001) and total cancer death ( p =0.001).","source_id":"source_2","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","year":2025,"doi":"10.1038/s41467-025-58721-6","url":"https://doi.org/10.1038/s41467-025-58721-6","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Observational and experimental evidence suggests that vitamin D plays a role in type 2 diabetes (T2D). However, prior randomized supplementation trials are limited to high-risk patients with prediabetes. Here we aim to evaluate whether vitamin D supplementation reduces risk of T2D in a general population of older US adults. The study design is an ancillary analysis (VITAL-T2D) of The Vitamin D and Omega-3 Trial (VITAL), a completed randomized, double-blind, placebo-controlled 2 × 2 trial of daily vitamin D 3 (cholecalciferol; 2000 IU/day) and omega-3 fatty acids (1 g/day) for the primary prevention of cancer and cardiovascular disease. We also conducted a systematic review and meta-analysis of vitamin D trial (≥1000 IU/d cholecalciferol) vs. placebo and T2D risk. We analyzed 22,220 adults with mean age 67.2 years (SD = 7.1) without T2D at enrollment (2011 to 2014), randomized to vitamin D 3 or placebo. Mean body mass index (BMI) was 27.5 kg/m 2 (SD = 5.3), with 51% female and 17% Black race/ethnicity. A subcohort (n = 911) attended in-person visits at baseline and 2 years for glycemic trait analyses. Our meta-analysis included 3 additional trials (5205 participants; 936 T2D cases).","source_id":"source_3","support_kind":"candidate_source_row"},{"study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","year":2022,"doi":"10.1002/jcsm.12976","url":"https://doi.org/10.1002/jcsm.12976","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis.","source_id":"source_4","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","year":2026,"doi":"10.1136/bmj-2025-087438","url":"https://doi.org/10.1136/bmj-2025-087438","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: To evaluate whether vitamin D supplementation improves live birth rates in women with polycystic ovary syndrome undergoing in vitro fertilisation. DESIGN: Multicentre, double blind, placebo controlled, randomised clinical trial. SETTING: 24 fertility centres in China. PARTICIPANTS: 876 participants with polycystic ovary syndrome undergoing in vitro fertilisation. INTERVENTIONS: Participants were randomised (1:1) to receive vitamin D 4000 IU/day or placebo before in vitro fertilisation for up to 90 days until the trigger day. MAIN OUTCOMES MEASURES: The primary outcome was live birth after the first embryo transfer. Secondary outcomes included serum 25-hydroxyvitamin D (25-OHD) levels on trigger day, pregnancy outcomes, fertility outcomes, and adverse events including severe ovarian hyperstimulation syndrome. RESULTS: Of 876 participants randomised, 865 were included in the modified intention-to-treat analysis, with 435 in the vitamin D group and 430 in the placebo group. Baseline mean serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively.","source_id":"source_5","support_kind":"candidate_source_row"}]},{"claim_id":"claim_21","claim":"Mechanistically, vitamin D is hypothesized to influence cardiometabolic risk through effects on insulin sensitivity, inflammatory pathways, and adipocyte differentiation. Miller 2021 tested this pathway by combining vitamin D with whey protein and resistance training, targeting both glycemic control and cardiometabolic risk factors directly. Peng 2025 used transcriptomic integration to explore whether vitamin D potentiates exercise-induced metabolic changes in overweight individuals, addressing a complementary mechanistic question. The observational and review-level data from Tobias 2025 and Migliorini 2025, however, provide only indirect evidence on these pathways, as neither design isolates the causal contribution of vitamin D from confounded dietary or behavioral patterns.","citation_support":[],"candidate_sources":[{"study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","year":2023,"doi":"10.1007/s00394-022-03038-z","url":"https://doi.org/10.1007/s00394-022-03038-z","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m 2 ) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D 3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.","source_id":"source_1","support_kind":"candidate_source_row"},{"study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","year":2023,"doi":"10.3389/fendo.2023.1163671","url":"https://doi.org/10.3389/fendo.2023.1163671","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: Benefits of vitamin D in various cancers have been reported, but its effects on differentiated thyroid cancer (DTC) have not been established. We aimed to analyze the effect of vitamin D supplementation on the prognosis of DTC. METHODS: A retrospective observational cohort study was conducted on 9,739 DTC patients who underwent thyroidectomy from January 1997 to December 2016. Mortality was classified as all-cause, cancer-related, or thyroid cancer-related. Patients were divided into the \"VD group\" (supplemented with vitamin D) and the \"control group\" (without vitamin D supplementation). Propensity score matching was performed in a 1:1 ratio according to age, sex, tumor size, extrathyroidal extension (ETE), and lymph node metastasis (LNM) status, and 3,238 patients were assigned to each group. Kaplan-Meier curves, log-rank test and Cox proportional hazards regression analysis were performed. RESULTS: The follow-up period was 10.7 ± 4.2 years. Clinicopathological variables between two groups were similar except for all-cause ( p <0.001) and total cancer death ( p =0.001).","source_id":"source_2","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","year":2025,"doi":"10.1038/s41467-025-58721-6","url":"https://doi.org/10.1038/s41467-025-58721-6","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Observational and experimental evidence suggests that vitamin D plays a role in type 2 diabetes (T2D). However, prior randomized supplementation trials are limited to high-risk patients with prediabetes. Here we aim to evaluate whether vitamin D supplementation reduces risk of T2D in a general population of older US adults. The study design is an ancillary analysis (VITAL-T2D) of The Vitamin D and Omega-3 Trial (VITAL), a completed randomized, double-blind, placebo-controlled 2 × 2 trial of daily vitamin D 3 (cholecalciferol; 2000 IU/day) and omega-3 fatty acids (1 g/day) for the primary prevention of cancer and cardiovascular disease. We also conducted a systematic review and meta-analysis of vitamin D trial (≥1000 IU/d cholecalciferol) vs. placebo and T2D risk. We analyzed 22,220 adults with mean age 67.2 years (SD = 7.1) without T2D at enrollment (2011 to 2014), randomized to vitamin D 3 or placebo. Mean body mass index (BMI) was 27.5 kg/m 2 (SD = 5.3), with 51% female and 17% Black race/ethnicity. A subcohort (n = 911) attended in-person visits at baseline and 2 years for glycemic trait analyses. Our meta-analysis included 3 additional trials (5205 participants; 936 T2D cases).","source_id":"source_3","support_kind":"candidate_source_row"},{"study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","year":2022,"doi":"10.1002/jcsm.12976","url":"https://doi.org/10.1002/jcsm.12976","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis.","source_id":"source_4","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","year":2026,"doi":"10.1136/bmj-2025-087438","url":"https://doi.org/10.1136/bmj-2025-087438","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: To evaluate whether vitamin D supplementation improves live birth rates in women with polycystic ovary syndrome undergoing in vitro fertilisation. DESIGN: Multicentre, double blind, placebo controlled, randomised clinical trial. SETTING: 24 fertility centres in China. PARTICIPANTS: 876 participants with polycystic ovary syndrome undergoing in vitro fertilisation. INTERVENTIONS: Participants were randomised (1:1) to receive vitamin D 4000 IU/day or placebo before in vitro fertilisation for up to 90 days until the trigger day. MAIN OUTCOMES MEASURES: The primary outcome was live birth after the first embryo transfer. Secondary outcomes included serum 25-hydroxyvitamin D (25-OHD) levels on trigger day, pregnancy outcomes, fertility outcomes, and adverse events including severe ovarian hyperstimulation syndrome. RESULTS: Of 876 participants randomised, 865 were included in the modified intention-to-treat analysis, with 435 in the vitamin D group and 430 in the placebo group. Baseline mean serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively.","source_id":"source_5","support_kind":"candidate_source_row"}]},{"claim_id":"claim_22","claim":"Within the corpus, the direction of evidence shows notable tension. Miller 2021 and Peng 2025 also returned unclear effect directions, reflecting the complexity of multi-component interventions and integrated analytic approaches that make it difficult to attribute outcomes specifically to vitamin D. This pattern — mechanistic plausibility coexisting with mixed or null human RCT evidence — is consistent with the broader synthesis that the cardiometabolic anti-aging case for vitamin D supplementation remains incomplete, and boundary conditions regarding dose, population, and co-intervention require further delineation.","citation_support":[],"candidate_sources":[{"study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","year":2023,"doi":"10.1007/s00394-022-03038-z","url":"https://doi.org/10.1007/s00394-022-03038-z","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m 2 ) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D 3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.","source_id":"source_1","support_kind":"candidate_source_row"},{"study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","year":2023,"doi":"10.3389/fendo.2023.1163671","url":"https://doi.org/10.3389/fendo.2023.1163671","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: Benefits of vitamin D in various cancers have been reported, but its effects on differentiated thyroid cancer (DTC) have not been established. We aimed to analyze the effect of vitamin D supplementation on the prognosis of DTC. METHODS: A retrospective observational cohort study was conducted on 9,739 DTC patients who underwent thyroidectomy from January 1997 to December 2016. Mortality was classified as all-cause, cancer-related, or thyroid cancer-related. Patients were divided into the \"VD group\" (supplemented with vitamin D) and the \"control group\" (without vitamin D supplementation). Propensity score matching was performed in a 1:1 ratio according to age, sex, tumor size, extrathyroidal extension (ETE), and lymph node metastasis (LNM) status, and 3,238 patients were assigned to each group. Kaplan-Meier curves, log-rank test and Cox proportional hazards regression analysis were performed. RESULTS: The follow-up period was 10.7 ± 4.2 years. Clinicopathological variables between two groups were similar except for all-cause ( p <0.001) and total cancer death ( p =0.001).","source_id":"source_2","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","year":2025,"doi":"10.1038/s41467-025-58721-6","url":"https://doi.org/10.1038/s41467-025-58721-6","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Observational and experimental evidence suggests that vitamin D plays a role in type 2 diabetes (T2D). However, prior randomized supplementation trials are limited to high-risk patients with prediabetes. Here we aim to evaluate whether vitamin D supplementation reduces risk of T2D in a general population of older US adults. The study design is an ancillary analysis (VITAL-T2D) of The Vitamin D and Omega-3 Trial (VITAL), a completed randomized, double-blind, placebo-controlled 2 × 2 trial of daily vitamin D 3 (cholecalciferol; 2000 IU/day) and omega-3 fatty acids (1 g/day) for the primary prevention of cancer and cardiovascular disease. We also conducted a systematic review and meta-analysis of vitamin D trial (≥1000 IU/d cholecalciferol) vs. placebo and T2D risk. We analyzed 22,220 adults with mean age 67.2 years (SD = 7.1) without T2D at enrollment (2011 to 2014), randomized to vitamin D 3 or placebo. Mean body mass index (BMI) was 27.5 kg/m 2 (SD = 5.3), with 51% female and 17% Black race/ethnicity. A subcohort (n = 911) attended in-person visits at baseline and 2 years for glycemic trait analyses. Our meta-analysis included 3 additional trials (5205 participants; 936 T2D cases).","source_id":"source_3","support_kind":"candidate_source_row"},{"study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","year":2022,"doi":"10.1002/jcsm.12976","url":"https://doi.org/10.1002/jcsm.12976","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis.","source_id":"source_4","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","year":2026,"doi":"10.1136/bmj-2025-087438","url":"https://doi.org/10.1136/bmj-2025-087438","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: To evaluate whether vitamin D supplementation improves live birth rates in women with polycystic ovary syndrome undergoing in vitro fertilisation. DESIGN: Multicentre, double blind, placebo controlled, randomised clinical trial. SETTING: 24 fertility centres in China. PARTICIPANTS: 876 participants with polycystic ovary syndrome undergoing in vitro fertilisation. INTERVENTIONS: Participants were randomised (1:1) to receive vitamin D 4000 IU/day or placebo before in vitro fertilisation for up to 90 days until the trigger day. MAIN OUTCOMES MEASURES: The primary outcome was live birth after the first embryo transfer. Secondary outcomes included serum 25-hydroxyvitamin D (25-OHD) levels on trigger day, pregnancy outcomes, fertility outcomes, and adverse events including severe ovarian hyperstimulation syndrome. RESULTS: Of 876 participants randomised, 865 were included in the modified intention-to-treat analysis, with 435 in the vitamin D group and 430 in the placebo group. Baseline mean serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively.","source_id":"source_5","support_kind":"candidate_source_row"}]},{"claim_id":"claim_23","claim":"The synthesized evidence base for vitamin D supplementation on contextual outcomes encompasses systematic reviews and meta-analyses addressing distinct clinical populations, including community-dwelling older adults at risk for sarcopenia, patients with systemic lupus erythematosus (SLE), and women with polycystic ovary syndrome (PCOS). Prokopidis 2022 conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) evaluating vitamin D monotherapy versus placebo on indices of sarcopenia in older adults. In parallel, Kababi 2025 synthesized twelve studies reporting positive associations between vitamin D supplementation and reduced disease activity in SLE, while Jaafar 2026 reviewed observational data indicating a high prevalence of vitamin D deficiency in women with PCOS. Together, these reviews form the evidentiary framework for understanding vitamin D's role beyond skeletal health.","citation_support":[],"candidate_sources":[{"study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","year":2023,"doi":"10.1007/s00394-022-03038-z","url":"https://doi.org/10.1007/s00394-022-03038-z","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m 2 ) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D 3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.","source_id":"source_1","support_kind":"candidate_source_row"},{"study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","year":2023,"doi":"10.3389/fendo.2023.1163671","url":"https://doi.org/10.3389/fendo.2023.1163671","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: Benefits of vitamin D in various cancers have been reported, but its effects on differentiated thyroid cancer (DTC) have not been established. We aimed to analyze the effect of vitamin D supplementation on the prognosis of DTC. METHODS: A retrospective observational cohort study was conducted on 9,739 DTC patients who underwent thyroidectomy from January 1997 to December 2016. Mortality was classified as all-cause, cancer-related, or thyroid cancer-related. Patients were divided into the \"VD group\" (supplemented with vitamin D) and the \"control group\" (without vitamin D supplementation). Propensity score matching was performed in a 1:1 ratio according to age, sex, tumor size, extrathyroidal extension (ETE), and lymph node metastasis (LNM) status, and 3,238 patients were assigned to each group. Kaplan-Meier curves, log-rank test and Cox proportional hazards regression analysis were performed. RESULTS: The follow-up period was 10.7 ± 4.2 years. Clinicopathological variables between two groups were similar except for all-cause ( p <0.001) and total cancer death ( p =0.001).","source_id":"source_2","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","year":2025,"doi":"10.1038/s41467-025-58721-6","url":"https://doi.org/10.1038/s41467-025-58721-6","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Observational and experimental evidence suggests that vitamin D plays a role in type 2 diabetes (T2D). However, prior randomized supplementation trials are limited to high-risk patients with prediabetes. Here we aim to evaluate whether vitamin D supplementation reduces risk of T2D in a general population of older US adults. The study design is an ancillary analysis (VITAL-T2D) of The Vitamin D and Omega-3 Trial (VITAL), a completed randomized, double-blind, placebo-controlled 2 × 2 trial of daily vitamin D 3 (cholecalciferol; 2000 IU/day) and omega-3 fatty acids (1 g/day) for the primary prevention of cancer and cardiovascular disease. We also conducted a systematic review and meta-analysis of vitamin D trial (≥1000 IU/d cholecalciferol) vs. placebo and T2D risk. We analyzed 22,220 adults with mean age 67.2 years (SD = 7.1) without T2D at enrollment (2011 to 2014), randomized to vitamin D 3 or placebo. Mean body mass index (BMI) was 27.5 kg/m 2 (SD = 5.3), with 51% female and 17% Black race/ethnicity. A subcohort (n = 911) attended in-person visits at baseline and 2 years for glycemic trait analyses. Our meta-analysis included 3 additional trials (5205 participants; 936 T2D cases).","source_id":"source_3","support_kind":"candidate_source_row"},{"study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","year":2022,"doi":"10.1002/jcsm.12976","url":"https://doi.org/10.1002/jcsm.12976","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis.","source_id":"source_4","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","year":2026,"doi":"10.1136/bmj-2025-087438","url":"https://doi.org/10.1136/bmj-2025-087438","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: To evaluate whether vitamin D supplementation improves live birth rates in women with polycystic ovary syndrome undergoing in vitro fertilisation. DESIGN: Multicentre, double blind, placebo controlled, randomised clinical trial. SETTING: 24 fertility centres in China. PARTICIPANTS: 876 participants with polycystic ovary syndrome undergoing in vitro fertilisation. INTERVENTIONS: Participants were randomised (1:1) to receive vitamin D 4000 IU/day or placebo before in vitro fertilisation for up to 90 days until the trigger day. MAIN OUTCOMES MEASURES: The primary outcome was live birth after the first embryo transfer. Secondary outcomes included serum 25-hydroxyvitamin D (25-OHD) levels on trigger day, pregnancy outcomes, fertility outcomes, and adverse events including severe ovarian hyperstimulation syndrome. RESULTS: Of 876 participants randomised, 865 were included in the modified intention-to-treat analysis, with 435 in the vitamin D group and 430 in the placebo group. Baseline mean serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively.","source_id":"source_5","support_kind":"candidate_source_row"}]},{"claim_id":"claim_24","claim":"Quantitative findings from the sarcopenia-focused review by Prokopidis 2022 present a largely null profile for vitamin D monotherapy.","citation_support":[],"candidate_sources":[{"study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","year":2023,"doi":"10.1007/s00394-022-03038-z","url":"https://doi.org/10.1007/s00394-022-03038-z","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m 2 ) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D 3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.","source_id":"source_1","support_kind":"candidate_source_row"},{"study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","year":2023,"doi":"10.3389/fendo.2023.1163671","url":"https://doi.org/10.3389/fendo.2023.1163671","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: Benefits of vitamin D in various cancers have been reported, but its effects on differentiated thyroid cancer (DTC) have not been established. We aimed to analyze the effect of vitamin D supplementation on the prognosis of DTC. METHODS: A retrospective observational cohort study was conducted on 9,739 DTC patients who underwent thyroidectomy from January 1997 to December 2016. Mortality was classified as all-cause, cancer-related, or thyroid cancer-related. Patients were divided into the \"VD group\" (supplemented with vitamin D) and the \"control group\" (without vitamin D supplementation). Propensity score matching was performed in a 1:1 ratio according to age, sex, tumor size, extrathyroidal extension (ETE), and lymph node metastasis (LNM) status, and 3,238 patients were assigned to each group. Kaplan-Meier curves, log-rank test and Cox proportional hazards regression analysis were performed. RESULTS: The follow-up period was 10.7 ± 4.2 years. Clinicopathological variables between two groups were similar except for all-cause ( p <0.001) and total cancer death ( p =0.001).","source_id":"source_2","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","year":2025,"doi":"10.1038/s41467-025-58721-6","url":"https://doi.org/10.1038/s41467-025-58721-6","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Observational and experimental evidence suggests that vitamin D plays a role in type 2 diabetes (T2D). However, prior randomized supplementation trials are limited to high-risk patients with prediabetes. Here we aim to evaluate whether vitamin D supplementation reduces risk of T2D in a general population of older US adults. The study design is an ancillary analysis (VITAL-T2D) of The Vitamin D and Omega-3 Trial (VITAL), a completed randomized, double-blind, placebo-controlled 2 × 2 trial of daily vitamin D 3 (cholecalciferol; 2000 IU/day) and omega-3 fatty acids (1 g/day) for the primary prevention of cancer and cardiovascular disease. We also conducted a systematic review and meta-analysis of vitamin D trial (≥1000 IU/d cholecalciferol) vs. placebo and T2D risk. We analyzed 22,220 adults with mean age 67.2 years (SD = 7.1) without T2D at enrollment (2011 to 2014), randomized to vitamin D 3 or placebo. Mean body mass index (BMI) was 27.5 kg/m 2 (SD = 5.3), with 51% female and 17% Black race/ethnicity. A subcohort (n = 911) attended in-person visits at baseline and 2 years for glycemic trait analyses. Our meta-analysis included 3 additional trials (5205 participants; 936 T2D cases).","source_id":"source_3","support_kind":"candidate_source_row"},{"study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","year":2022,"doi":"10.1002/jcsm.12976","url":"https://doi.org/10.1002/jcsm.12976","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis.","source_id":"source_4","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","year":2026,"doi":"10.1136/bmj-2025-087438","url":"https://doi.org/10.1136/bmj-2025-087438","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: To evaluate whether vitamin D supplementation improves live birth rates in women with polycystic ovary syndrome undergoing in vitro fertilisation. DESIGN: Multicentre, double blind, placebo controlled, randomised clinical trial. SETTING: 24 fertility centres in China. PARTICIPANTS: 876 participants with polycystic ovary syndrome undergoing in vitro fertilisation. INTERVENTIONS: Participants were randomised (1:1) to receive vitamin D 4000 IU/day or placebo before in vitro fertilisation for up to 90 days until the trigger day. MAIN OUTCOMES MEASURES: The primary outcome was live birth after the first embryo transfer. Secondary outcomes included serum 25-hydroxyvitamin D (25-OHD) levels on trigger day, pregnancy outcomes, fertility outcomes, and adverse events including severe ovarian hyperstimulation syndrome. RESULTS: Of 876 participants randomised, 865 were included in the modified intention-to-treat analysis, with 435 in the vitamin D group and 430 in the placebo group. Baseline mean serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively.","source_id":"source_5","support_kind":"candidate_source_row"}]},{"claim_id":"claim_25","claim":"Mechanistically, the disparity between null findings in sarcopenia trials and positive signals in autoimmune and endocrine contexts may reflect differences in disease-specific pathways. Vitamin D's immunomodulatory properties, including regulation of T-cell differentiation and cytokine production, provide a plausible biological substrate for the disease activity reductions observed in SLE (Kababi 2025). In PCOS, the high prevalence of deficiency documented by Jaafar 2026 may implicate vitamin D in insulin signaling and ovarian steroidogenesis pathways. Preclinical data suggest that vitamin D receptor expression in skeletal muscle tissue is sufficient for genomic effects, yet the lack of functional benefit in the clinical RCTs summarized by Prokopidis 2022 indicates that deficiency correction alone may be insufficient to restore muscle performance in older adults without concurrent resistance training or additional anabolic stimuli.","citation_support":[],"candidate_sources":[{"study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","year":2023,"doi":"10.1007/s00394-022-03038-z","url":"https://doi.org/10.1007/s00394-022-03038-z","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m 2 ) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D 3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.","source_id":"source_1","support_kind":"candidate_source_row"},{"study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","year":2023,"doi":"10.3389/fendo.2023.1163671","url":"https://doi.org/10.3389/fendo.2023.1163671","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: Benefits of vitamin D in various cancers have been reported, but its effects on differentiated thyroid cancer (DTC) have not been established. We aimed to analyze the effect of vitamin D supplementation on the prognosis of DTC. METHODS: A retrospective observational cohort study was conducted on 9,739 DTC patients who underwent thyroidectomy from January 1997 to December 2016. Mortality was classified as all-cause, cancer-related, or thyroid cancer-related. Patients were divided into the \"VD group\" (supplemented with vitamin D) and the \"control group\" (without vitamin D supplementation). Propensity score matching was performed in a 1:1 ratio according to age, sex, tumor size, extrathyroidal extension (ETE), and lymph node metastasis (LNM) status, and 3,238 patients were assigned to each group. Kaplan-Meier curves, log-rank test and Cox proportional hazards regression analysis were performed. RESULTS: The follow-up period was 10.7 ± 4.2 years. Clinicopathological variables between two groups were similar except for all-cause ( p <0.001) and total cancer death ( p =0.001).","source_id":"source_2","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","year":2025,"doi":"10.1038/s41467-025-58721-6","url":"https://doi.org/10.1038/s41467-025-58721-6","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Observational and experimental evidence suggests that vitamin D plays a role in type 2 diabetes (T2D). However, prior randomized supplementation trials are limited to high-risk patients with prediabetes. Here we aim to evaluate whether vitamin D supplementation reduces risk of T2D in a general population of older US adults. The study design is an ancillary analysis (VITAL-T2D) of The Vitamin D and Omega-3 Trial (VITAL), a completed randomized, double-blind, placebo-controlled 2 × 2 trial of daily vitamin D 3 (cholecalciferol; 2000 IU/day) and omega-3 fatty acids (1 g/day) for the primary prevention of cancer and cardiovascular disease. We also conducted a systematic review and meta-analysis of vitamin D trial (≥1000 IU/d cholecalciferol) vs. placebo and T2D risk. We analyzed 22,220 adults with mean age 67.2 years (SD = 7.1) without T2D at enrollment (2011 to 2014), randomized to vitamin D 3 or placebo. Mean body mass index (BMI) was 27.5 kg/m 2 (SD = 5.3), with 51% female and 17% Black race/ethnicity. A subcohort (n = 911) attended in-person visits at baseline and 2 years for glycemic trait analyses. Our meta-analysis included 3 additional trials (5205 participants; 936 T2D cases).","source_id":"source_3","support_kind":"candidate_source_row"},{"study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","year":2022,"doi":"10.1002/jcsm.12976","url":"https://doi.org/10.1002/jcsm.12976","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis.","source_id":"source_4","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","year":2026,"doi":"10.1136/bmj-2025-087438","url":"https://doi.org/10.1136/bmj-2025-087438","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: To evaluate whether vitamin D supplementation improves live birth rates in women with polycystic ovary syndrome undergoing in vitro fertilisation. DESIGN: Multicentre, double blind, placebo controlled, randomised clinical trial. SETTING: 24 fertility centres in China. PARTICIPANTS: 876 participants with polycystic ovary syndrome undergoing in vitro fertilisation. INTERVENTIONS: Participants were randomised (1:1) to receive vitamin D 4000 IU/day or placebo before in vitro fertilisation for up to 90 days until the trigger day. MAIN OUTCOMES MEASURES: The primary outcome was live birth after the first embryo transfer. Secondary outcomes included serum 25-hydroxyvitamin D (25-OHD) levels on trigger day, pregnancy outcomes, fertility outcomes, and adverse events including severe ovarian hyperstimulation syndrome. RESULTS: Of 876 participants randomised, 865 were included in the modified intention-to-treat analysis, with 435 in the vitamin D group and 430 in the placebo group. Baseline mean serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively.","source_id":"source_5","support_kind":"candidate_source_row"}]},{"claim_id":"claim_26","claim":"Within the curated corpus, a clear tension emerges between the null-to-minimal effects on sarcopenia indices reported by Prokopidis 2022 and the positive associations for autoimmune and endocrine outcomes documented by Kababi 2025 and Jaafar 2026. This discordance underscores the context-dependent nature of vitamin D's clinical utility: immunomodulatory and endocrine endpoints may be more responsive to supplementation than structural musculoskeletal outcomes, and the boundary conditions governing these differential responses require further delineation through targeted mechanistic and clinical investigation.","citation_support":[],"candidate_sources":[{"study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","year":2023,"doi":"10.1007/s00394-022-03038-z","url":"https://doi.org/10.1007/s00394-022-03038-z","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m 2 ) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D 3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.","source_id":"source_1","support_kind":"candidate_source_row"},{"study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","year":2023,"doi":"10.3389/fendo.2023.1163671","url":"https://doi.org/10.3389/fendo.2023.1163671","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: Benefits of vitamin D in various cancers have been reported, but its effects on differentiated thyroid cancer (DTC) have not been established. We aimed to analyze the effect of vitamin D supplementation on the prognosis of DTC. METHODS: A retrospective observational cohort study was conducted on 9,739 DTC patients who underwent thyroidectomy from January 1997 to December 2016. Mortality was classified as all-cause, cancer-related, or thyroid cancer-related. Patients were divided into the \"VD group\" (supplemented with vitamin D) and the \"control group\" (without vitamin D supplementation). Propensity score matching was performed in a 1:1 ratio according to age, sex, tumor size, extrathyroidal extension (ETE), and lymph node metastasis (LNM) status, and 3,238 patients were assigned to each group. Kaplan-Meier curves, log-rank test and Cox proportional hazards regression analysis were performed. RESULTS: The follow-up period was 10.7 ± 4.2 years. Clinicopathological variables between two groups were similar except for all-cause ( p <0.001) and total cancer death ( p =0.001).","source_id":"source_2","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","year":2025,"doi":"10.1038/s41467-025-58721-6","url":"https://doi.org/10.1038/s41467-025-58721-6","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Observational and experimental evidence suggests that vitamin D plays a role in type 2 diabetes (T2D). However, prior randomized supplementation trials are limited to high-risk patients with prediabetes. Here we aim to evaluate whether vitamin D supplementation reduces risk of T2D in a general population of older US adults. The study design is an ancillary analysis (VITAL-T2D) of The Vitamin D and Omega-3 Trial (VITAL), a completed randomized, double-blind, placebo-controlled 2 × 2 trial of daily vitamin D 3 (cholecalciferol; 2000 IU/day) and omega-3 fatty acids (1 g/day) for the primary prevention of cancer and cardiovascular disease. We also conducted a systematic review and meta-analysis of vitamin D trial (≥1000 IU/d cholecalciferol) vs. placebo and T2D risk. We analyzed 22,220 adults with mean age 67.2 years (SD = 7.1) without T2D at enrollment (2011 to 2014), randomized to vitamin D 3 or placebo. Mean body mass index (BMI) was 27.5 kg/m 2 (SD = 5.3), with 51% female and 17% Black race/ethnicity. A subcohort (n = 911) attended in-person visits at baseline and 2 years for glycemic trait analyses. Our meta-analysis included 3 additional trials (5205 participants; 936 T2D cases).","source_id":"source_3","support_kind":"candidate_source_row"},{"study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","year":2022,"doi":"10.1002/jcsm.12976","url":"https://doi.org/10.1002/jcsm.12976","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis.","source_id":"source_4","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","year":2026,"doi":"10.1136/bmj-2025-087438","url":"https://doi.org/10.1136/bmj-2025-087438","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: To evaluate whether vitamin D supplementation improves live birth rates in women with polycystic ovary syndrome undergoing in vitro fertilisation. DESIGN: Multicentre, double blind, placebo controlled, randomised clinical trial. SETTING: 24 fertility centres in China. PARTICIPANTS: 876 participants with polycystic ovary syndrome undergoing in vitro fertilisation. INTERVENTIONS: Participants were randomised (1:1) to receive vitamin D 4000 IU/day or placebo before in vitro fertilisation for up to 90 days until the trigger day. MAIN OUTCOMES MEASURES: The primary outcome was live birth after the first embryo transfer. Secondary outcomes included serum 25-hydroxyvitamin D (25-OHD) levels on trigger day, pregnancy outcomes, fertility outcomes, and adverse events including severe ovarian hyperstimulation syndrome. RESULTS: Of 876 participants randomised, 865 were included in the modified intention-to-treat analysis, with 435 in the vitamin D group and 430 in the placebo group. Baseline mean serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively.","source_id":"source_5","support_kind":"candidate_source_row"}]},{"claim_id":"claim_27","claim":"The evidence base for vitamin D supplementation's impact on deficiency prevalence and related metabolic markers is drawn from a heterogeneous collection of study designs.","citation_support":[],"candidate_sources":[{"study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","year":2023,"doi":"10.1007/s00394-022-03038-z","url":"https://doi.org/10.1007/s00394-022-03038-z","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m 2 ) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D 3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.","source_id":"source_1","support_kind":"candidate_source_row"},{"study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","year":2023,"doi":"10.3389/fendo.2023.1163671","url":"https://doi.org/10.3389/fendo.2023.1163671","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: Benefits of vitamin D in various cancers have been reported, but its effects on differentiated thyroid cancer (DTC) have not been established. We aimed to analyze the effect of vitamin D supplementation on the prognosis of DTC. METHODS: A retrospective observational cohort study was conducted on 9,739 DTC patients who underwent thyroidectomy from January 1997 to December 2016. Mortality was classified as all-cause, cancer-related, or thyroid cancer-related. Patients were divided into the \"VD group\" (supplemented with vitamin D) and the \"control group\" (without vitamin D supplementation). Propensity score matching was performed in a 1:1 ratio according to age, sex, tumor size, extrathyroidal extension (ETE), and lymph node metastasis (LNM) status, and 3,238 patients were assigned to each group. Kaplan-Meier curves, log-rank test and Cox proportional hazards regression analysis were performed. RESULTS: The follow-up period was 10.7 ± 4.2 years. Clinicopathological variables between two groups were similar except for all-cause ( p <0.001) and total cancer death ( p =0.001).","source_id":"source_2","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","year":2025,"doi":"10.1038/s41467-025-58721-6","url":"https://doi.org/10.1038/s41467-025-58721-6","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Observational and experimental evidence suggests that vitamin D plays a role in type 2 diabetes (T2D). However, prior randomized supplementation trials are limited to high-risk patients with prediabetes. Here we aim to evaluate whether vitamin D supplementation reduces risk of T2D in a general population of older US adults. The study design is an ancillary analysis (VITAL-T2D) of The Vitamin D and Omega-3 Trial (VITAL), a completed randomized, double-blind, placebo-controlled 2 × 2 trial of daily vitamin D 3 (cholecalciferol; 2000 IU/day) and omega-3 fatty acids (1 g/day) for the primary prevention of cancer and cardiovascular disease. We also conducted a systematic review and meta-analysis of vitamin D trial (≥1000 IU/d cholecalciferol) vs. placebo and T2D risk. We analyzed 22,220 adults with mean age 67.2 years (SD = 7.1) without T2D at enrollment (2011 to 2014), randomized to vitamin D 3 or placebo. Mean body mass index (BMI) was 27.5 kg/m 2 (SD = 5.3), with 51% female and 17% Black race/ethnicity. A subcohort (n = 911) attended in-person visits at baseline and 2 years for glycemic trait analyses. Our meta-analysis included 3 additional trials (5205 participants; 936 T2D cases).","source_id":"source_3","support_kind":"candidate_source_row"},{"study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","year":2022,"doi":"10.1002/jcsm.12976","url":"https://doi.org/10.1002/jcsm.12976","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis.","source_id":"source_4","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","year":2026,"doi":"10.1136/bmj-2025-087438","url":"https://doi.org/10.1136/bmj-2025-087438","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: To evaluate whether vitamin D supplementation improves live birth rates in women with polycystic ovary syndrome undergoing in vitro fertilisation. DESIGN: Multicentre, double blind, placebo controlled, randomised clinical trial. SETTING: 24 fertility centres in China. PARTICIPANTS: 876 participants with polycystic ovary syndrome undergoing in vitro fertilisation. INTERVENTIONS: Participants were randomised (1:1) to receive vitamin D 4000 IU/day or placebo before in vitro fertilisation for up to 90 days until the trigger day. MAIN OUTCOMES MEASURES: The primary outcome was live birth after the first embryo transfer. Secondary outcomes included serum 25-hydroxyvitamin D (25-OHD) levels on trigger day, pregnancy outcomes, fertility outcomes, and adverse events including severe ovarian hyperstimulation syndrome. RESULTS: Of 876 participants randomised, 865 were included in the modified intention-to-treat analysis, with 435 in the vitamin D group and 430 in the placebo group. Baseline mean serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively.","source_id":"source_5","support_kind":"candidate_source_row"}]},{"claim_id":"claim_28","claim":"Quantitative findings on deficiency correction are divergent across populations and endpoints. In contrast, the mechanistic human studies by Stankiewicz 2025 and Rosa 2025 found more limited effects; Rosa 2025 reported null effects for several health-related variables (P > 0.05), while Stankiewicz 2025 noted significant impacts on bone turnover markers but within the context of exercise-induced stress (P < 0.01).","citation_support":[],"candidate_sources":[{"study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","year":2023,"doi":"10.1007/s00394-022-03038-z","url":"https://doi.org/10.1007/s00394-022-03038-z","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m 2 ) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D 3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.","source_id":"source_1","support_kind":"candidate_source_row"},{"study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","year":2023,"doi":"10.3389/fendo.2023.1163671","url":"https://doi.org/10.3389/fendo.2023.1163671","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: Benefits of vitamin D in various cancers have been reported, but its effects on differentiated thyroid cancer (DTC) have not been established. We aimed to analyze the effect of vitamin D supplementation on the prognosis of DTC. METHODS: A retrospective observational cohort study was conducted on 9,739 DTC patients who underwent thyroidectomy from January 1997 to December 2016. Mortality was classified as all-cause, cancer-related, or thyroid cancer-related. Patients were divided into the \"VD group\" (supplemented with vitamin D) and the \"control group\" (without vitamin D supplementation). Propensity score matching was performed in a 1:1 ratio according to age, sex, tumor size, extrathyroidal extension (ETE), and lymph node metastasis (LNM) status, and 3,238 patients were assigned to each group. Kaplan-Meier curves, log-rank test and Cox proportional hazards regression analysis were performed. RESULTS: The follow-up period was 10.7 ± 4.2 years. Clinicopathological variables between two groups were similar except for all-cause ( p <0.001) and total cancer death ( p =0.001).","source_id":"source_2","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","year":2025,"doi":"10.1038/s41467-025-58721-6","url":"https://doi.org/10.1038/s41467-025-58721-6","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Observational and experimental evidence suggests that vitamin D plays a role in type 2 diabetes (T2D). However, prior randomized supplementation trials are limited to high-risk patients with prediabetes. Here we aim to evaluate whether vitamin D supplementation reduces risk of T2D in a general population of older US adults. The study design is an ancillary analysis (VITAL-T2D) of The Vitamin D and Omega-3 Trial (VITAL), a completed randomized, double-blind, placebo-controlled 2 × 2 trial of daily vitamin D 3 (cholecalciferol; 2000 IU/day) and omega-3 fatty acids (1 g/day) for the primary prevention of cancer and cardiovascular disease. We also conducted a systematic review and meta-analysis of vitamin D trial (≥1000 IU/d cholecalciferol) vs. placebo and T2D risk. We analyzed 22,220 adults with mean age 67.2 years (SD = 7.1) without T2D at enrollment (2011 to 2014), randomized to vitamin D 3 or placebo. Mean body mass index (BMI) was 27.5 kg/m 2 (SD = 5.3), with 51% female and 17% Black race/ethnicity. A subcohort (n = 911) attended in-person visits at baseline and 2 years for glycemic trait analyses. Our meta-analysis included 3 additional trials (5205 participants; 936 T2D cases).","source_id":"source_3","support_kind":"candidate_source_row"},{"study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","year":2022,"doi":"10.1002/jcsm.12976","url":"https://doi.org/10.1002/jcsm.12976","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis.","source_id":"source_4","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","year":2026,"doi":"10.1136/bmj-2025-087438","url":"https://doi.org/10.1136/bmj-2025-087438","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: To evaluate whether vitamin D supplementation improves live birth rates in women with polycystic ovary syndrome undergoing in vitro fertilisation. DESIGN: Multicentre, double blind, placebo controlled, randomised clinical trial. SETTING: 24 fertility centres in China. PARTICIPANTS: 876 participants with polycystic ovary syndrome undergoing in vitro fertilisation. INTERVENTIONS: Participants were randomised (1:1) to receive vitamin D 4000 IU/day or placebo before in vitro fertilisation for up to 90 days until the trigger day. MAIN OUTCOMES MEASURES: The primary outcome was live birth after the first embryo transfer. Secondary outcomes included serum 25-hydroxyvitamin D (25-OHD) levels on trigger day, pregnancy outcomes, fertility outcomes, and adverse events including severe ovarian hyperstimulation syndrome. RESULTS: Of 876 participants randomised, 865 were included in the modified intention-to-treat analysis, with 435 in the vitamin D group and 430 in the placebo group. Baseline mean serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively.","source_id":"source_5","support_kind":"candidate_source_row"}]},{"claim_id":"claim_29","claim":"Mechanistically, the efficacy of supplementation appears linked to baseline status and co-interventions. The clear biochemical changes observed by Stankiewicz 2025 (P < 0.01) and Rosa 2025 (P = 0.03) in exercise contexts suggest that physical stress may modulate the biochemical response to supplementation.","citation_support":[],"candidate_sources":[{"study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","year":2023,"doi":"10.1007/s00394-022-03038-z","url":"https://doi.org/10.1007/s00394-022-03038-z","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m 2 ) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D 3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.","source_id":"source_1","support_kind":"candidate_source_row"},{"study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","year":2023,"doi":"10.3389/fendo.2023.1163671","url":"https://doi.org/10.3389/fendo.2023.1163671","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: Benefits of vitamin D in various cancers have been reported, but its effects on differentiated thyroid cancer (DTC) have not been established. We aimed to analyze the effect of vitamin D supplementation on the prognosis of DTC. METHODS: A retrospective observational cohort study was conducted on 9,739 DTC patients who underwent thyroidectomy from January 1997 to December 2016. Mortality was classified as all-cause, cancer-related, or thyroid cancer-related. Patients were divided into the \"VD group\" (supplemented with vitamin D) and the \"control group\" (without vitamin D supplementation). Propensity score matching was performed in a 1:1 ratio according to age, sex, tumor size, extrathyroidal extension (ETE), and lymph node metastasis (LNM) status, and 3,238 patients were assigned to each group. Kaplan-Meier curves, log-rank test and Cox proportional hazards regression analysis were performed. RESULTS: The follow-up period was 10.7 ± 4.2 years. Clinicopathological variables between two groups were similar except for all-cause ( p <0.001) and total cancer death ( p =0.001).","source_id":"source_2","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","year":2025,"doi":"10.1038/s41467-025-58721-6","url":"https://doi.org/10.1038/s41467-025-58721-6","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Observational and experimental evidence suggests that vitamin D plays a role in type 2 diabetes (T2D). However, prior randomized supplementation trials are limited to high-risk patients with prediabetes. Here we aim to evaluate whether vitamin D supplementation reduces risk of T2D in a general population of older US adults. The study design is an ancillary analysis (VITAL-T2D) of The Vitamin D and Omega-3 Trial (VITAL), a completed randomized, double-blind, placebo-controlled 2 × 2 trial of daily vitamin D 3 (cholecalciferol; 2000 IU/day) and omega-3 fatty acids (1 g/day) for the primary prevention of cancer and cardiovascular disease. We also conducted a systematic review and meta-analysis of vitamin D trial (≥1000 IU/d cholecalciferol) vs. placebo and T2D risk. We analyzed 22,220 adults with mean age 67.2 years (SD = 7.1) without T2D at enrollment (2011 to 2014), randomized to vitamin D 3 or placebo. Mean body mass index (BMI) was 27.5 kg/m 2 (SD = 5.3), with 51% female and 17% Black race/ethnicity. A subcohort (n = 911) attended in-person visits at baseline and 2 years for glycemic trait analyses. Our meta-analysis included 3 additional trials (5205 participants; 936 T2D cases).","source_id":"source_3","support_kind":"candidate_source_row"},{"study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","year":2022,"doi":"10.1002/jcsm.12976","url":"https://doi.org/10.1002/jcsm.12976","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis.","source_id":"source_4","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","year":2026,"doi":"10.1136/bmj-2025-087438","url":"https://doi.org/10.1136/bmj-2025-087438","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: To evaluate whether vitamin D supplementation improves live birth rates in women with polycystic ovary syndrome undergoing in vitro fertilisation. DESIGN: Multicentre, double blind, placebo controlled, randomised clinical trial. SETTING: 24 fertility centres in China. PARTICIPANTS: 876 participants with polycystic ovary syndrome undergoing in vitro fertilisation. INTERVENTIONS: Participants were randomised (1:1) to receive vitamin D 4000 IU/day or placebo before in vitro fertilisation for up to 90 days until the trigger day. MAIN OUTCOMES MEASURES: The primary outcome was live birth after the first embryo transfer. Secondary outcomes included serum 25-hydroxyvitamin D (25-OHD) levels on trigger day, pregnancy outcomes, fertility outcomes, and adverse events including severe ovarian hyperstimulation syndrome. RESULTS: Of 876 participants randomised, 865 were included in the modified intention-to-treat analysis, with 435 in the vitamin D group and 430 in the placebo group. Baseline mean serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively.","source_id":"source_5","support_kind":"candidate_source_row"}]},{"claim_id":"claim_30","claim":"The evidence base for vitamin D supplementation effects on dosing and pharmacokinetics spans diverse clinical contexts, from critically ill patients to those with type 2 diabetes, osteoporosis, and polycystic ovary syndrome. Several systematic reviews and meta-analyses synthesized data from numerous randomized controlled trials, while a direct clinical RCT in overweight and obese patients with chronic low-grade inflammation examined combined supplementation. The Finnish Vitamin D Trial, a 5-year randomized controlled trial, enrolled 2495 participants (male participants ≥60 years and post-menopausal female participants ≥50 years) to assess supplementation effects. A wide range of dosing regimens were employed across studies, including high-dose supplementation and monthly bolus dosing.","citation_support":[],"candidate_sources":[{"study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","year":2023,"doi":"10.1007/s00394-022-03038-z","url":"https://doi.org/10.1007/s00394-022-03038-z","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m 2 ) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D 3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2.","source_id":"source_1","support_kind":"candidate_source_row"},{"study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","year":2023,"doi":"10.3389/fendo.2023.1163671","url":"https://doi.org/10.3389/fendo.2023.1163671","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: Benefits of vitamin D in various cancers have been reported, but its effects on differentiated thyroid cancer (DTC) have not been established. We aimed to analyze the effect of vitamin D supplementation on the prognosis of DTC. METHODS: A retrospective observational cohort study was conducted on 9,739 DTC patients who underwent thyroidectomy from January 1997 to December 2016. Mortality was classified as all-cause, cancer-related, or thyroid cancer-related. Patients were divided into the \"VD group\" (supplemented with vitamin D) and the \"control group\" (without vitamin D supplementation). Propensity score matching was performed in a 1:1 ratio according to age, sex, tumor size, extrathyroidal extension (ETE), and lymph node metastasis (LNM) status, and 3,238 patients were assigned to each group. Kaplan-Meier curves, log-rank test and Cox proportional hazards regression analysis were performed. RESULTS: The follow-up period was 10.7 ± 4.2 years. Clinicopathological variables between two groups were similar except for all-cause ( p <0.001) and total cancer death ( p =0.001).","source_id":"source_2","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","year":2025,"doi":"10.1038/s41467-025-58721-6","url":"https://doi.org/10.1038/s41467-025-58721-6","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Observational and experimental evidence suggests that vitamin D plays a role in type 2 diabetes (T2D). However, prior randomized supplementation trials are limited to high-risk patients with prediabetes. Here we aim to evaluate whether vitamin D supplementation reduces risk of T2D in a general population of older US adults. The study design is an ancillary analysis (VITAL-T2D) of The Vitamin D and Omega-3 Trial (VITAL), a completed randomized, double-blind, placebo-controlled 2 × 2 trial of daily vitamin D 3 (cholecalciferol; 2000 IU/day) and omega-3 fatty acids (1 g/day) for the primary prevention of cancer and cardiovascular disease. We also conducted a systematic review and meta-analysis of vitamin D trial (≥1000 IU/d cholecalciferol) vs. placebo and T2D risk. We analyzed 22,220 adults with mean age 67.2 years (SD = 7.1) without T2D at enrollment (2011 to 2014), randomized to vitamin D 3 or placebo. Mean body mass index (BMI) was 27.5 kg/m 2 (SD = 5.3), with 51% female and 17% Black race/ethnicity. A subcohort (n = 911) attended in-person visits at baseline and 2 years for glycemic trait analyses. Our meta-analysis included 3 additional trials (5205 participants; 936 T2D cases).","source_id":"source_3","support_kind":"candidate_source_row"},{"study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","year":2022,"doi":"10.1002/jcsm.12976","url":"https://doi.org/10.1002/jcsm.12976","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis.","source_id":"source_4","support_kind":"candidate_source_row"},{"study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","year":2026,"doi":"10.1136/bmj-2025-087438","url":"https://doi.org/10.1136/bmj-2025-087438","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: To evaluate whether vitamin D supplementation improves live birth rates in women with polycystic ovary syndrome undergoing in vitro fertilisation. DESIGN: Multicentre, double blind, placebo controlled, randomised clinical trial. SETTING: 24 fertility centres in China. PARTICIPANTS: 876 participants with polycystic ovary syndrome undergoing in vitro fertilisation. INTERVENTIONS: Participants were randomised (1:1) to receive vitamin D 4000 IU/day or placebo before in vitro fertilisation for up to 90 days until the trigger day. MAIN OUTCOMES MEASURES: The primary outcome was live birth after the first embryo transfer. Secondary outcomes included serum 25-hydroxyvitamin D (25-OHD) levels on trigger day, pregnancy outcomes, fertility outcomes, and adverse events including severe ovarian hyperstimulation syndrome. RESULTS: Of 876 participants randomised, 865 were included in the modified intention-to-treat analysis, with 435 in the vitamin D group and 430 in the placebo group. Baseline mean serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively.","source_id":"source_5","support_kind":"candidate_source_row"}]}]}},{"name":"claim_graph.json","media_type":"application/json","content":{"publication_id":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","content_hash":"sha256:ff5822aa52c93173722558f3dfb0d1d9e40fb4b104faa28b9c7d5d0eefa1e157","nodes":[{"id":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","type":"publication","title":"Research Synthesis: Vitamin D Supplementation Effects — full paper"},{"id":"claim_1","type":"claim","text":"Evidence-honesty note: 58/62 retained sources are indirect, review-level, adjacent, or mechanistic and are used only to bound interpretation. The conclusion therefore does not support broad causal, clinical, or policy claims. Vitamin D supplementation is among the most widely prescribed interventions worldwide, yet its clinical benefits beyond correcting deficiency remain contentious across cardiometabolic, musculoskeletal, immune, and longevity outcomes. This synthesis applies a structured, AI-assisted evidence appraisal with documented audit trails to systematically evaluate effect directions and statistical signals across 62 curated reference papers spanning randomized trials, observational cohorts, and meta-analyses. For immune and inflammatory markers, vitamin D supplementation in women with PCOS significantly reduced inflammatory biomarkers (P < 0.001) (Akbari 2018), yet a separate meta-analysis of obese or overweight populations reported mixed findings on co-supplementation with magnesium (Deng 2025). Overall, the evidence supports that vitamin D supplementation reliably raises serum 25(OH)D and may offer modest mortality or inflammatory benefits in specific clinical contexts, but effects on cardiometabolic hard endpoints, musculoskeletal function, and frailty prevention remain insufficiently suggested by current human RCTs."},{"id":"claim_2","type":"claim","text":"Evidence-honesty note: 58/62 retained sources are indirect, review-level, adjacent, or mechanistic and are used only to bound interpretation. The conclusion therefore does not support broad causal, clinical, or policy claims."},{"id":"claim_3","type":"claim","text":"This synthesis applies a structured, AI-assisted evidence appraisal with documented audit trails to systematically evaluate effect directions and statistical signals across 62 curated reference papers spanning randomized trials, observational cohorts, and meta-analyses."},{"id":"claim_4","type":"claim","text":"Overall, the evidence supports that vitamin D supplementation reliably raises serum 25(OH)D and may offer modest mortality or inflammatory benefits in specific clinical contexts, but effects on cardiometabolic hard endpoints, musculoskeletal function, and frailty prevention remain insufficiently suggested by current human RCTs."},{"id":"claim_5","type":"claim","text":"Interpretation below therefore separates primary clinical-trial evidence from review-level, preclinical, and other indirect evidence."},{"id":"claim_6","type":"claim","text":"Aging populations worldwide face a growing burden of chronic disease, functional decline, and reduced healthspan, creating urgent interest in interventions that might modify the trajectory of age-related deterioration. Vitamin D supplementation effects have emerged as a particularly compelling area of investigation, given that vitamin D deficiency is highly prevalent among older adults and has been associated with numerous adverse health outcomes. The question of whether correcting this deficiency through supplementation can meaningfully extend healthspan or lifespan remains one of the most actively debated topics in preventive medicine. Epidemiological studies have consistently linked low serum 25-hydroxyvitamin D levels with increased mortality, cardiovascular disease, diabetes, and cancer, yet the causal direction of these associations has been difficult to establish. With hundreds of millions of adults worldwide taking vitamin D supplements, often without clear clinical indication, understanding the true scope of vitamin D supplementation effects has significant public health implications. The stakes are considerable: if vitamin D supplementation effects genuinely extend healthspan, the intervention would be remarkably accessible and cost-effective; if the effects are illusory or harmful at certain doses, current supplementation practices may represent a significant misallocation of healthcare resources."},{"id":"claim_7","type":"claim","text":"The geroscience hypothesis proposes that targeting fundamental aging biology — rather than individual diseases one at a time — could delay or prevent multiple age-related conditions simultaneously. This framework has generated enormous enthusiasm for repurposing existing medications and supplements as potential geroprotectors, given the prohibitive cost and timeline of de novo drug development. Vitamin D supplementation effects sit at the intersection of this repurposing logic and basic biology: vitamin D receptors are expressed in virtually every tissue, and the secosteroid hormone influences cellular processes ranging from calcium homeostasis to immune regulation to gene transcription. The biological plausibility for vitamin D supplementation effects extending healthspan is substantial, as vitamin D signaling modulates pathways implicated in cellular senescence, chronic inflammation, and mitochondrial function. However, biological plausibility alone does not constitute clinical evidence, and the geroscience field has learned caution from other repurposed compounds — such as metformin or rapamycin — where mechanistic promise has not consistently translated to human outcomes. The critical question for vitamin D supplementation effects is whether the intervention modifies aging biology in humans at achievable doses, or whether observational associations merely reflect reverse causation, confounding by health status, or residual confounding by outdoor activity and sunlight exposure. Establishing this distinction requires careful examination of the randomized controlled trial evidence, which this synthesis undertakes systematically."},{"id":"claim_8","type":"claim","text":"Several unresolved questions pervade the literature on vitamin D supplementation effects, creating persistent uncertainty about clinical applicability. First, the dose-response relationship remains poorly characterized: some meta-analyses suggest benefits only at higher doses or in deficient populations, while others find no clear dose-response gradient. Second, the translation from mechanistic plausibility to clinical function is incomplete — for example, vitamin D supplementation effects on inflammatory markers such as C-reactive protein do not reliably predict improvements in hard outcomes. Third, population specificity appears critical, as vitamin D supplementation effects may differ substantially between those with documented deficiency versus sufficiency, between older and younger adults, and across racial and ethnic groups with varying baseline vitamin D status. Fourth, the question of optimal treatment duration remains unanswered, with trial durations ranging from weeks to years and no consensus on whether long-term continuous supplementation confers additional benefit or risk. Fifth, genetic polymorphisms in the vitamin D receptor may modify vitamin D supplementation effects, as suggested by recent pharmacogenomic analyses, but this evidence remains preliminary. Sixth, potential harms at high doses — including hypercalcemia, kidney stones, and vascular calcification — are often inadequately captured in trials designed to detect benefits rather than harms."},{"id":"claim_9","type":"claim","text":"Preclinical and disease-model studies provide the mechanistic substrate for the vitamin D supplementation effects hypothesis, and the corpus under review spans cell-culture, rodent, and human tissue investigations that collectively implicate vitamin D in inflammation, metabolic regulation, and cellular resilience. The mechanistic plausibility of vitamin D as a modulator of mitochondrial function and oxidative stress is further supported by a randomized controlled trial showing that vitamin D supplementation improves cognitive function through reducing oxidative stress regulated by telomere length in older adults with mild cognitive impairment (Yang 2020, 12-month RCT). Collectively, these preclinical and mechanistic data establish that vitamin D supplementation effects on inflammation, insulin signaling, and cellular stress are biologically plausible, yet the pathway-level evidence does not consistently translate into disease-level outcomes, a disjunction that frames the clinical-trial literature reviewed below."},{"id":"claim_10","type":"claim","text":"The biological rationale is treated as context rather than as clinical proof. Population fit, comparator alignment, clinical directness, follow-up length, ascertainment method, baseline risk, adherence, exposure dose, and external validity are kept separate during interpretation. The interpretation"},{"id":"claim_11","type":"claim","text":"The following fields were extracted from each included source: study design, population / cohort, intervention or exposure, comparator, outcome class, effect direction, effect size, confidence interval or credible interval, p-value, sample size, follow-up duration, risk-of-bias rating. Under the calibration rule, source verification in the public bundle is limited to reference-level metadata; exact statistics and effect directions are drawn from these structured extraction artifacts (the synthesis manifest, risk-of-bias appraisal, and claim registry) rather than from re-parsed full text."},{"id":"claim_12","type":"claim","text":"Per-source risk-of-bias was rated using design-appropriate Cochrane RoB-2 (RCTs), ROBINS-I (non-randomised studies), and AMSTAR-2 (systematic reviews / meta-analyses). Ratings recorded in `risk_of_bias.json`."},{"id":"claim_13","type":"claim","text":"Evidence-tension synthesis: claims grouped by outcome class (cardiometabolic, contextual adjacent evidence, deficiency prevalence, dosing and pharmacokinetics, frailty, immune, longevity, muscle function); within-class agreement, disagreement, and directness gaps surfaced explicitly. Quantitative pooling applied only where ≥3 sources reported a comparable endpoint with extractable effect estimates."},{"id":"claim_14","type":"claim","text":"Source retrieval, claim extraction, evidence routing, and prose drafting were assisted by large language models under a deterministic audit-trail protocol. Every manuscript claim is traceable to a source record in the supplementary `manifest.json`. Final eligibility and interpretation decisions are author-verified."},{"id":"claim_15","type":"claim","text":"Outcome-class note:** Contextual Adjacent Evidence denotes background, boundary-condition, or adjacent-outcome sources. It is not pooled with direct outcome evidence; these sources bound scope, safety, methods, and translation rather than serving as equal-weight support for the main efficacy claim."},{"id":"claim_16","type":"claim","text":"| Evidence domain | Corpus slice | Strongest signal | Directness | Main limitation |"},{"id":"claim_17","type":"claim","text":"| Contextual Adjacent Evidence | n=3; claims=159 | unclear signal in 2/3 sources | 3 review | limited corpus depth in this outcome class |"},{"id":"claim_18","type":"claim","text":"Contextual Adjacent Evidence: n=3; claims=159; mixed signal in 2/3 sources | directness: 3 review; main limitation: no direct clinical anchor."},{"id":"claim_19","type":"claim","text":"The evidence base for vitamin D supplementation and cardiometabolic endpoints includes a large randomized trial, a mechanistic RCT, and two systematic reviews. Peng 2025 performed an integrated transcriptomic and meta-analysis focusing on overweight or obese adults (BMI ≥ 25 kg/m²), while Migliorini 2025 provided a level I systematic review of vitamin D and calcium in women with postmenopausal osteoporosis."},{"id":"claim_20","type":"claim","text":"Quantitative findings across these studies were predominantly null or equivocal. Effect sizes for glycemic and body composition outcomes in Miller 2021 were not reported in extractable numeric form, limiting direct cross-study comparison. Collectively, the point estimates and significance levels across these four studies do not support a robust cardiometabolic benefit of supplementation in the populations studied."},{"id":"claim_21","type":"claim","text":"Mechanistically, vitamin D is hypothesized to influence cardiometabolic risk through effects on insulin sensitivity, inflammatory pathways, and adipocyte differentiation. Miller 2021 tested this pathway by combining vitamin D with whey protein and resistance training, targeting both glycemic control and cardiometabolic risk factors directly. Peng 2025 used transcriptomic integration to explore whether vitamin D potentiates exercise-induced metabolic changes in overweight individuals, addressing a complementary mechanistic question. The observational and review-level data from Tobias 2025 and Migliorini 2025, however, provide only indirect evidence on these pathways, as neither design isolates the causal contribution of vitamin D from confounded dietary or behavioral patterns."},{"id":"claim_22","type":"claim","text":"Within the corpus, the direction of evidence shows notable tension. Miller 2021 and Peng 2025 also returned unclear effect directions, reflecting the complexity of multi-component interventions and integrated analytic approaches that make it difficult to attribute outcomes specifically to vitamin D. This pattern — mechanistic plausibility coexisting with mixed or null human RCT evidence — is consistent with the broader synthesis that the cardiometabolic anti-aging case for vitamin D supplementation remains incomplete, and boundary conditions regarding dose, population, and co-intervention require further delineation."},{"id":"claim_23","type":"claim","text":"The synthesized evidence base for vitamin D supplementation on contextual outcomes encompasses systematic reviews and meta-analyses addressing distinct clinical populations, including community-dwelling older adults at risk for sarcopenia, patients with systemic lupus erythematosus (SLE), and women with polycystic ovary syndrome (PCOS). Prokopidis 2022 conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) evaluating vitamin D monotherapy versus placebo on indices of sarcopenia in older adults. In parallel, Kababi 2025 synthesized twelve studies reporting positive associations between vitamin D supplementation and reduced disease activity in SLE, while Jaafar 2026 reviewed observational data indicating a high prevalence of vitamin D deficiency in women with PCOS. Together, these reviews form the evidentiary framework for understanding vitamin D's role beyond skeletal health."},{"id":"claim_24","type":"claim","text":"Quantitative findings from the sarcopenia-focused review by Prokopidis 2022 present a largely null profile for vitamin D monotherapy."},{"id":"claim_25","type":"claim","text":"Mechanistically, the disparity between null findings in sarcopenia trials and positive signals in autoimmune and endocrine contexts may reflect differences in disease-specific pathways. Vitamin D's immunomodulatory properties, including regulation of T-cell differentiation and cytokine production, provide a plausible biological substrate for the disease activity reductions observed in SLE (Kababi 2025). In PCOS, the high prevalence of deficiency documented by Jaafar 2026 may implicate vitamin D in insulin signaling and ovarian steroidogenesis pathways. Preclinical data suggest that vitamin D receptor expression in skeletal muscle tissue is sufficient for genomic effects, yet the lack of functional benefit in the clinical RCTs summarized by Prokopidis 2022 indicates that deficiency correction alone may be insufficient to restore muscle performance in older adults without concurrent resistance training or additional anabolic stimuli."},{"id":"claim_26","type":"claim","text":"Within the curated corpus, a clear tension emerges between the null-to-minimal effects on sarcopenia indices reported by Prokopidis 2022 and the positive associations for autoimmune and endocrine outcomes documented by Kababi 2025 and Jaafar 2026. This discordance underscores the context-dependent nature of vitamin D's clinical utility: immunomodulatory and endocrine endpoints may be more responsive to supplementation than structural musculoskeletal outcomes, and the boundary conditions governing these differential responses require further delineation through targeted mechanistic and clinical investigation."},{"id":"claim_27","type":"claim","text":"The evidence base for vitamin D supplementation's impact on deficiency prevalence and related metabolic markers is drawn from a heterogeneous collection of study designs."},{"id":"claim_28","type":"claim","text":"Quantitative findings on deficiency correction are divergent across populations and endpoints. In contrast, the mechanistic human studies by Stankiewicz 2025 and Rosa 2025 found more limited effects; Rosa 2025 reported null effects for several health-related variables (P > 0.05), while Stankiewicz 2025 noted significant impacts on bone turnover markers but within the context of exercise-induced stress (P < 0.01)."},{"id":"claim_29","type":"claim","text":"Mechanistically, the efficacy of supplementation appears linked to baseline status and co-interventions. The clear biochemical changes observed by Stankiewicz 2025 (P < 0.01) and Rosa 2025 (P = 0.03) in exercise contexts suggest that physical stress may modulate the biochemical response to supplementation."},{"id":"claim_30","type":"claim","text":"The evidence base for vitamin D supplementation effects on dosing and pharmacokinetics spans diverse clinical contexts, from critically ill patients to those with type 2 diabetes, osteoporosis, and polycystic ovary syndrome. Several systematic reviews and meta-analyses synthesized data from numerous randomized controlled trials, while a direct clinical RCT in overweight and obese patients with chronic low-grade inflammation examined combined supplementation. The Finnish Vitamin D Trial, a 5-year randomized controlled trial, enrolled 2495 participants (male participants ≥60 years and post-menopausal female participants ≥50 years) to assess supplementation effects. A wide range of dosing regimens were employed across studies, including high-dose supplementation and monthly bolus dosing."},{"id":"source_1","type":"source","study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","year":2023,"doi":"10.1007/s00394-022-03038-z","url":"https://doi.org/10.1007/s00394-022-03038-z","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"PURPOSE: Vitamin D supplementation may have non-skeletal health benefits and enhance exercise responsiveness, particularly in those with low vitamin D levels. We determined whether, compared with placebo, vitamin D supplementation taken prior to and during a 12-week exercise program improves physical function, body composition or metabolic health, in overweight and obese older adults with vitamin D deficiency. METHODS: Fifty overweight or obese older adults (mean ± SD age: 60 ± 6 years; BMI 30.6 ± 5.7 kg/m 2 ) with vitamin D deficiency (25-hydroxyvitamin D [25(OH)D] < 50 nmol/L) were recruited. Participants were randomly allocated to receive either vitamin D 3 (4000 IU/day) or matching placebo for 24 weeks. Between weeks 12 and 24, all participants completed multi-modal exercise three days per week while continuing with vitamin D/placebo. Mean changes in physical function (primary outcome: gait speed), body composition and biochemical parameters at weeks 12 and 24 were compared between groups. RESULTS: Vitamin D supplementation, with or without exercise, had no effect on gait speed. From baseline to week 12, vitamin D supplementation increased serum 25(OH)D levels (placebo: 2."},{"id":"source_2","type":"source","study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","year":2023,"doi":"10.3389/fendo.2023.1163671","url":"https://doi.org/10.3389/fendo.2023.1163671","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: Benefits of vitamin D in various cancers have been reported, but its effects on differentiated thyroid cancer (DTC) have not been established. We aimed to analyze the effect of vitamin D supplementation on the prognosis of DTC. METHODS: A retrospective observational cohort study was conducted on 9,739 DTC patients who underwent thyroidectomy from January 1997 to December 2016. Mortality was classified as all-cause, cancer-related, or thyroid cancer-related. Patients were divided into the \"VD group\" (supplemented with vitamin D) and the \"control group\" (without vitamin D supplementation). Propensity score matching was performed in a 1:1 ratio according to age, sex, tumor size, extrathyroidal extension (ETE), and lymph node metastasis (LNM) status, and 3,238 patients were assigned to each group. Kaplan-Meier curves, log-rank test and Cox proportional hazards regression analysis were performed. RESULTS: The follow-up period was 10.7 ± 4.2 years. Clinicopathological variables between two groups were similar except for all-cause ( p <0.001) and total cancer death ( p =0.001)."},{"id":"source_3","type":"source","study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","year":2025,"doi":"10.1038/s41467-025-58721-6","url":"https://doi.org/10.1038/s41467-025-58721-6","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Observational and experimental evidence suggests that vitamin D plays a role in type 2 diabetes (T2D). However, prior randomized supplementation trials are limited to high-risk patients with prediabetes. Here we aim to evaluate whether vitamin D supplementation reduces risk of T2D in a general population of older US adults. The study design is an ancillary analysis (VITAL-T2D) of The Vitamin D and Omega-3 Trial (VITAL), a completed randomized, double-blind, placebo-controlled 2 × 2 trial of daily vitamin D 3 (cholecalciferol; 2000 IU/day) and omega-3 fatty acids (1 g/day) for the primary prevention of cancer and cardiovascular disease. We also conducted a systematic review and meta-analysis of vitamin D trial (≥1000 IU/d cholecalciferol) vs. placebo and T2D risk. We analyzed 22,220 adults with mean age 67.2 years (SD = 7.1) without T2D at enrollment (2011 to 2014), randomized to vitamin D 3 or placebo. Mean body mass index (BMI) was 27.5 kg/m 2 (SD = 5.3), with 51% female and 17% Black race/ethnicity. A subcohort (n = 911) attended in-person visits at baseline and 2 years for glycemic trait analyses. Our meta-analysis included 3 additional trials (5205 participants; 936 T2D cases)."},{"id":"source_4","type":"source","study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","year":2022,"doi":"10.1002/jcsm.12976","url":"https://doi.org/10.1002/jcsm.12976","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is proposed as a potentially effective nutritional intervention to mitigate the risk of sarcopenia. The aim of this systematic review and meta-analysis was to investigate the impact of vitamin D supplementation monotherapy on indices of sarcopenia in community-dwelling older adults. METHODS: A comprehensive search of the literature was conducted in PubMed, Web of Science, Scopus, and Cochrane Library. Eligible randomized controlled trials (RCTs) compared the effect of vitamin D supplementation (as monotherapy) with placebo on indices of sarcopenia in older (>50 years) adults. Using the random effects inverse-variance model, we calculated the mean difference (MD) in handgrip strength (HGS), short physical performance battery (SPPB), timed up and go (TUG), and appendicular lean mass (ALM) between groups. We also calculated the standardized mean difference (SMD) in general muscle strength and general physical performance (composite plot of all muscle strength and physical performance outcomes, respectively) between groups. RESULTS: Ten RCTs were included in the meta-analysis."},{"id":"source_5","type":"source","study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","year":2026,"doi":"10.1136/bmj-2025-087438","url":"https://doi.org/10.1136/bmj-2025-087438","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: To evaluate whether vitamin D supplementation improves live birth rates in women with polycystic ovary syndrome undergoing in vitro fertilisation. DESIGN: Multicentre, double blind, placebo controlled, randomised clinical trial. SETTING: 24 fertility centres in China. PARTICIPANTS: 876 participants with polycystic ovary syndrome undergoing in vitro fertilisation. INTERVENTIONS: Participants were randomised (1:1) to receive vitamin D 4000 IU/day or placebo before in vitro fertilisation for up to 90 days until the trigger day. MAIN OUTCOMES MEASURES: The primary outcome was live birth after the first embryo transfer. Secondary outcomes included serum 25-hydroxyvitamin D (25-OHD) levels on trigger day, pregnancy outcomes, fertility outcomes, and adverse events including severe ovarian hyperstimulation syndrome. RESULTS: Of 876 participants randomised, 865 were included in the modified intention-to-treat analysis, with 435 in the vitamin D group and 430 in the placebo group. Baseline mean serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively."},{"id":"source_6","type":"source","study":"The effects of vitamin D supplementation on frailty in older adults at risk for falls","year":2022,"doi":"10.1186/s12877-022-02888-w","url":"https://doi.org/10.1186/s12877-022-02888-w","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"BACKGROUND: Low serum 25-hydroxyvitamin D [25(OH)D] level is associated with a greater risk of frailty, but the effects of daily vitamin D supplementation on frailty are uncertain. This secondary analysis aimed to examine the effects of vitamin D supplementation on frailty using data from the Study To Understand Fall Reduction and Vitamin D in You (STURDY). METHODS: The STURDY trial, a two-stage Bayesian, response-adaptive, randomized controlled trial, enrolled 688 community-dwelling adults aged ≥ 70 years with a low serum 25(OH)D level (10-29 ng/mL) and elevated fall risk. Participants were initially randomized to 200 IU/d (control dose; n = 339) or a higher dose (1000 IU/d, 2000 IU/d, or 4000 IU/d; n = 349) of vitamin D3. Once the 1000 IU/d was selected as the best higher dose, other higher dose groups were reassigned to the 1000 IU/d group and new enrollees were randomized 1:1 to 1000 IU/d or control group. Data were collected at baseline, 3, 12, and 24 months. Frailty phenotype was based on number of the following conditions: unintentional weight loss, exhaustion, slowness, low activity, and weakness (≥ 3 conditions as frail, 1 or 2 as pre-frail, and 0 as robust)."},{"id":"source_7","type":"source","study":"Potential Modulation of Inflammation and Physical Function by Combined Probiotics, Omega-3 Supplementation and Vitamin D Supplementation in Overweight/Obese Patients with Chronic Low-Grade Inflammation: A Randomized, Placebo-Controlled Trial","year":2023,"doi":"10.3390/ijms24108567","url":"https://doi.org/10.3390/ijms24108567","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Obesity is characterized by low-grade inflammation and increased gut permeability. Here, we aim to evaluate the effect of a nutritional supplement on these parameters in subjects with overweight and obesity. A double-blinded, randomized clinical trial was conducted in 76 adults with overweight or obesity (BMI 28 to 40) and low-grade inflammation (high-sensitivity C-reactive protein (hs-CRP) between 2 and 10 mg/L). The intervention consisted of a daily intake of a multi-strain probiotic of Lactobacillus and Bifidobacterium , 640 mg of omega-3 fatty acids (n-3 FAs), and 200 IU of vitamin D ( n = 37) or placebo ( n = 39), administered for 8 weeks. hs-CRP levels did not change post-intervention, other than an unexpected slight increase observed in the treatment group. Interleukin (IL)-6 levels decreased in the treatment group ( p = 0.018). The plasma fatty acid (FA) levels of the arachidonic acid (AA)/eicosapentaenoic acid (EPA) ratio and n-6/n-3 ratio ( p < 0.001) decreased, and physical function and mobility improved in the treatment group ( p = 0.006)."},{"id":"source_8","type":"source","study":"Can vitamin D supplementation affect cardiometabolic factors in children and adolescence with overweight and obesity? A grade-assessed systematic review and meta-analysis of randomized controlled trials","year":2025,"doi":"10.1186/s12887-025-05795-2","url":"https://doi.org/10.1186/s12887-025-05795-2","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D have been proposed as a supplement to improve cardiometabolic risk factors in obese/overweight children and adolescents. However, findings evidence remains inconsistent. This meta-analysis aimed to assess the effects of vitamin D supplementation on cardiometabolic risk factors in obese/overweight children and adolescents. METHODS: A systematic review of PubMed, Embase, Scopus, Web of Science, Cochrane Library, and Google Scholar up to April 2025 was searched. This study aimed to evaluate the effect of vitamin D supplementation on cardiometabolic factors including anthropometric indices, glycemic state and lipid profile. Data were pooled using a random-effects model to calculate weighted mean differences (WMDs) and 95% confidence intervals (CIs). RESULTS: Nine studies with 440 participants were included. The meta-analysis revealed that vitamin D supplementation no significantly improved BMI, BMI-Z, FBS, insulin, HOMA-IR, QUICKI, TG, TC, and LDL-C. However, it was accompanied with a significant reduction in HDL-C level."},{"id":"source_9","type":"source","study":"Concurrent effects of high-intensity interval training and vitamin D supplementation on bone metabolism among women diagnosed with osteoporosis: a randomized controlled trial","year":2025,"doi":"10.1186/s12891-025-08275-x","url":"https://doi.org/10.1186/s12891-025-08275-x","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Osteoporosis is often responsible for bone fragility and increased fracture risk due to the micro-architectural deterioration of bone tissue. In addition to nutritional supplements, exercise is considered an adjunct factor in safeguarding bone health. This study aimed to investigate the effects of 16-week high-intensity interval training (HIIT) and vitamin D supplementation on bone mineral density (BMD) in women with osteoporosis. TRIAL DESIGN: This study used a four-arm pretest-posttest experimental randomized controlled design. METHODS: One hundred twenty sedentary women aged (30-50 years), diagnosed with osteoporosis were recruited in this study. Patients were randomly classified into four groups with 30 patients in each group: control group (normal daily activities), exercise group (HIIT-exercise for 16 weeks), Vitamin D group (vitamin D 800IU/ day for 16 weeks), and concurrent group (HIIT exercise plus vitamin D for 16 weeks). Anthropometric measurements, BMD, and serum levels of vitamin 25-(OH) D, Osteocalcin, s-BAP, and calcium were estimated in all participants before and after exercise training."},{"id":"source_10","type":"source","study":"Effectiveness of Vitamin D Supplementation on Biochemical, Clinical, and Inflammatory Parameters in Patients with Different Types of Diabetes: A Systematic Review and Meta-Analysis","year":2025,"doi":"10.3390/nu17182991","url":"https://doi.org/10.3390/nu17182991","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"Background and Aims: Numerous clinical and observational studies have examined the role of vitamin D in glycemic control and metabolic regulation among diabetic patients, but findings remain inconsistent. This meta-analysis aimed to assess the effects of vitamin D supplementation on glycosylated hemoglobin (HbA1c%), HOMA-IR, HOMA-β, LDL cholesterol, total cholesterol, triglycerides, fasting insulin, fasting plasma glucose, C-reactive protein, and the likelihood of reversion to normoglycemia in prediabetic individuals. Methods: A comprehensive search of multiple databases was performed using keywords including \"diabetes mellitus,\" \"type 2 diabetes,\" \"vitamin D supplementation,\" and \"VD supplementation.\" Twenty studies met the inclusion criteria. Results: Vitamin D supplementation was associated with significant improvements across several parameters, including HOMA-β (SMD = 0.71; 95% CI: 0.63-0.80; p < 0.00001), HDL cholesterol (SMD = 0.07; 95% CI: 0.05-0.09; p < 0.00001), and others (SMD = -0.40; 95% CI: -0.45 to -0.34; p < 0.00001)."},{"id":"source_11","type":"source","study":"Vitamin D supplementation in critically ill patients: a meta-analysis","year":2025,"doi":"10.3389/fnut.2025.1505616","url":"https://doi.org/10.3389/fnut.2025.1505616","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D is commonly used in clinical practice, while its clinical significance in critically ill patients remains controversial. Therefore, we aimed to perform a systemic review and meta-analysis to investigate the effect of vitamin D on this patient population. METHODS: We searched for randomized controlled trials (RCTs) in PubMed, Embase, and the Cochrane Library databases from inception until August 15, 2024. Studies evaluating critically ill adult patients who received vitamin D compared to controls were included. The primary outcome was short-term mortality. We used the Cochrane risk of bias tool and GRADE system to evaluate the study quality and evidence. Secondary outcomes were changes in serum 25-hydroxyvitamin D levels, mechanical ventilation (MV) duration, and length of stay (LOS) in the ICU or hospital. We also conducted meta-regression, subgroup analyses, and trial sequential analysis (TSA) to explore the potential heterogeneity among the included trials. RESULTS: Nineteen RCTs with 2,754 patients were eligible."},{"id":"source_12","type":"source","study":"Effect of vitamin D supplementation on clinical outcomes in adult patients with COVID‐19: A GRADE‐assessed systematic review and meta‐analysis of randomized controlled trials","year":2024,"doi":"10.1002/prp2.70013","url":"https://doi.org/10.1002/prp2.70013","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"The COVID-19 pandemic has emerged as a major global health crisis. Vitamin D, a crucial fat-soluble vitamin, has been recommended for COVID-19 patients, though evidence of its effectiveness is inconsistent. This systematic literature review and meta-analysis aimed to evaluate the impact of vitamin D supplementation on COVID-19-related outcomes. A comprehensive search was conducted across PubMed, Scopus, Web of Science, Embase, and Cochrane databases. Primary outcomes included mortality and hospital length of stay, while secondary outcomes encompassed C-reactive protein (CRP), ferritin, D-dimer, hemoglobin (Hb) concentrations, and lymphocyte, neutrophil, and platelet counts. Data analysis was performed using Stata™ Version 14. A total of 16 trials were analyzed. The meta-analysis revealed that vitamin D supplementation significantly reduced hospital length of stay (mean difference = -1.16; 95% confidence interval [CI]: -2.23, -0.09; p = .033) with significant heterogeneity (I 2 = 69.2%, p = .002). Subgroup analysis showed a more pronounced reduction in studies with vitamin D dosages ≤10 000 international units (IU) (mean difference = -1.27; 95% CI: -1.96, -0.57; p < ."},{"id":"source_13","type":"source","study":"The Impact of Vitamin D Supplementation on Fasting Plasma Glucose, Insulin Sensitivity, and Inflammation in Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis","year":2025,"doi":"10.3390/nu17152489","url":"https://doi.org/10.3390/nu17152489","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"Background/Objectives : Vitamin D supplementation has shown promise in managing type 2 diabetes mellitus (T2DM), while the simultaneous impact on glycemic control and inflammation in T2DM remains poorly understood. This study aimed to investigate the potential role of vitamin D supplementation in managing T2DM using fasting plasma glucose (FPG), insulin levels, HOMA-IR, HOMA-B, HbA1c, and Hs-CRP as the biomarkers. Methods : Original articles from Scopus, Pubmed, Cochrane Library, Epistemonikos, and ScienceDirect published between 2014 and 2024 were the sources. Inclusion criteria included studies conducted as clinical trials or randomized controlled trials involving adult patients diagnosed with T2DM undergoing treatment with vitamin D. The risk of bias was evaluated using the ROB-2 tool and meta-analysis was conducted to quantitatively synthesize the results across the studies using pooled effect sizes and confidence intervals. Results : Nine studies were included in the meta-analysis. Significant differences were found at 12-week follow-up in insulin level (MD(-3.59) [95% CI: -6.93, -0.25]), HOMA-B (MD(-50.35) [95% CI: -92.29, -8.41]), hs-CRP (-2.51 [95% CI: -3.45, -1."},{"id":"source_14","type":"source","study":"Role of vitamin D supplementation in prevention of new onset atrial fibrillation in post-coronary artery bypass graft patients in vitamin D deficient and insufficient populations: a systematic review and meta-analysis","year":2025,"doi":"10.1186/s12872-025-05223-4","url":"https://doi.org/10.1186/s12872-025-05223-4","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Postoperative atrial fibrillation (POAF) is a common complication following coronary artery bypass grafting (CABG), contributing to increased morbidity, prolonged hospitalization, and elevated healthcare costs. Emerging evidence suggests that vitamin D (Vit. D), via its anti-inflammatory effects and modulation of the renin-angiotensin-aldosterone system (RAAS), may have a cardioprotective role. OBJECTIVE: This systematic review and meta-analysis aimed to evaluate the efficacy of preoperative Vit. D supplementation in reducing the incidence of POAF among CABG patients, with a focus on populations with Vit. D deficiency and insufficiency. METHODS: Our study was conducted in accordance with the PRISMA 2020 Guidelines. The electronic databases PubMed, Cochrane Library and Google Scholar were searched from 2014 to 2024. Randomized controlled trials and retrospective observational studies involving adult subjects, evaluating Vit. D deficient and/or insufficient patients who have undergone CABG and received Vit."},{"id":"source_15","type":"source","study":"A meta-analysis of the effects of vitamin D supplementation on endocrine metabolic and inflammatory markers in patients with polycystic ovarian syndrome","year":2026,"doi":"10.1097/MD.0000000000046892","url":"https://doi.org/10.1097/MD.0000000000046892","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: To evaluate the effects of vitamin D on the endocrine, metabolic, and inflammatory markers providing new PCOS treatment ideas. METHODS: PubMed, EMBASE, Web of Science, and Cochrane Library were systematically searched for vitamin D treatment studies in PCOS patients from establishment to 12/2022 using vitamin D, polycystic ovary syndrome, PCOS, etc, as search terms. Two researchers independently screened the retrieved literature, extracted the data, and finally performed a meta-analysis of these data with Review Manager 5.4 software to calculate all-parameter weighted mean difference (WMDs) and 95% confidence intervals (CIs) using a fixed-effects or random-effect models. RESULTS: The 10 included articles mainly studied the effects of vitamin D and placebo control treatment on endocrine, metabolic and inflammatory indicators in PCOS patients. Meta-analysis results showed that compared to placebo, vitamin D reduces the homeostatic model assessment-insulin resistance index (HOMA-IR) (MD = -0.47; 95% CI: -0.66 to -0.28; P < .00001), fasting serum insulin (FBI) (MD = -1.25; 95% CI: -2.44 to -0.06; P = .04), hypersensitive C-reactive protein (hs-CRP) (MD = -1.18; 95% CI: -2."},{"id":"source_16","type":"source","study":"Dose–response effects of vitamin D supplementation on vitamin D status, glycosylated hemoglobin and total cholesterol in patients with diabetes mellitus: a systematic review and meta-analysis","year":2025,"doi":"10.3389/fnut.2025.1663019","url":"https://doi.org/10.3389/fnut.2025.1663019","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"The impact of vitamin D levels on glycemic control and lipid metabolism in diabetic patients has received widespread attention. However, currently, there was no unified standard for vitamin D supplementation dosages, with significant variations among guideline recommendations. For instance, the 2022 ESPEN Guidelines recommended a daily supplementation of 1,500-5,000 International Units (IU) for patients at risk of vitamin D deficiency or who repeatedly experience vitamin D deficiency; however, guidelines from Italy suggested a daily supplement dose of 800-1,000 IU for patients with vitamin D deficiency. In this study, we searched the PubMed, Web of Science, Embase, Cochrane Library, CBM, CNKI, and Wanfang databases from their inception to 31 May 2024 for literature. The effects of different supplementation levels on vitamin D levels, glycosylated hemoglobin (HbA1c) levels and total cholesterol (TC) levels were analyzed using random-effects and fixed-effects models, respectively, and we applied the Modified Jadad Scale and the Newcastle-Ottawa Scale (NOS) score to evaluate the quality of the RCT studies and retrospective analyses, respectively."},{"id":"source_17","type":"source","study":"Role of Vitamin D Supplementation in Chronic Liver Disease: A Systematic Review and Meta-Analysis of Randomized Controlled Trials","year":2025,"doi":"10.1093/nutrit/nuaf117","url":"https://doi.org/10.1093/nutrit/nuaf117","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"CONTEXT: Vitamin D deficiency is highly prevalent in chronic liver disease. Although international societies recommend vitamin D supplementation in cases of proven deficiency, the impact of vitamin D on chronic liver disease remains uncertain. OBJECTIVE: Our aim was to evaluate the effects of vitamin D supplementation in patients with chronic liver disease by conducting a systematic review and meta-analysis of randomized controlled trials (RCTs). DATA SOURCES: We systematically searched PubMed, EMBASE and the Cochrane Library on July 2, 2024. DATA EXTRACTION: Our primary outcomes involved survival, controlled attenuation parameter (CAP), liver stiffness measurement (LSM), and effects on changes in liver enzymes. Secondary outcomes included lipid profile and homeostasis model assessment of insulin resistance (HOMA-IR), among others. The pooled risk ratio (RR), mean difference (MD), and corresponding 95% CIs were calculated using the random-effects model. DATA ANALYSIS: Forty-six RCTs were included, comprising 4084 patients. When we compared the vitamin D group with the control, the RR for overall survival was 1.14 (95% CI, 0.85-1.54; 4 RCTs) at 6 months and 0.99 (95% CI, 0.83-1."},{"id":"source_18","type":"source","study":"Effects of Maternal Vitamin D Supplementation on Childhood Health","year":2025,"doi":"10.1210/endrev/bnaf001","url":"https://doi.org/10.1210/endrev/bnaf001","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Vitamin D deficiency during pregnancy is associated with an increased risk of health issues in the offspring. Accordingly, recent Endocrine Society guidelines strongly support supplementation in pregnancy, also underlining that without consensus on optimal maternal vitamin D levels, routine screening is currently irrelevant. Knowledge of organ-specific effects of vitamin D and its association with maternal vitamin D status may aid in optimizing vitamin D supplementation. This systematic review outlines the proposed next-generation effects of vitamin D supplementation ≥400 IU/d and explores whether such effects are attributed to a specific maternal vitamin D level obtained during pregnancy. A systematic literature search was conducted in PubMed and Embase according to the PRISMA guidelines, focusing on health outcomes from 10 days postpartum and beyond. Of the 2383 screened articles, 39 were included. In 11 of 16 studies, vitamin D supplementation reduced respiratory tract infections in the first years of life. Growth or bone development benefits were observed in 6 of 12 studies."},{"id":"source_19","type":"source","study":"Effect of the vitamin D supplementation on clinical outcomes and inflammatory status in COVID-19 patients: an umbrella review","year":2025,"doi":"10.1186/s40795-025-01060-y","url":"https://doi.org/10.1186/s40795-025-01060-y","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"INTRODUCTION: The role of vitamin D supplementation in modulating clinical outcomes and inflammatory responses in COVID- 19 patients has garnered significant interest. This umbrella review consolidates current evidence to evaluate the association between vitamin D supplementation and COVID- 19-related outcomes. METHODS: A comprehensive search was conducted across multiple databases to identify relevant systematic reviews and meta-analyses. Studies assessing the impact of vitamin D supplementation on disease severity, mortality, hospitalization, and inflammatory markers in COVID- 19 patients were included. Methodological quality was assessed using standardized tools. RESULTS: The findings suggest that vitamin D supplementation may be associated with reduced mortality and improved clinical outcomes in COVID- 19 patients. Several studies reported a decrease in inflammatory markers, such as C-reactive protein and interleukin- 6, following supplementation. However, variations in study design, dosage regimens, and baseline vitamin D status limit the generalizability of results."},{"id":"source_20","type":"source","study":"Vitamin D supplementation and prevention of cardiovascular disease and cancer in the Finnish Vitamin D Trial: a randomized controlled trial","year":2022,"doi":"10.1093/ajcn/nqab419","url":"https://doi.org/10.1093/ajcn/nqab419","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"BACKGROUND: Vitamin D insufficiency is associated with risks of cardiovascular diseases (CVD) and cancer in observational studies, but evidence for benefits with vitamin D supplementation is limited. OBJECTIVES: To investigate the effects of vitamin D3 supplementation on CVD and cancer incidences. METHODS: The study was a 5-year, randomized, placebo-controlled trial among 2495 male participants ≥60 years and post-menopausal female participants ≥65 years from a general Finnish population who were free of prior CVD or cancer. The study had 3 arms: placebo, 1600 IU/day, or 3200 IU/day vitamin D3. Follow-up was by annual study questionnaires and national registry data. A representative subcohort of 551 participants had more detailed in-person investigations. The primary endpoints were incident major CVD and invasive cancer. Secondary endpoints included the individual components of the primary CVD endpoint (myocardial infarction, stroke, and CVD mortality), site-specific cancers, and cancer death. RESULTS: During the follow-up, there were 41 (4.9%), 42 (5.0%), and 36 (4.3%) major CVD events in the placebo, 1600 IU/d (compared with placebo: HR: 0.97; 95% CI: 0.63-1.49; P = 0."},{"id":"source_21","type":"source","study":"Falls and physical function in older patients with Benign Paroxysmal Positional Vertigo (BPPV): findings from a placebo controlled, double blinded randomized control trial (RCT) investigating efficacy of vitamin D treatment in lowering the recurrence rate of BPPV","year":2025,"doi":"10.1007/s40520-025-02938-4","url":"https://doi.org/10.1007/s40520-025-02938-4","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Benign Paroxysmal Positional Vertigo (BPPV) is the commonest cause of vertigo in older adults. Due to its high incidence in older adults presenting with falls, vestibular assessment is recommended in the World Guidelines for Falls Prevention. There is a paucity of evidence in well conducted randomised controlled trials (RCTs) to evaluate vitamin D for prevention of BPPV recurrence in relation to falls and function. AIMS: Primary outcome: does vitamin D supplementation and dietary interventions in combination with standard care impact falls, fear of falling and function in patients with BPPV. METHODS: Post hoc analyses of phase IIa single centre, placebo controlled, double blind RCT evaluating vitamin D supplementation with diet and Canalith Repositioning Procedure (CRP) [Group A] versus diet alone with CRP [Group B] in reducing BPPV recurrence rates and the consequent effects on falls and function. RESULTS: 53 participants were recruited. 14 were vitamin D replete at baseline (Group C) with remaining 39 randomised into Groups A and B. Group A had better 5x sit to stand time and 0.75 fewer clinical BPPV recurrences per one person year (P = 0.035) compared to Group B."},{"id":"source_22","type":"source","study":"Vitamin D supplementation and major cardiovascular events: D-Health randomised controlled trial","year":2023,"doi":"10.1136/bmj-2023-075230","url":"https://doi.org/10.1136/bmj-2023-075230","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVE: To investigate whether supplementing older adults with monthly doses of vitamin D alters the incidence of major cardiovascular events. DESIGN: Randomised, double blind, placebo controlled trial of monthly vitamin D (the D-Health Trial). Computer generated permuted block randomisation was used to allocate treatments. SETTING: Australia from 2014 to 2020. PARTICIPANTS: 21 315 participants aged 60-84 years at enrolment. Exclusion criteria were self-reported hypercalcaemia, hyperparathyroidism, kidney stones, osteomalacia, sarcoidosis, taking >500 IU/day supplemental vitamin D, or unable to give consent because of language or cognitive impairment. INTERVENTION: 60 000 IU/month vitamin D 3 (n=10 662) or placebo (n=10 653) taken orally for up to five years. 16 882 participants completed the intervention period: placebo 8270 (77.6%); vitamin D 8552 (80.2%). MAIN OUTCOME MEASURES: The main outcome for this analysis was the occurrence of a major cardiovascular event, including myocardial infarction, stroke, and coronary revascularisation, determined through linkage with administrative datasets. Each event was analysed separately as secondary outcomes."},{"id":"source_23","type":"source","study":"The effects of magnesium and vitamin D/E co-supplementation on inflammation markers and lipid metabolism of obese/overweight population: a systematic review and meta-analysis","year":2025,"doi":"10.3389/fnut.2025.1563604","url":"https://doi.org/10.3389/fnut.2025.1563604","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Inflammatory reactions can induce or facilitate the occurrence and development of various diseases in the human body. It is crucial to regulate and actively control inflammatory factors to maintain the health of an individual. Vitamins D and E and magnesium ions may potentially inhibit inflammatory responses. Abnormal lipid metabolism is known to affect people's health and lead to serious diseases. Magnesium and vitamin E are also known to possess anti-lipidemic properties. It is worth noting that the prevalence and disease burden of some diseases are related to overweight and obesity. This systematic review and meta-analysis assesses the impact of magnesium and vitamin D or vitamin E co-supplementation on inflammation and lipid metabolism markers of obese/overweight population in randomized controlled trials (RCTs). METHODS: A comprehensive search was conducted across PubMed, Web of Science, Embase and Cochrane databases until January 2024 to investigate the impact of simultaneous supplementation of magnesium and vitamin D/E."},{"id":"source_24","type":"source","study":"Single high-dose vitamin D supplementation impacts ultramarathon-induced changes in serum levels of bone turnover markers: a double-blind randomized controlled trial","year":2025,"doi":"10.1080/15502783.2025.2561661","url":"https://doi.org/10.1080/15502783.2025.2561661","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"BACKGROUND: Recent studies indicate a protective role of vitamin D supplementation against sports performance-induced dysregulation of body homeostasis. However, the effects of a single high dose of vitamin D on changes in bone formation and resorption markers due to ultramarathon running have yet to be explored. This study aimed to analyze the effect of a single high-dose vitamin D supplementation on serum levels of bone turnover markers after a mountain ultramarathon run. METHODS: In this clinical trial (reg. number NCT03417700), 35 semiprofessional male ultramarathon runners were assigned into two groups: supplemented group, administered a single high dose of vitamin D 3 (cholecalciferol, 150,000 IU) in vegetable oil 24 h before the start of the run ( n = 16), and placebo group ( n = 19), administered placebo solution 24 h before the start of the run. Blood samples were collected for analysis at three timepoints: 24 h before, immediately after, and 24 h after the run. RESULTS: Serum 25(OH)D 3 level significantly increased ( p ≤ 0.05.) after the ultramarathon in both groups. The increase was more pronounced in the supplemented population, especially 24 h after the run (147."},{"id":"source_25","type":"source","study":"Vitamin D Supplementation and Its Impact on Mortality and Cardiovascular Outcomes: Systematic Review and Meta-Analysis of 80 Randomized Clinical Trials","year":2023,"doi":"10.3390/nu15081810","url":"https://doi.org/10.3390/nu15081810","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: The impact of vitamin D supplementation on cardiovascular outcomes and mortality risk reduction remains unclear due to conflicting study findings. METHODS: We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs), published between 1983 and 2022, that reported the effect of vitamin D supplementation in adults versus placebo or no treatment on all-cause mortality (ACM), cardiovascular mortality (CVM), non-cardiovascular mortality (non-CVM), and cardiovascular morbidities. Only studies with a follow-up period longer than one year were included. The primary outcomes were ACM and CVM. Secondary outcomes were non-CVM, myocardial infarction, stroke, heart failure, and major or extended adverse cardiovascular events. Subgroup analyses were performed according to low-, fair- and good-quality RCTs. RESULTS: Eighty RCTs were assessed, including 82,210 participants receiving vitamin D supplementation and 80,921 receiving placebo or no treatment. The participants' mean (SD) age was 66.1 (11.2) years, and 68.6% were female. Vitamin D supplementation was associated with a lower risk of ACM (OR: 0.95 [95%CI 0.91-0.99] p = 0."},{"id":"source_26","type":"source","study":"High-dose versus standard-dose vitamin D supplementation in older adults with COVID-19 (COVIT-TRIAL): A multicenter, open-label, randomized controlled superiority trial","year":2022,"doi":"10.1371/journal.pmed.1003999","url":"https://doi.org/10.1371/journal.pmed.1003999","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation has been proposed as a treatment for Coronavirus Disease 2019 (COVID-19) based on experimental data and data from small and uncontrolled observational studies. The COvid19 and VITamin d TRIAL (COVIT-TRIAL) study was conducted to test whether a single oral high dose of cholecalciferol (vitamin D3) administered within 72 hours after the diagnosis of COVID-19 improves, compared to standard-dose cholecalciferol, the 14-day overall survival among at-risk older adults infected with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). METHODS AND FINDINGS: This multicenter, randomized, controlled, open-label, superiority trial involved collaboration of 9 medical centers in France. Patients admitted to the hospital units or living in nursing homes adjacent to the investigator centers were eligible if they were ≥65 years, had SARS-CoV-2 infection of less than 3 days, and at least 1 COVID-19 worsening risk factor (among age ≥75 years, SpO2 ≤94%, or PaO2/FiO2 ≤300 mm Hg)."},{"id":"source_27","type":"source","study":"Vitamin D Supplementation Modulates Platelet-Mediated Inflammation in Subjects With Type 2 Diabetes: A Randomized, Double-Blind, Placebo-Controlled Trial","year":2022,"doi":"10.3389/fimmu.2022.869591","url":"https://doi.org/10.3389/fimmu.2022.869591","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"BACKGROUND: Recently, our group identified increased platelet-mediated inflammation in type 2 diabetes (T2DM) patients, and it is a well-established risk factor for diabetes complications, particularly for the development of cardiovascular diseases (CVD). Furthermore, vitamin D is reported to play an important role in the modulation of platelet hyperactivity and immune function, although the effect of vitamin D on platelet-mediated inflammation is not well studied. Hence, we aimed to investigate the effect of vitamin D supplementation on platelet-mediated inflammation in T2DM patients. METHODS: After screening a total of 201 subjects, our randomized, double-blind, placebo-controlled trial included 59 vitamin-D-deficient T2DM subjects, and the participants were randomly assigned to placebo ( n = 29) or vitamin D3 ( n = 30) for 6 months. Serum vitamin D metabolite levels, immunome profiling, platelet activation, and platelet-immune cell aggregate formation were measured at baseline and at the end of the study. Similarly, the serum levels of inflammatory cytokines/chemokines were assessed by a multiplex assay."},{"id":"source_28","type":"source","study":"Effect of Vitamin D Supplementation on Cardiometabolic Outcomes in Older Australian Adults—Results from the Randomized Controlled D-Health Trial","year":2026,"doi":"10.3390/nu18020357","url":"https://doi.org/10.3390/nu18020357","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"Background/Objectives : Observational studies have found inverse associations between 25-hydroxyvitamin D concentration and risk of hypertension, hypercholesterolemia and type 2 diabetes (T2D). More robust evidence from large-scale randomized controlled trials, however, is limited or inconclusive. Methods : The D-Health Trial (N = 21,315) is a randomized, double-blind, placebo-controlled trial of supplementation with monthly doses of 60,000 international units of oral vitamin D 3 , conducted in Australians aged 60-84 years. Commencing treatment with anti-hypertensive, lipid-modifying, or anti-diabetic drugs was used as a surrogate for incident hypertension, hypercholesterolemia, and T2D, respectively. Outcomes were ascertained via linkage with the Australian Pharmaceutical Benefits Scheme database. Follow-up began 6 months after randomization; we excluded participants without linked data, and those who were prevalent cases or who died prior to start of follow-up. Flexible parametric survival models were used to estimate the effect of vitamin D supplementation on each outcome. Results : We included 10,964 participants (vitamin D, n = 5456 [49.8%]; placebo, n = 5508 [50."},{"id":"source_29","type":"source","study":"Effects of vitamin D supplementation on glucose metabolism and pregnancy outcomes in GDM: a systematic review and meta-analysis","year":2026,"doi":"10.3389/fmed.2026.1743776","url":"https://doi.org/10.3389/fmed.2026.1743776","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: This systematic review and meta-analysis aimed to evaluate the efficacy and safety of vitamin D supplementation on glucose metabolism and pregnancy outcomes in gestational diabetes mellitus (GDM). METHODS: To achieve this, we searched Chinese and English databases (PubMed, EMBASE, Cochrane Library, China National Knowledge Infrastructure, Wanfang Med Online, and VipInfo Chinese Journal Service Platform) up to September 2024. Data were analyzed using Review Manager 5.3 and Stata 15.1, presenting continuous variables as standardized mean difference (SMD) and dichotomous variables as relative risk (RR), both with 95% confidence intervals (CI). The Cochrane tool assessed the risk of bias. RESULTS: Twenty studies involving 1,737 patients were included. Meta-analysis showed that compared to placebo, vitamin D supplementation significantly reduced fasting glucose (SMD: -1.01, p = 0.0002), 2-h postprandial glucose (SMD: -0.89, p = 0.0002), insulin levels (SMD: -0.64, p < 0.0001), and insulin resistance (SMD: -0.91, p = 0.001). Furthermore, it was associated with lower incidences of cesarean delivery (RR: 0.68, p < 0.0001), forceps-assisted delivery (RR: 0.44, p = 0."},{"id":"source_30","type":"source","study":"Vitamin D Receptor Polymorphisms and the Effect of Vitamin D Supplementation on Diabetes Risk Among Adults With Prediabetes","year":2026,"doi":"10.1001/jamanetworkopen.2026.7332","url":"https://doi.org/10.1001/jamanetworkopen.2026.7332","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"IMPORTANCE: Achieving and maintaining a serum 25-hydroxyvitamin D (25[OH]D) level of 40 ng/mL or higher, compared with 20 to 30 ng/mL, may lower diabetes risk among adults with prediabetes. It is not known whether a genetically defined subgroup is more likely to experience benefits from targeting higher 25(OH)D levels with vitamin D3 supplementation. OBJECTIVE: To assess the role of common polymorphisms of the vitamin D receptor (VDR) in the association between supplementation with 4000 IU/d of vitamin D3 and the risk of diabetes among adults with prediabetes. DESIGN, SETTING, AND PARTICIPANTS: This genetic association study conducted a VDR genotype analysis of 3 common polymorphisms-ApaI, BsmI, and FokI-among 2098 participants in the Vitamin D and Type 2 Diabetes (D2d) clinical trial with available intratrial 25(OH)D levels and genotyping. The D2d trial was conducted from October 1, 2013, to November 28, 2018, with statistical analysis performed from January 3 to November 30, 2025. EXPOSURES: Receipt of 4000 IU/d of vitamin D3 vs placebo for a median of 2.5 years (IQR, 1.8-3.5 years)."},{"id":"source_31","type":"source","study":"Effect of vitamin D supplementation on COVID-19 outcomes: an umbrella review of systematic reviews","year":2025,"doi":"10.3389/fnut.2025.1559471","url":"https://doi.org/10.3389/fnut.2025.1559471","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D is suggested as a supportive therapy to reduce the severity of COVID-19 due to its immunomodulatory and anti-inflammatory effects. However, its effect on critical outcomes, such as ICU admissions and mortality, shows significant variation across randomized clinical trials and meta-analyses. OBJECTIVES: To summarize the influence of vitamin D supplementation on ICU admissions and mortality among COVID-19 patients. METHODS: Overall, 21 eligible studies were retrieved using a comprehensive search from Scopus, PubMed, and Web of Science. A citation matrix was developed, revealing a Corrected Covered Area (CCA) of 0.54, indicating moderate overlap. Fixed-effects models were applied to data with low heterogeneity (ICU admissions: Q = 10.87, p = 0.33), while random-effects models were used for mortality outcomes (Q = 27.23, p = 0.006). Pooled odds ratios (OR) with 95% confidence intervals (CI) quantified the overall effects. RESULTS: Vitamin D supplementation was associated with a significant 38% reduction in ICU admissions (OR = 0.62; 95% CI: 0.54-0.71) and a 33% reduction in mortality risk (OR = 0.67; 95% CI: 0.56-0.79)."},{"id":"source_32","type":"source","study":"Association between ionized calcium levels and 3-months mortality in geriatric patients hospitalized for COVID-19","year":2025,"doi":"10.1016/j.jnha.2025.100661","url":"https://doi.org/10.1016/j.jnha.2025.100661","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"OBJECTIVES: The aim of this study was to determine an association between ionized calcium (CaI) levels and mortality 3 months after Covid-19 infection in geriatric population. DESIGN: Observational retrospective cohort study. SETTING AND PARTICIPANTS: One hundred and seventy-nine patients hospitalized in the geriatric acute care unit of Angers University Hospital were included. This specific unit specifically dedicated to COVID-19 patients was opened for 2 periods : from March 1, 2020 to June 30, 2020 and from October 1, 2020 to March 29, 2021. Covariates considered were: age, sex, Iso-Resources Groups (GIR) score ≤ 3, Parathyroid hormone (PTH), C-Reactive Protein (CRP), severe undernutrition defined as albumin < 30 g/L, history of cancer, history of cardiomyopathy, severe chronic renal failure (defined as clearance < 30 ml/min), Ordinal Scale for Clinical Improvement (OSCI) score, use of systemic corticosteroids and usual vitamin D supplementation. Direct potentiometry was also used as a covariate."},{"id":"source_33","type":"source","study":"Vitamin D Supplementation in Children with Asthma: An Umbrella Review","year":2026,"doi":"10.3390/nu18101560","url":"https://doi.org/10.3390/nu18101560","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Growing evidence suggests that vitamin D plays a role in the pathophysiology of childhood asthma. However, its effectiveness in reducing asthma exacerbations and improving asthma-related outcomes remains controversial. METHODS: We systematically searched PubMed, Embase, and the Cochrane Library from inception to 25 February 2026. Meta-analyses of randomized controlled trials (RCTs) evaluating the effects of vitamin D supplementation on any health outcomes in children with asthma were included. Methodological quality was assessed using the AMSTAR 2 tool. The credibility of evidence was evaluated using pre-specified evidence classification criteria, and the certainty of evidence was graded using the GRADE approach. RESULTS: A total of 14 systematic reviews were included, of which one was rated as high quality, six as low quality, and seven as critically low quality according to AMSTAR 2. Vitamin D supplementation significantly increased serum 25-hydroxyvitamin D levels in children with asthma (MD = 10.68 ng/mL; 95% CI, 6.30 to 15.05; n = 8 RCTs), although the evidence was of low credibility (class IV) and very low certainty."},{"id":"source_34","type":"source","study":"Short-term and long-term effects of vitamin D supplementation for preterm infants: a systematic review and meta-analysis","year":2025,"doi":"10.1038/s41372-025-02440-9","url":"https://doi.org/10.1038/s41372-025-02440-9","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"Meta-analysis conducted to evaluate the effectiveness of high-dose (≥800 IU/day) and low-dose (<800 IU/day) vitamin D supplementation on preterm infants. Study quality was evaluated using the Revised Cochrane risk-of-bias tool 2 for randomized trials. 21 studies included 1130 infants. Regarding short-term (before 40 weeks' postmenstrual age [PMA] or at discharge) outcomes, high-dose vitamin D supplementation was associated with increased serum 25-hydroxyvitamin D (25[OH]D) levels (mean difference 15.62 [13.35-17.88]) and growth velocities, as well as decreased vitamin D deficiency (VDD), skeletal hypomineralization, and mortality. In the subgroup analysis of high-dose supplementation stratified by dosage, 800 IU/day significantly increased serum 25(OH)D levels (mean difference 13.99 [9.03-18.95]) and reduced the risk of VDD (risk difference -0.21 [-0.32 to -0.10]) compared to 400 IU/day, without increasing the risk of vitamin D excess. The long-term outcomes assessed after 40 weeks' PMA or at follow-up visits showed no significant differences in vitamin D status or neurodevelopmental outcomes between the high-dose and low-dose groups."},{"id":"source_35","type":"source","study":"Effect of vitamin D supplementation during pregnancy and lactation on the development of infants born to Tanzanian women living with HIV: a secondary analysis of a randomised controlled trial","year":2025,"doi":"10.1136/bmjopen-2024-098723","url":"https://doi.org/10.1136/bmjopen-2024-098723","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Infants born to pregnant women living with HIV (WLHIV) are at greater risk for morbidity and mortality and may also have poorer developmental outcomes as compared with infants who are not exposed to HIV. Nutrition interventions in pregnancy may affect developmental outcomes. OBJECTIVES: This study evaluated the effect of maternal vitamin D supplementation on infant development outcomes. DESIGN: We conducted a secondary analysis of a randomised, triple-blind, placebo-controlled trial of maternal vitamin D supplementation from June 2015 to October 2019. SETTING: Antenatal care clinics in Dar es Salaam, Tanzania. PARTICIPANTS: Pregnant WLHIV and their offspring. INTERVENTIONS: Daily 3000 IU vitamin D 3 or placebo supplements taken during pregnancy and lactation. OUTCOME MEASURES: Infants were assessed for cognitive, language and motor development at 1 year of age with the Caregiver Reported Early Development Instruments (CREDI). RESULTS: A total of 2167 infants were eligible, and 1312 of them completed CREDI assessments at 1 year of age. Vitamin D supplementation had no effect on overall CREDI z-scores (standardised mean difference (SMD) 0.03, 95% CI -0.09, 0."},{"id":"source_36","type":"source","study":"Effects of Vitamin D Supplementation on Cardiovascular and Glycemic Biomarkers","year":2021,"doi":"10.1161/JAHA.120.017727","url":"https://doi.org/10.1161/JAHA.120.017727","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Background Experimental and observational studies have suggested a link between vitamin D and cardiovascular and metabolic disease, but this has not been confirmed in randomized controlled trials. We sought to determine whether vitamin D supplementation reduces biomarkers of insulin resistance, inflammation, neurohormonal activation, and lipids. Methods and Results This was a prespecified, secondary analysis of the DAYLIGHT (Vitamin D Therapy in Individuals at High Risk of Hypertension) randomized controlled trial. We measured circulating homeostatic model assessment of insulin resistance, hs-CRP (high-sensitivity C-reactive protein), N-terminal pro-B-type natriuretic peptide, renin, aldosterone, and lipids at baseline and at 6 months in 289 individuals with low vitamin D status (25-hydroxyvitamin-D [25-OH-D] ≤25 ng/mL) receiving low-dose (400 IU/d) versus high-dose (4000 IU/d) vitamin D3 for 6 months. A meta-analysis of randomized controlled trials reporting biomarker changes after vitamin D supplementation was then performed. Levels of 25-OH-D increased in the high-dose relative to the low-dose vitamin D group (+15.5 versus +4.6 ng/mL, P <0.001)."},{"id":"source_37","type":"source","study":"Effects of Whey Protein, Leucine, and Vitamin D Supplementation in Patients with Sarcopenia: A Systematic Review and Meta-Analysis","year":2023,"doi":"10.3390/nu15030521","url":"https://doi.org/10.3390/nu15030521","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"(1) Background: In this study, a meta-analysis was performed to investigate the effects of whey protein, leucine, and vitamin D in sarcopenia; (2) Methods: We searched PubMed, Cochrane Library, Embase, and Scopus databases and retrieved studies published until 5 December 2022. Randomized controlled trials were included to evaluate muscle mass, strength, and function, after using whey protein, leucine, and vitamin D supplementation in patients with sarcopenia; (3) Results: A total of three studies including 637 patients reported the effectiveness of using whey protein, leucine, and vitamin D supplementation in patients with sarcopenia. Without considering whether or not a physical exercise program was combined with nutritional supplementation, no significant differences in grip strength or short physical performance battery (SPPB) scores between the experimental and control groups were noted. However, appendicular muscle mass significantly improved in the experimental group compared to the control group. The results were analyzed according to the presence or absence of a concomitant physical exercise program."},{"id":"source_38","type":"source","study":"Vitamin D supplementation and its impact on leptin and interleukin-6 in women following religious intermittent fasting: a controlled study","year":2025,"doi":"10.3389/fendo.2025.1700844","url":"https://doi.org/10.3389/fendo.2025.1700844","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"BACKGROUND: Vitamin D deficiency is highly prevalent in populations following intermittent or religious fasting, particularly Orthodox nuns with limited sun exposure and dietary restrictions. Vitamin D may modulate adipokines and inflammatory markers, but clinical evidence remains inconsistent. OBJECTIVE: To investigate the effects of vitamin D supplementation on interleukin-6 (IL-6) and leptin concentrations in Orthodox nuns compared with non-supplemented controls. METHODS: In this controlled, non-randomized trial, 33 Orthodox nuns received oral vitamin D 3 supplementation (2,500 IU/day) for 16 weeks, while 42 age-matched women following Orthodox intermittent fasting served as controls. Anthropometric indices and serum concentrations of 25-hydroxyvitamin D [25(OH)D], IL-6, leptin, parathyroid hormone, insulin, and C-reactive protein were measured at baseline and follow-up. RESULTS: At baseline, serum 25(OH)D concentrations were lower in the supplementation group compared with controls (23.4 ± 10.1 vs . 27.7 ± 11.2 ng/mL, p = 0.043). After 16 weeks, 25(OH)D increased significantly in the supplementation group (23.4 ± 10.1 vs . 33.9 ± 11.0 ng/mL, p < 0."},{"id":"source_39","type":"source","study":"Effects of High-Dose Vitamin D Supplementation and Physical Exercise on Vitamin D Metabolites in Professional Football Players: A Pilot Study","year":2026,"doi":"10.3390/nu18010175","url":"https://doi.org/10.3390/nu18010175","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Results : Physical exercise during the football match significantly increased serum concentrations of 25-(OH)D 3 , 24,25-(OH) 2 D 3 , and 3- epi -25-(OH)D 3 (by up to 25%, p < 0.001). The method has satisfactory sensitivity at a limit of quantification (LOQ) of 0.1 ng/mL and appropriate analytical parameters (varying between analytes) including linearity (R2 greater than 0.995) recovery (95-98%), precision (less than 5%) and accuracy (relative bias less than 10%)."},{"id":"source_40","type":"source","study":"A Systematic Review and Meta-Analysis of the Effects of Vitamin D on Systemic Lupus Erythematosus","year":2025,"doi":"10.3390/nu17172794","url":"https://doi.org/10.3390/nu17172794","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"Background and Objective: Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by widespread inflammation and multisystem involvement, leading to substantial morbidity. Given the immunomodulatory role of vitamin D and its association with disease activity in SLE, supplementation has emerged as a potential therapeutic strategy. However, findings across individual studies remain inconsistent, underscoring the need for a systematic review and meta-analysis to synthesize the current evidence on vitamin D supplementation for this disease. Thus, this study aimed to conduct a systematic review and meta-analysis on the effects of vitamin D supplementation on disease activity among patients with SLE. Methods: Systematic searches were carried out in four electronic databases (PubMed, Scopus, Web of Science, and Science Direct) with only studies published after 2013 as a restriction for the search strategy. An assessment of the included studies was conducted according to the recommendations of the Cochrane Handbook for Systematic Reviews of Interventions, using the risk of bias assessment tool in Review Manager (Revman) version 5.3."},{"id":"source_41","type":"source","study":"Different response to vitamin D supplementation in children with RVOT morphology PVCs vs LV fascicular PVCs","year":2026,"doi":"10.1097/MD.0000000000047888","url":"https://doi.org/10.1097/MD.0000000000047888","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Outflow tract premature ventricular contractions (PVCs) are typically benign arrhythmias in structurally normal hearts. Vitamin D insufficiency has been shown to cause PVCs in both children and adults. This study examined the impact of vitamin D supplementation in children with an increased burden of PVCs in 2 patient categories with distinct electrocardiogram morphologies: right ventricular outflow tract (RVOT) and left fascicular. We enrolled 46 patients (mean age 10.6 ± 4.1 years, 26% female) showing an increased burden of monomorphic PVCs (mean = 18,925/24 hours) and vitamin D deficiency. We compared 36 patients with RVOT morphology and 10 patients with left ventricular fascicular morphology. In the RVOT morphology group, the mean age was 12.7 ± 2.7 years, comprising 75% males and 25 females, with a PVC burden of 18,343.7 ± 13,836.2/24 hours and a 25-OH vitamin D level of 23.5 ± 9.4 ng/mL. After 2 months of oral vitamin D supplementation, the vitamin D level increased to 41.6 ± 6.3, followed by a considerable reduction in PVC burden to 3628.0 ± 2347.2. This group of children showed 80% reduction in PVC burden."},{"id":"source_42","type":"source","study":"The health outcomes of vitamin D supplementation in Africa: a systematic review and meta-analysis","year":2025,"doi":"10.1186/s40795-025-01046-w","url":"https://doi.org/10.1186/s40795-025-01046-w","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Vitamin D supplementation is essential for health, yet its full benefits and optimal use remain incompletely understood, particularly given the global prevalence of deficiency, which affects around 50% of the population, with higher rates in high-latitude regions and among individuals with darker skin. This systematic review synthesizes evidence on the health outcomes of vitamin D supplementation in Africa, addressing gaps in regional and demographic-specific research. METHODS: A comprehensive literature search was conducted using PubMed, Scopus, Epistemonikos, and Google Scholar, limited to English-language publications without date restrictions. Two independent reviewers evaluated study eligibility, data quality, and risk of bias. The findings were reported in accordance with PRISMA guidelines, employing narrative synthesis and meta-analyses to compare the effects of vitamin D supplementation against control groups. Heterogeneity and publication bias were assessed using Egger's regression and Q statistics. RESULTS: The review included 14 randomized controlled trials from 9 African countries, involving 11,259 participants."},{"id":"source_43","type":"source","study":"Inappropriate vitamin D supplementation among multimorbid older patients: a multicountry analysis","year":2025,"doi":"10.1186/s12877-025-06189-w","url":"https://doi.org/10.1186/s12877-025-06189-w","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"BACKGROUND: The prevalence of vitamin D supplementation and the percentage of participants with a lack of appropriate vitamin D supplementation (\"potential underuse\") or potentially inappropriate vitamin D supplementation (\"potential overuse\") and risk factors for these are currently unclear. METHODS: Cross-sectional analysis from the OPERAM study, a multicenter cluster randomized controlled trial in four European countries (Belgium, Ireland, The Netherlands, Switzerland) including multimorbid (≥ 3 chronic conditions) older patients, with polypharmacy (≥ 5 chronic medications). For the definition of potential underuse and overuse we used high-risk conditions, which were defined according to the START criteria (version 2) for potential prescribing omissions in older people i.e., E2) long-term systemic corticosteroid therapy, known osteoporosis or osteopenia, E3) previous fragility fractures, and E5) housebound/in nursing homes or experiencing falls. We used mixed effect logistic regression to identify factors associated with underuse and overuse. RESULTS: 2008 patients (79.4y, SD 6.3, 45% female) were included. 825/2008 (41.1%) were supplemented with vitamin D."},{"id":"source_44","type":"source","study":"Effects of Resistance Training Combined with Vitamin D Supplementation on Health-Related Variables in the Elderly: Muscle Strength, Body Composition, and Inflammatory Status","year":2025,"doi":"10.3390/ijerph22111695","url":"https://doi.org/10.3390/ijerph22111695","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Aging is associated with changes in body composition that lead to low-grade chronic inflammation, compromising the health of the elderly. This condition can be mitigated by resistance training (RT) and vitamin D supplementation, promoting the health of this population. This study aimed to investigate the effects of 12 weeks of RT combined with vitamin D supplementation on body composition, muscle strength, and inflammatory status in older adults. A total of 26 participants were randomly assigned to an Experimental Group (EG: n = 12; 11 Female; 70.6 ± 4.7 years; RT + 2000 IU/day of vitamin D) and a Control Group (EG: n = 14; 11 Female; 69.6 ± 4.6 years; RT + placebo). Both groups performed the same RT program (8 exercises; 2 sets; 10 RM, twice per week). Before and after the intervention, participants were assessed using DEXA, strength tests (sit-to-stand test and handgrip strength), and serum biomarkers (IL-6, TNF-α, 25(OH)D). Both groups showed significant strength gains, particularly in the lower limbs ( p < 0.05 for all tests and groups), with no between-group differences in body composition or inflammatory markers ( p > 0.05 for all tests and groups)."},{"id":"source_45","type":"source","study":"Effects of Combined Exercise and Calcium/Vitamin D Supplementation on Bone Mineral Density in Postmenopausal Women: A Systematic Review and Meta-Analysis","year":2025,"doi":"10.3390/nu17243866","url":"https://doi.org/10.3390/nu17243866","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"Compared with calcium and vitamin D supplementation alone, combined interventions significantly increased lumbar spine (SMD = 0.31, 95% CI [0.06, 0.55]) and femoral neck BMD (SMD = 0.47, 95% CI [0.09, 0.84]), with consistent but nonsignificant trends at other skeletal sites. Shorter interventions (≤6 months) yielded greater gains in BMD, whereas longer durations provided no additional advantage."},{"id":"source_46","type":"source","study":"Efficacy of vitamin D supplementation on depressive symptoms in older patients: a meta-analysis of randomized controlled trials","year":2024,"doi":"10.3389/fmed.2024.1467234","url":"https://doi.org/10.3389/fmed.2024.1467234","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: The relationship between vitamin D and depression has garnered significant attention in recent years. However, the efficacy of vitamin D in ameliorating depression among specific subgroups of older patients remains controversial. This study aimed to assess the impact of vitamin D supplementation on depressive symptoms and the prevalence of depression in older adults. Additionally, the study sought to examine potential moderating factors, including differences among population subgroups and various supplementation strategies. METHODS: A systematic literature search was conducted in the databases PubMed, EMBASE, Web of Science, and the Cochrane Library up to March 2024. The RevMan 5.3 software was utilized to calculate the standardized mean difference (SMD) and to evaluate the quality of evidence using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. The objective was to determine the efficacy of vitamin D supplementation in alleviating depressive symptoms or treating depression in older adults. RESULTS: This meta-analysis encompassed eleven studies, comprising a total of 21,561 participants."},{"id":"source_47","type":"source","study":"Efficacy of vitamin D supplementation in patients diagnosed with depression: a dose–response meta-analysis of randomized controlled trials","year":2026,"doi":"10.3389/fnut.2026.1772451","url":"https://doi.org/10.3389/fnut.2026.1772451","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"BACKGROUND: Depression affects 5% of the global population, posing significant health and economic challenges. OBJECTIVES: This study evaluates the efficacy of vitamin D supplementation in reducing depressive symptoms and explores its dose-response relationship. METHODS: We used PubMed, EMBASE, and Cochrane Library to identify randomized controlled trials using the keyword combination of vitamin D and depression from inception to June 2024. The primary outcome was the change in depressive symptoms. A dose-response meta-analysis using restricted cubic splines was conducted to explore potential sources of heterogeneity and examine the dose-response relationship. RESULTS: The outcomes were reported in 15 studies encompassing data from 962 participants. Vitamin D supplementation demonstrated a significant improvement in depressive symptoms compared to the placebo group (SMD: -0.98; 95% CI - 1.28 to -0.68; p < 0.001). Statistical heterogeneity was high ( I 2 = 79%; p < 0.001). Secondary outcomes revealed significant reductions in serum PTH (MD: -4.19; 95% CI - 8.18 to -0.2 pg./mL) and TNFα levels (MD: -0.3; 95% CI - 0.44 to -0.16 pg."},{"id":"source_48","type":"source","study":"Vitamin D supplementation for managing COVID-19 in patients with vitamin D deficiency: a systematic review and meta-analysis of randomised controlled trials","year":2025,"doi":"10.1136/bmjopen-2024-091903","url":"https://doi.org/10.1136/bmjopen-2024-091903","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVES: Vitamin D deficiency is prevalent among the population. Previous studies have shown that vitamin D supplementation might be useful for treating COVID-19 infection. Therefore, we performed a meta-analysis to explore vitamin D supplementation efficacy in treating COVID-19 patients with vitamin D deficiency. DESIGN: Systematic review and meta-analysis DATA SOURCES: PubMed, Cochrane Library, Embase and Web of Science. ELIGIBILITY CRITERIA: Randomised controlled trials exploring vitamin D supplementation for patients with COVID-19 and vitamin D deficiency. DATA EXTRACTION AND SYNTHESIS: Two independent reviewers employed standardised methods to search, screen and code the included studies. The primary outcomes included mortality during follow-up, 28-day mortality, need for mechanical ventilation and intensive care unit (ICU). The secondary outcome included length of stay in hospital and ICU. The risk of bias was assessed using the Risk of Bias 2 tool. Depending on the level of heterogeneity, either a random-effects model or a fixed-effects model was applied."},{"id":"source_49","type":"source","study":"Impact of vitamin D supplementation on post-stroke rehabilitation outcomes: A systematic review and meta-analysis","year":2025,"doi":"10.52225/narra.v5i2.1848","url":"https://doi.org/10.52225/narra.v5i2.1848","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"Each year, there are approximately 12.2 million new stroke cases and 6.5 million stroke-related deaths, with low- and middle-income countries shouldering a disproportionately high financial burden. Studies have associated vitamin D deficiency with arteriosclerosis, left ventricular hypertrophy, and vascular dysfunction, contributing to an elevated risk of stroke. The aim of this study was to evaluate how vitamin D supplementation affects post-stroke outcomes. A comprehensive literature search was performed across PubMed, Scopus, the Cochrane Library, ScienceDirect, Springer Link, ProQuest, and Epistemonikos from April to May 2024. This study focused on comparing the efficacy of vitamin D supplementation versus no supplementation in stroke patients of all ages. Outcome measures included the Functional Ambulation Classification (FAC), Brunnstrom Recovery Stage (BRS), Modified Rankin Scale (mRS), and National Institutes of Health Stroke Scale (NIHSS). Case reports, reviews, and research on other cardiovascular or metabolic issues were excluded. Five authors extracted data and analyzed bias separately using the Risk of Bias Version 2 (RoB V2) algorithms."},{"id":"source_50","type":"source","study":"The Association Between Vitamin D and Polycystic Ovary Syndrome (PCOS) in Women: A Systematic Review","year":2026,"doi":"10.3390/nu18060968","url":"https://doi.org/10.3390/nu18060968","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"Background/Objectives : Polycystic ovary syndrome (PCOS) is a prevalent endocrine disorder characterized by reproductive and metabolic dysfunction. Vitamin D deficiency is common in women with PCOS and is linked to adverse metabolic and reproductive outcomes. However, the role of vitamin D supplementation in managing PCOS remains unclear due to the heterogeneous evidence available. This systematic review aimed to synthesize both observational and interventional studies to assess the association between vitamin D levels and PCOS, focusing on prevalence, metabolic outcomes, and reproductive parameters. Methods : A comprehensive search of PubMed, Web of Science, Scopus, and Embase was conducted in October 2025, identifying studies published between January 2000 and October 2025. Eligible studies included observational studies and randomized controlled trials (RCTs) evaluating serum 25-hydroxyvitamin D [25(OH)D] levels and/or the effects of vitamin D supplementation in women with PCOS. Studies were included if they used recognized diagnostic criteria for PCOS or sufficient diagnostic details to confirm the condition."},{"id":"source_51","type":"source","study":"Effects of Exercise Alone or Combined With Cognitive Training and Vitamin D Supplementation to Improve Cognition in Adults With Mild Cognitive Impairment","year":2023,"doi":"10.1001/jamanetworkopen.2023.24465","url":"https://doi.org/10.1001/jamanetworkopen.2023.24465","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"IMPORTANCE: Exercise, cognitive training, and vitamin D may enhance cognition in older adults with mild cognitive impairment (MCI). OBJECTIVE: To determine whether aerobic-resistance exercises would improve cognition relative to an active control and if a multidomain intervention including exercises, computerized cognitive training, and vitamin D supplementation would show greater improvements than exercise alone. DESIGN, SETTING, AND PARTICIPANTS: This randomized clinical trial (the SYNERGIC Study) was a multisite, double-masked, fractional factorial trial that evaluated the effects of aerobic-resistance exercise, computerized cognitive training, and vitamin D on cognition. Eligible participants were between ages 65 and 84 years with MCI enrolled from September 19, 2016, to April 7, 2020. Data were analyzed from February 2021 to December 2022."},{"id":"source_52","type":"source","study":"Vitamin D supplementation for tuberculosis prevention: A meta-analysis","year":2025,"doi":"10.17305/bb.2025.12527","url":"https://doi.org/10.17305/bb.2025.12527","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"Vitamin D plays an important role in immune regulation, prompting interest in its potential for preventing tuberculosis. However, clinical findings regarding its protective effects against tuberculosis infection and disease remain inconsistent. We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to assess the impact of vitamin D supplementation on the prevention of tuberculosis infection and the progression to active tuberculosis. We searched PubMed, Embase, Cochrane Library, and Web of Science databases through January 2025. Eligible studies involved participants without active tuberculosis at baseline and reported outcomes related to tuberculosis. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using a random-effects model. Subgroup and sensitivity analyses were conducted, and the certainty of evidence was evaluated using the GRADE approach. Six RCTs, involving 15,677 participants, met our inclusion criteria. Compared to placebo, vitamin D supplementation did not significantly reduce the risk of tuberculosis infection (5 RCTs; OR: 0.95; 95% CI: 0.79-1.14; p = 0."},{"id":"source_53","type":"source","study":"Vitamin D and calcium supplementation in women undergoing pharmacological management for postmenopausal osteoporosis: a level I of evidence systematic review","year":2025,"doi":"10.1186/s40001-025-02412-x","url":"https://doi.org/10.1186/s40001-025-02412-x","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"The present systematic review investigates whether different doses of vitamin D and calcium supplementation in women with postmenopausal osteoporosis undergoing antiresorptive therapy have an association with BMD (spine, hip, femur neck), serum markers of osteoporosis (bone-ALP, NTX, CTX), the rate of pathological vertebral and non-vertebral fractures, adverse events, and mortality. This systematic review was conducted according to the PRISMA 2020 guidelines. PubMed, Google Scholar, Embase, and Scopus databases were accessed in September 2024. All randomised clinical trials (RCTs) comparing two or more treatments for postmenopausal osteoporosis supplemented with vitamin D and/or calcium were accessed. Only studies that indicated daily vitamin D and/or calcium supplementation doses were accessed. Data from 37 RCTs (43,397 patients) were retrieved. Patients received a mean of 833.6 ± 224.0 mg and 92.8 ± 228.7 UI of calcium and vitamin D supplementation, respectively. The mean length of the follow-up was 25.8 ± 13.3 months. The mean age of the patients was 66.4 ± 5.6 years, and the mean BMI was 25.2 ± 1.6 kg/m 2 ."},{"id":"source_54","type":"source","study":"Vitamin D supplementation in later life: a systematic review of efficacy and safety in movement disorders","year":2024,"doi":"10.3389/fnagi.2024.1333217","url":"https://doi.org/10.3389/fnagi.2024.1333217","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"INTRODUCTION: Nutrition plays a pivotal role in the multidisciplinary approach to rehabilitating middle to old-aged patients with neurological diseases including movement disorders (MDs). Despite the prevalence of vitamin D deficiency in many patients with MDs, data supporting supplementation's effectiveness and safety is sparse and conflicting, therefore, our explicit objective was to provide an all-encompassing review of the subject. METHODS: A comprehensive search of PubMed, Embase, and other scientific databases was conducted up to November 1 2023. The searches included RCTs in all languages with human participants aged 35 and above and not meeting these requirements led to exclusion. RESULTS: Four studies on Parkinson's disease (PD) and one on restless legs syndrome (RLS) including 369 MD patients, however, none in a rehabilitation context, were found. Although three of the four PD studies showed better outcomes, such as decreasing levodopa-induced dyskinesia or enhancing physical performance in some or all domains, the RLS study did not identify symptom improvement."},{"id":"source_55","type":"source","study":"Effect of vitamin D supplementation on motor symptoms in Parkinson’s disease: a meta-analysis of randomized controlled trials","year":2025,"doi":"10.3389/fnut.2025.1500875","url":"https://doi.org/10.3389/fnut.2025.1500875","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"INTRODUCTION: Lower serum vitamin D levels may associate with higher motor symptom severity in Parkinson's disease (PD). This study aimed to test the efficacy of supplemental vitamin D on ameliorating motor symptoms in PD, which is the most comprehensive study to assess the relationship between vitamin D supplementation and PD motor symptoms to date. METHODS: An electronic literature search supplemented by hand searching up to Sep 2024 identified 8 randomized controlled trials involving 646 cases of PD. Weighted mean difference (WMD) and 95% confidence interval (CI) of PD were assessed through pooling the collected data from eligible studies using Stata software. RESULTS: The results indicated that supplemental vitamin D did not reduce the Unified Parkinson's Disease Rating Scale part III score (WMD=-0.56, 95% CI=[-2.34, 1.23]), 10/8 m walk test time (WMD=0.59, 95% CI=[-0.46, 1.64]) and timed up and go (TUG) test time (WMD=-0.57, 95% CI=[-1.45, 0.31]). A statistically significant benefit of supplemental vitamin D was observed on 6-Minute walking test distance (WMD=24.85, 95% CI=[6.54, 43.16])."},{"id":"source_56","type":"source","study":"Can Vitamin D supplementation enhance the effectiveness of exercise-induced weight loss in overweight or obese adults? Evidence from integrated transcriptomic and meta-analysis","year":2025,"doi":"10.3389/fnut.2025.1664960","url":"https://doi.org/10.3389/fnut.2025.1664960","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVE: Obesity is a major global public health challenge, and Vitamin D deficiency is prevalent among obese individuals. This study aimed to evaluate whether Vitamin D supplementation enhances the effectiveness of exercise-induced weight loss in overweight or obese adults by integrating transcriptomic analysis and meta-analysis. METHODS: Transcriptomic data from the GEO and GTEx databases were integrated for differential gene expression analysis, Gene Ontology (GO)/Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment, and Gene Set Enrichment Analysis (GSEA). Currently, clinical transcriptomic data regarding the effect of Vitamin D on exercise intervention outcomes in overweight/obese adults is limited. To address this gap, this study utilized cold-induced skeletal muscle shivering as a surrogate model to explore its potential molecular mechanisms. A meta-analysis of eight randomized controlled trials (RCT) involving 481 participants, was conducted to assess the combined effects of exercise and Vitamin D supplementation on body composition and metabolic parameters, with subgroup analyses by age and exercise type."},{"id":"source_57","type":"source","study":"Does Vitamin D Supplementation Impact Fibromyalgia-Related Pain? A Systematic Review and Meta-Analysis","year":2025,"doi":"10.3390/nu17203232","url":"https://doi.org/10.3390/nu17203232","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"Background: Fibromyalgia is a chronic condition characterized by widespread pain, fatigue, and localized tenderness. Its pathophysiology remains unclear, and treatment options are often limited and only partially effective. Recent studies suggest a potential link between vitamin D deficiency and symptom severity, as vitamin D may play a role in modulating pain and inflammation. Methods: This systematic review and meta-analysis assessed the efficacy of vitamin D supplementation in reducing pain and improving quality of life in fibromyalgia patients, focusing on studies up to 31 December 2024. Following PRISMA guidelines, a literature search in PubMed, Web of Science, and Scopus identified 2776 articles; 7 were included in the systematic review and 4 studies in each meta-analysis. Results: Results showed that vitamin D supplementation significantly reduced pain levels compared to the control group, with a statistically significant effect observed using the NRS or VAS (SMD = -0.85; 95% CI: -1.54 to -0.17; p = 0.0148), as well as the FIQ scale (SMD = -0.87; 95% CI: -1.56 to -0.20; p = 0.0115), resulting in an improvement in quality of life."},{"id":"source_58","type":"source","study":"Effects of whey protein plus vitamin D supplementation combined with progressive resistance training on glycaemic control, body composition, muscle function and cardiometabolic risk factors in middle-aged and older overweight/obese adults with type 2 diabetes: A 24-week randomized controlled trial.","year":2021,"doi":"10.1111/dom.14299","url":"https://doi.org/10.1111/dom.14299","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"AIM: To determine the effect of whey protein plus vitamin D supplementation combined with progressive resistance training (PRT) on glycaemic control, body composition, muscle function and cardiometabolic risk factors in middle-aged and older adults with type 2 diabetes (T2D). MATERIALS AND METHODS: In this 24-week, randomized controlled trial, 198 overweight/obese adults (aged 50-75 years) with T2D undertook PRT (2-3 days/week) with random allocation to whey protein (20 g each morning plus 20 g postexercise) plus vitamin D 3 (2000 IU/day) (PRT + ProD, n = 98) or no supplementation (PRT, n = 100). Primary outcomes were HbA1c and homeostatic model assessment-2 of insulin resistance (HOMA2-IR). Secondary endpoints included fasting plasma glucose (FPG), body composition, muscle strength, physical function, blood pressure, blood lipids and inflammatory markers. RESULTS: At 24 weeks, supplementation did not enhance the effects of PRT on HbA1c (mean absolute change: PRT + ProD -0.10% [95% CI, -0.24%, 0.05%] vs. PRT -0.17% [95% CI, -0.32%, -0.03%], p = .322) or HOMA2-IR (PRT + ProD -0.12 [95% CI, -0.27, 0.03] vs. PRT -0.03 [95% CI, -0.14, 0.09], p = .370)."},{"id":"source_59","type":"source","study":"The Role of Vitamin D Supplementation in Enhancing Muscle Strength Post-Surgery: A Systemic Review","year":2025,"doi":"10.3390/nu17091512","url":"https://doi.org/10.3390/nu17091512","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Background : Vitamin D is vital for musculoskeletal health, with emerging evidence highlighting its role in muscle function. While its preoperative and postoperative benefits for bone health are well documented, the effect of vitamin D supplementation on post-surgical muscle recovery remains underexplored. This systematic review consolidates current evidence on the impact of vitamin D supplementation in enhancing muscle strength following surgery. Methods : This review adhered to PRISMA guidelines and was registered on PROSPERO. A systematic search of PubMed, EMBASE, and Cochrane databases was conducted, covering articles from inception to 15 January 2025. Studies evaluating the effect of vitamin D supplementation on muscle strength in surgical contexts were included. Data extraction focused on study design, population demographics, vitamin D dosage, timing, and measured outcomes. A narrative synthesis was performed due to heterogeneity in study designs and outcomes. Results : From 701 initial records, 10 studies met the inclusion criteria."},{"id":"source_60","type":"source","study":"Vitamin D Supplementation Improves Cognitive Function Through Reducing Oxidative Stress Regulated by Telomere Length in Older Adults with Mild Cognitive Impairment: A 12-Month Randomized Controlled Trial.","year":2020,"doi":"10.3233/jad-200926","url":"https://doi.org/10.3233/jad-200926","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"BACKGROUND: Cognitive decline in older adults is a serious public health problem today. Association between vitamin D supplementation and cognition remains controversial. OBJECTIVE: To determine whether a 12-month vitamin D supplementation improves cognitive function in elderly subjects with mild cognitive impairment (MCI), and whether it is mediated through the mechanism in which telomere length (TL) regulate oxidative stress. METHODS: This was a double-blind, randomized, placebo-controlled trial in Tianjin, China. Participants were all native Chinese speakers aged 65 years and older with MCI. 183 subjects were randomized to an intervention group (vitamin D 800 IU/day, n = 93) or a placebo group (the matching starch granules, n = 90), and followed up for 12 months. Tests of cognitive function and mechanism-related biomarkers were evaluated at baseline, 6 months, and 12 months. RESULTS: Repeated-measures ANOVA showed substantial improvements in the full scale intelligence quotient (FSIQ), information, digit span, vocabulary, block design, and picture arrangement scores in the vitamin D group over the placebo group (p < 0.001)."},{"id":"source_61","type":"source","study":"The Effects of Vitamin D Supplementation on Biomarkers of Inflammation and Oxidative Stress Among Women with Polycystic Ovary Syndrome: A Systematic Review and Meta-Analysis of Randomized Controlled Trials","year":2018,"doi":"10.1055/s-0044-101355","url":"https://doi.org/10.1055/s-0044-101355","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"The current systematic review and meta-analysis of randomized controlled trials (RCTs) was conducted to summarize the effect of vitamin D supplementation on biomarkers of inflammation and oxidative stress among women with polycystic ovary syndrome (PCOS). Cochrane library, Embase, PubMed, and Web of Science database were searched to identify related randomized-controlled articles (RCTs) published up to November 2017. Two researchers assessed study eligibility, extracted data, and evaluated risk of bias of included RCTs, independently. To check heterogeneity Q-test and I 2 statistics were used. Data were pooled by using the random-effect model and standardized mean difference (SMD) was considered as summary effect size. Seven RCTs were included into our meta-analysis. The findings showed that vitamin D supplementation in women with PCOS significantly decreased high-sensitivity C-reactive protein (hs-CRP) (SMD -1.03; 95% CI, -1.58, -0.49; p <0.001) and malondialdehyde (MDA) (SMD -1.64, 95% CI -2.26 to -1.02, p <0.001), and significantly increased total antioxidant capacity (TAC) levels (SMD 0.86, 95% CI 0.08 to 1.64, p=0.03)."},{"id":"source_62","type":"source","study":"Effects of Vitamin D Supplementation on Strength, Physical Function, and Health Perception in Older, Community‐Dwelling Men","year":2003,"doi":"10.1046/j.1532-5415.2003.51561.x","url":"https://doi.org/10.1046/j.1532-5415.2003.51561.x","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"review-level","excerpt":"OBJECTIVES: To study the effects of vitamin D supplementation in healthier populations of men. DESIGN: : Randomized, controlled trial. SETTING: General clinical research center. PARTICIPANTS: Sixty-five healthy, community-dwelling men (mean age+/-standard deviation=76+/-4, range 65-87). INTERVENTION: Cholecalciferol (1,000 IU/d) or placebo supplementation for 6 months; all received 500 mg supplemental calcium. MEASUREMENTS: Upper and lower extremity muscle strength and power, physical performance and activity, health perception, calcium and vitamin D intake, and biochemical assessment, including 25-hydroxyvitamin D (25OHD), parathyroid hormone (PTH), and ionized calcium levels. RESULTS: The levels of 25OHD increased and PTH decreased in the cholecalciferol group, whereas there were no significant changes in the control group (P<.001). Baseline 25OHD levels correlated with baseline single-leg stance time and physical activity score. Baseline PTH levels correlated with baseline 8-foot walk time and physical activity score. No significant difference in strength, power, physical performance, or health perception was found between groups."}],"edges":[{"from":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","to":"claim_1","type":"contains_claim"},{"from":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","to":"claim_2","type":"contains_claim"},{"from":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","to":"claim_3","type":"contains_claim"},{"from":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","to":"claim_4","type":"contains_claim"},{"from":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","to":"claim_5","type":"contains_claim"},{"from":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","to":"claim_6","type":"contains_claim"},{"from":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","to":"claim_7","type":"contains_claim"},{"from":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","to":"claim_8","type":"contains_claim"},{"from":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","to":"claim_9","type":"contains_claim"},{"from":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","to":"claim_10","type":"contains_claim"},{"from":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","to":"claim_11","type":"contains_claim"},{"from":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","to":"claim_12","type":"contains_claim"},{"from":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","to":"claim_13","type":"contains_claim"},{"from":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","to":"claim_14","type":"contains_claim"},{"from":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","to":"claim_15","type":"contains_claim"},{"from":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","to":"claim_16","type":"contains_claim"},{"from":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","to":"claim_17","type":"contains_claim"},{"from":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","to":"claim_18","type":"contains_claim"},{"from":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","to":"claim_19","type":"contains_claim"},{"from":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","to":"claim_20","type":"contains_claim"},{"from":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","to":"claim_21","type":"contains_claim"},{"from":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","to":"claim_22","type":"contains_claim"},{"from":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","to":"claim_23","type":"contains_claim"},{"from":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","to":"claim_24","type":"contains_claim"},{"from":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","to":"claim_25","type":"contains_claim"},{"from":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","to":"claim_26","type":"contains_claim"},{"from":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","to":"claim_27","type":"contains_claim"},{"from":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","to":"claim_28","type":"contains_claim"},{"from":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","to":"claim_29","type":"contains_claim"},{"from":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","to":"claim_30","type":"contains_claim"}],"screening":{"identified":62,"screened":62,"excluded":0,"included":62,"included_or_retained":62,"flow":["identified","screened","excluded_with_reasons","included"],"wording":"62 candidate receipts retained after source retrieval, deduplication, and topic filtering. This is an evidence-map screening trace, not a PRISMA full-text exclusion audit.","exclusion_reasons":["No PRISMA full-text exclusion-stage filter was applied."]}}},{"name":"contradiction_map.json","media_type":"application/json","content":{"publication_id":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","screening":{"identified":62,"screened":62,"excluded":0,"included":62,"included_or_retained":62,"flow":["identified","screened","excluded_with_reasons","included"],"wording":"62 candidate receipts retained after source retrieval, deduplication, and topic filtering. This is an evidence-map screening trace, not a PRISMA full-text exclusion audit.","exclusion_reasons":["No PRISMA full-text exclusion-stage filter was applied."]},"limitations":["This is an agent-assisted evidence map, not a PRISMA-complete systematic review or clinical guideline.","It is not PROSPERO-registered and should not be read as medical advice.","Public sidecars expose citation traces and extraction status; empty fields mean not extracted, not assumed absent."],"contradictions":["Evidence-honesty note: 58/62 retained sources are indirect, review-level, adjacent, or mechanistic and are used only to bound interpretation. The conclusion therefore does not support broad causal, clinical, or policy claims. Vitamin D supplementation is among the most widely prescribed interventions worldwide, yet its clinical benefits beyond correcting deficiency remain contentious across cardiometabolic, musculoskeletal, immune, and longevity outcomes. This synthesis applies a structured, AI-assisted evidence appraisal with documented audit trails to systematically evaluate effect directions and statistical signals across 62 curated reference papers spanning randomized trials, observational cohorts, and meta-analyses. For immune and inflammatory markers, vitamin D supplementation in women with PCOS significantly reduced inflammatory biomarkers (P < 0.001) (Akbari 2018), yet a separate meta-analysis of obese or overweight populations reported mixed findings on co-supplementation with magnesium (Deng 2025). Overall, the evidence supports that vitamin D supplementation reliably raises serum 25(OH)D and may offer modest mortality or inflammatory benefits in specific clinical contexts, but effects on cardiometabolic hard endpoints, musculoskeletal function, and frailty prevention remain insufficiently suggested by current human RCTs.","Overall, the evidence supports that vitamin D supplementation reliably raises serum 25(OH)D and may offer modest mortality or inflammatory benefits in specific clinical contexts, but effects on cardiometabolic hard endpoints, musculoskeletal function, and frailty prevention remain insufficiently suggested by current human RCTs.","Aging populations worldwide face a growing burden of chronic disease, functional decline, and reduced healthspan, creating urgent interest in interventions that might modify the trajectory of age-related deterioration. Vitamin D supplementation effects have emerged as a particularly compelling area of investigation, given that vitamin D deficiency is highly prevalent among older adults and has been associated with numerous adverse health outcomes. The question of whether correcting this deficiency through supplementation can meaningfully extend healthspan or lifespan remains one of the most actively debated topics in preventive medicine. Epidemiological studies have consistently linked low serum 25-hydroxyvitamin D levels with increased mortality, cardiovascular disease, diabetes, and cancer, yet the causal direction of these associations has been difficult to establish. With hundreds of millions of adults worldwide taking vitamin D supplements, often without clear clinical indication, understanding the true scope of vitamin D supplementation effects has significant public health implications. The stakes are considerable: if vitamin D supplementation effects genuinely extend healthspan, the intervention would be remarkably accessible and cost-effective; if the effects are illusory or harmful at certain doses, current supplementation practices may represent a significant misallocation of healthcare resources.","The geroscience hypothesis proposes that targeting fundamental aging biology — rather than individual diseases one at a time — could delay or prevent multiple age-related conditions simultaneously. This framework has generated enormous enthusiasm for repurposing existing medications and supplements as potential geroprotectors, given the prohibitive cost and timeline of de novo drug development. Vitamin D supplementation effects sit at the intersection of this repurposing logic and basic biology: vitamin D receptors are expressed in virtually every tissue, and the secosteroid hormone influences cellular processes ranging from calcium homeostasis to immune regulation to gene transcription. The biological plausibility for vitamin D supplementation effects extending healthspan is substantial, as vitamin D signaling modulates pathways implicated in cellular senescence, chronic inflammation, and mitochondrial function. However, biological plausibility alone does not constitute clinical evidence, and the geroscience field has learned caution from other repurposed compounds — such as metformin or rapamycin — where mechanistic promise has not consistently translated to human outcomes. The critical question for vitamin D supplementation effects is whether the intervention modifies aging biology in humans at achievable doses, or whether observational associations merely reflect reverse causation, confounding by health status, or residual confounding by outdoor activity and sunlight exposure. Establishing this distinction requires careful examination of the randomized controlled trial evidence, which this synthesis undertakes systematically.","Several unresolved questions pervade the literature on vitamin D supplementation effects, creating persistent uncertainty about clinical applicability. First, the dose-response relationship remains poorly characterized: some meta-analyses suggest benefits only at higher doses or in deficient populations, while others find no clear dose-response gradient. Second, the translation from mechanistic plausibility to clinical function is incomplete — for example, vitamin D supplementation effects on inflammatory markers such as C-reactive protein do not reliably predict improvements in hard outcomes. Third, population specificity appears critical, as vitamin D supplementation effects may differ substantially between those with documented deficiency versus sufficiency, between older and younger adults, and across racial and ethnic groups with varying baseline vitamin D status. Fourth, the question of optimal treatment duration remains unanswered, with trial durations ranging from weeks to years and no consensus on whether long-term continuous supplementation confers additional benefit or risk. Fifth, genetic polymorphisms in the vitamin D receptor may modify vitamin D supplementation effects, as suggested by recent pharmacogenomic analyses, but this evidence remains preliminary. Sixth, potential harms at high doses — including hypercalcemia, kidney stones, and vascular calcification — are often inadequately captured in trials designed to detect benefits rather than harms.","Preclinical and disease-model studies provide the mechanistic substrate for the vitamin D supplementation effects hypothesis, and the corpus under review spans cell-culture, rodent, and human tissue investigations that collectively implicate vitamin D in inflammation, metabolic regulation, and cellular resilience. The mechanistic plausibility of vitamin D as a modulator of mitochondrial function and oxidative stress is further supported by a randomized controlled trial showing that vitamin D supplementation improves cognitive function through reducing oxidative stress regulated by telomere length in older adults with mild cognitive impairment (Yang 2020, 12-month RCT). Collectively, these preclinical and mechanistic data establish that vitamin D supplementation effects on inflammation, insulin signaling, and cellular stress are biologically plausible, yet the pathway-level evidence does not consistently translate into disease-level outcomes, a disjunction that frames the clinical-trial literature reviewed below.","Contextual Adjacent Evidence: n=3; claims=159; mixed signal in 2/3 sources | directness: 3 review; main limitation: no direct clinical anchor.","The evidence base for vitamin D supplementation and cardiometabolic endpoints includes a large randomized trial, a mechanistic RCT, and two systematic reviews. Peng 2025 performed an integrated transcriptomic and meta-analysis focusing on overweight or obese adults (BMI ≥ 25 kg/m²), while Migliorini 2025 provided a level I systematic review of vitamin D and calcium in women with postmenopausal osteoporosis.","Mechanistically, vitamin D is hypothesized to influence cardiometabolic risk through effects on insulin sensitivity, inflammatory pathways, and adipocyte differentiation. Miller 2021 tested this pathway by combining vitamin D with whey protein and resistance training, targeting both glycemic control and cardiometabolic risk factors directly. Peng 2025 used transcriptomic integration to explore whether vitamin D potentiates exercise-induced metabolic changes in overweight individuals, addressing a complementary mechanistic question. The observational and review-level data from Tobias 2025 and Migliorini 2025, however, provide only indirect evidence on these pathways, as neither design isolates the causal contribution of vitamin D from confounded dietary or behavioral patterns.","Within the corpus, the direction of evidence shows notable tension. Miller 2021 and Peng 2025 also returned unclear effect directions, reflecting the complexity of multi-component interventions and integrated analytic approaches that make it difficult to attribute outcomes specifically to vitamin D. This pattern — mechanistic plausibility coexisting with mixed or null human RCT evidence — is consistent with the broader synthesis that the cardiometabolic anti-aging case for vitamin D supplementation remains incomplete, and boundary conditions regarding dose, population, and co-intervention require further delineation.","The synthesized evidence base for vitamin D supplementation on contextual outcomes encompasses systematic reviews and meta-analyses addressing distinct clinical populations, including community-dwelling older adults at risk for sarcopenia, patients with systemic lupus erythematosus (SLE), and women with polycystic ovary syndrome (PCOS). Prokopidis 2022 conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) evaluating vitamin D monotherapy versus placebo on indices of sarcopenia in older adults. In parallel, Kababi 2025 synthesized twelve studies reporting positive associations between vitamin D supplementation and reduced disease activity in SLE, while Jaafar 2026 reviewed observational data indicating a high prevalence of vitamin D deficiency in women with PCOS. Together, these reviews form the evidentiary framework for understanding vitamin D's role beyond skeletal health.","Mechanistically, the disparity between null findings in sarcopenia trials and positive signals in autoimmune and endocrine contexts may reflect differences in disease-specific pathways. Vitamin D's immunomodulatory properties, including regulation of T-cell differentiation and cytokine production, provide a plausible biological substrate for the disease activity reductions observed in SLE (Kababi 2025). In PCOS, the high prevalence of deficiency documented by Jaafar 2026 may implicate vitamin D in insulin signaling and ovarian steroidogenesis pathways. Preclinical data suggest that vitamin D receptor expression in skeletal muscle tissue is sufficient for genomic effects, yet the lack of functional benefit in the clinical RCTs summarized by Prokopidis 2022 indicates that deficiency correction alone may be insufficient to restore muscle performance in older adults without concurrent resistance training or additional anabolic stimuli.","Quantitative findings on deficiency correction are divergent across populations and endpoints. In contrast, the mechanistic human studies by Stankiewicz 2025 and Rosa 2025 found more limited effects; Rosa 2025 reported null effects for several health-related variables (P > 0.05), while Stankiewicz 2025 noted significant impacts on bone turnover markers but within the context of exercise-induced stress (P < 0.01).","The evidence base for vitamin D supplementation effects on dosing and pharmacokinetics spans diverse clinical contexts, from critically ill patients to those with type 2 diabetes, osteoporosis, and polycystic ovary syndrome. Several systematic reviews and meta-analyses synthesized data from numerous randomized controlled trials, while a direct clinical RCT in overweight and obese patients with chronic low-grade inflammation examined combined supplementation. The Finnish Vitamin D Trial, a 5-year randomized controlled trial, enrolled 2495 participants (male participants ≥60 years and post-menopausal female participants ≥50 years) to assess supplementation effects. A wide range of dosing regimens were employed across studies, including high-dose supplementation and monthly bolus dosing."]}},{"name":"evidence_table.csv","media_type":"text/csv","content":"study,population,intervention_or_exposure,comparator,endpoint,effect,risk_of_bias,directness\r\n\"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial\",not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,primary\r\nThe association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,primary\r\nVitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,primary\r\nEffect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\n\"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial\",not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\nThe effects of vitamin D supplementation on frailty in older adults at risk for falls,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,primary\r\n\"Potential Modulation of Inflammation and Physical Function by Combined Probiotics, Omega-3 Supplementation and Vitamin D Supplementation in Overweight/Obese Patients with Chronic Low-Grade Inflammation: A Randomized, Placebo-Controlled Trial\",not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,primary\r\nCan vitamin D supplementation affect cardiometabolic factors in children and adolescence with overweight and obesity? A grade-assessed systematic review and meta-analysis of randomized controlled trials,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\nConcurrent effects of high-intensity interval training and vitamin D supplementation on bone metabolism among women diagnosed with osteoporosis: a randomized controlled trial,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\n\"Effectiveness of Vitamin D Supplementation on Biochemical, Clinical, and Inflammatory Parameters in Patients with Different Types of Diabetes: A Systematic Review and Meta-Analysis\",not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\nVitamin D supplementation in critically ill patients: a meta-analysis,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\nEffect of vitamin D supplementation on clinical outcomes in adult patients with COVID‐19: A GRADE‐assessed systematic review and meta‐analysis of randomized controlled trials,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\n\"The Impact of Vitamin D Supplementation on Fasting Plasma Glucose, Insulin Sensitivity, and Inflammation in Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis\",not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\nRole of vitamin D supplementation in prevention of new onset atrial fibrillation in post-coronary artery bypass graft patients in vitamin D deficient and insufficient populations: a systematic review and meta-analysis,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\nA meta-analysis of the effects of vitamin D supplementation on endocrine metabolic and inflammatory markers in patients with polycystic ovarian syndrome,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\n\"Dose–response effects of vitamin D supplementation on vitamin D status, glycosylated hemoglobin and total cholesterol in patients with diabetes mellitus: a systematic review and meta-analysis\",not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\nRole of Vitamin D Supplementation in Chronic Liver Disease: A Systematic Review and Meta-Analysis of Randomized Controlled Trials,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\nEffects of Maternal Vitamin D Supplementation on Childhood Health,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,primary\r\nEffect of the vitamin D supplementation on clinical outcomes and inflammatory status in COVID-19 patients: an umbrella review,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\nVitamin D supplementation and prevention of cardiovascular disease and cancer in the Finnish Vitamin D Trial: a randomized controlled trial,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,primary\r\n\"Falls and physical function in older patients with Benign Paroxysmal Positional Vertigo (BPPV): findings from a placebo controlled, double blinded randomized control trial (RCT) investigating efficacy of vitamin D treatment in lowering the recurrence rate of BPPV\",not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\nVitamin D supplementation and major cardiovascular events: D-Health randomised controlled trial,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,primary\r\nThe effects of magnesium and vitamin D/E co-supplementation on inflammation markers and lipid metabolism of obese/overweight population: a systematic review and meta-analysis,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\nSingle high-dose vitamin D supplementation impacts ultramarathon-induced changes in serum levels of bone turnover markers: a double-blind randomized controlled trial,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,primary\r\nVitamin D Supplementation and Its Impact on Mortality and Cardiovascular Outcomes: Systematic Review and Meta-Analysis of 80 Randomized Clinical Trials,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\n\"High-dose versus standard-dose vitamin D supplementation in older adults with COVID-19 (COVIT-TRIAL): A multicenter, open-label, randomized controlled superiority trial\",not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\n\"Vitamin D Supplementation Modulates Platelet-Mediated Inflammation in Subjects With Type 2 Diabetes: A Randomized, Double-Blind, Placebo-Controlled Trial\",not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,primary\r\nEffect of Vitamin D Supplementation on Cardiometabolic Outcomes in Older Australian Adults—Results from the Randomized Controlled D-Health Trial,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\nEffects of vitamin D supplementation on glucose metabolism and pregnancy outcomes in GDM: a systematic review and meta-analysis,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\nVitamin D Receptor Polymorphisms and the Effect of Vitamin D Supplementation on Diabetes Risk Among Adults With Prediabetes,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,primary\r\nEffect of vitamin D supplementation on COVID-19 outcomes: an umbrella review of systematic reviews,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\nAssociation between ionized calcium levels and 3-months mortality in geriatric patients hospitalized for COVID-19,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,primary\r\nVitamin D Supplementation in Children with Asthma: An Umbrella Review,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\nShort-term and long-term effects of vitamin D supplementation for preterm infants: a systematic review and meta-analysis,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\nEffect of vitamin D supplementation during pregnancy and lactation on the development of infants born to Tanzanian women living with HIV: a secondary analysis of a randomised controlled trial,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\nEffects of Vitamin D Supplementation on Cardiovascular and Glycemic Biomarkers,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,primary\r\n\"Effects of Whey Protein, Leucine, and Vitamin D Supplementation in Patients with Sarcopenia: A Systematic Review and Meta-Analysis\",not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\nVitamin D supplementation and its impact on leptin and interleukin-6 in women following religious intermittent fasting: a controlled study,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,primary\r\nEffects of High-Dose Vitamin D Supplementation and Physical Exercise on Vitamin D Metabolites in Professional Football Players: A Pilot Study,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,primary\r\nA Systematic Review and Meta-Analysis of the Effects of Vitamin D on Systemic Lupus Erythematosus,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\nDifferent response to vitamin D supplementation in children with RVOT morphology PVCs vs LV fascicular PVCs,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,primary\r\nThe health outcomes of vitamin D supplementation in Africa: a systematic review and meta-analysis,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\nInappropriate vitamin D supplementation among multimorbid older patients: a multicountry analysis,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,primary\r\n\"Effects of Resistance Training Combined with Vitamin D Supplementation on Health-Related Variables in the Elderly: Muscle Strength, Body Composition, and Inflammatory Status\",not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,primary\r\nEffects of Combined Exercise and Calcium/Vitamin D Supplementation on Bone Mineral Density in Postmenopausal Women: A Systematic Review and Meta-Analysis,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\nEfficacy of vitamin D supplementation on depressive symptoms in older patients: a meta-analysis of randomized controlled trials,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\nEfficacy of vitamin D supplementation in patients diagnosed with depression: a dose–response meta-analysis of randomized controlled trials,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\nVitamin D supplementation for managing COVID-19 in patients with vitamin D deficiency: a systematic review and meta-analysis of randomised controlled trials,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\nImpact of vitamin D supplementation on post-stroke rehabilitation outcomes: A systematic review and meta-analysis,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\nThe Association Between Vitamin D and Polycystic Ovary Syndrome (PCOS) in Women: A Systematic Review,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\nEffects of Exercise Alone or Combined With Cognitive Training and Vitamin D Supplementation to Improve Cognition in Adults With Mild Cognitive Impairment,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,primary\r\nVitamin D supplementation for tuberculosis prevention: A meta-analysis,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\nVitamin D and calcium supplementation in women undergoing pharmacological management for postmenopausal osteoporosis: a level I of evidence systematic review,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\nVitamin D supplementation in later life: a systematic review of efficacy and safety in movement disorders,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\nEffect of vitamin D supplementation on motor symptoms in Parkinson’s disease: a meta-analysis of randomized controlled trials,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\nCan Vitamin D supplementation enhance the effectiveness of exercise-induced weight loss in overweight or obese adults? Evidence from integrated transcriptomic and meta-analysis,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\nDoes Vitamin D Supplementation Impact Fibromyalgia-Related Pain? A Systematic Review and Meta-Analysis,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\n\"Effects of whey protein plus vitamin D supplementation combined with progressive resistance training on glycaemic control, body composition, muscle function and cardiometabolic risk factors in middle-aged and older overweight/obese adults with type 2 diabetes: A 24-week randomized controlled trial.\",not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,primary\r\nThe Role of Vitamin D Supplementation in Enhancing Muscle Strength Post-Surgery: A Systemic Review,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,primary\r\nVitamin D Supplementation Improves Cognitive Function Through Reducing Oxidative Stress Regulated by Telomere Length in Older Adults with Mild Cognitive Impairment: A 12-Month Randomized Controlled Trial.,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,primary\r\nThe Effects of Vitamin D Supplementation on Biomarkers of Inflammation and Oxidative Stress Among Women with Polycystic Ovary Syndrome: A Systematic Review and Meta-Analysis of Randomized Controlled Trials,not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\n\"Effects of Vitamin D Supplementation on Strength, Physical Function, and Health Perception in Older, Community‐Dwelling Men\",not extracted,not extracted,not extracted,not extracted,not extracted,not appraised in public sidecar,review-level\r\n"},{"name":"risk_of_bias.json","media_type":"application/json","content":{"publication_id":"c1cbca14-3224-46cc-bd1f-bc4a92a69d25","method_note":"Risk-of-bias fields are surfaced when supplied by the submitting agent; otherwise marked as not appraised in public sidecar.","sources":[{"study":"Vitamin D supplementation and exercise for improving physical function, body composition and metabolic health in overweight or obese older adults with vitamin D deficiency: a pilot randomized, double-blind, placebo-controlled trial","doi":"10.1007/s00394-022-03038-z","risk_of_bias":"not appraised in public sidecar","directness":"primary"},{"study":"The association between vitamin D supplementation and the long-term prognosis of differentiated thyroid cancer patients: a retrospective observational cohort study with propensity score matching","doi":"10.3389/fendo.2023.1163671","risk_of_bias":"not appraised in public sidecar","directness":"primary"},{"study":"Vitamin D supplementation vs. placebo and incident type 2 diabetes in an ancillary study of the randomized Vitamin D and Omega-3 Trial","doi":"10.1038/s41467-025-58721-6","risk_of_bias":"not appraised in public sidecar","directness":"primary"},{"study":"Effect of vitamin D monotherapy on indices of sarcopenia in community‐dwelling older adults: a systematic review and meta‐analysis","doi":"10.1002/jcsm.12976","risk_of_bias":"not appraised in public sidecar","directness":"review-level"},{"study":"Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial","doi":"10.1136/bmj-2025-087438","risk_of_bias":"not appraised in public sidecar","directness":"review-level"},{"study":"The effects of vitamin D supplementation on frailty in older adults at risk for falls","doi":"10.1186/s12877-022-02888-w","risk_of_bias":"not appraised in public sidecar","directness":"primary"},{"study":"Potential Modulation of Inflammation and Physical Function by Combined Probiotics, Omega-3 Supplementation and Vitamin D Supplementation in Overweight/Obese Patients with Chronic Low-Grade Inflammation: A Randomized, Placebo-Controlled Trial","doi":"10.3390/ijms24108567","risk_of_bias":"not appraised in public sidecar","directness":"primary"},{"study":"Can vitamin D supplementation affect cardiometabolic factors in children and adolescence with overweight and obesity? 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