Vitamin D fights many health problems – an umbrella review of 508 studies – July 2022

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Vitamin D and Multiple Health Outcomes: An Umbrella Review of Observational Studies, Randomized Controlled Trials, and Mendelian Randomization Studies

Advances in Nutrition, Vol 13, #4, July 2022, Pages 1044–1062, https://doi.org/10.1093/advances/nmab142
Di Liu, Xiaoni Meng, Qiuyue Tian, Weijie Cao, Xin Fan, Lijuan Wu, Manshu Song, Qun Meng, Wei Wang, Youxin Wang
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Consistency between Meta-analyses of observed and MR

Meta-analyses of Observed and RCT

Details of Meta-analyses of Observed and RCT

Observational studies, randomized controlled trials (RCTs), and Mendelian randomization (MR) studies have yielded inconsistent results on the associations of vitamin D concentrations with multiple health outcomes. In the present umbrella review we aimed to evaluate the effects of low vitamin D concentrations and vitamin D supplementation on multiple health outcomes. We summarized current evidence obtained from meta-analyses of observational studies that examined associations between vitamin D concentrations and multiple health outcomes, meta-analyses of RCTs that investigated the effect of vitamin D supplementation on multiple health outcomes, and MR studies that explored the causal associations of vitamin D concentrations with various diseases (international prospective register of systematic reviews PROSPERO registration number CRD42018091434).
A total of

• 296 meta-analyses of observational studies
  • comprising 111 unique outcomes,
• 139 meta-analyses of RCTs
  • comprising 46 unique outcomes, and
• 73 MR studies
  • comprising 43 unique outcomes

were included in the present umbrella review.
Twenty-eight disease outcomes were identified by both meta-analyses of observational studies and MR studies.
Seventeen of these reported disease outcomes had consistent results, demonstrating that lower concentrations of vitamin D were associated with a higher risk for all-cause mortality,

• Alzheimer's disease,
• hypertension,
• schizophrenia, and
• type 2 diabetes.

The combinations of consistent evidence obtained by meta-analyses of observational studies and MR studies together with meta-analyses of RCTs showed that vitamin D supplementation was associated with a decreased risk for all-cause mortality but not associated with the risk for Alzheimer's disease, hypertension, schizophrenia, or type 2 diabetes.
The results indicated that vitamin D supplementation is a promising strategy with long-term preventive effects on multiple chronic diseases and thus has the potential to decrease all-cause mortality. However, the current vitamin D supplementation strategy might not be an efficient intervention approach for these diseases, suggesting that new strategies are highly needed to improve the intervention outcomes.

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667 Meta-analyses in VitaminDWiki (most are for Vitamin D trials)

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VitaminDWiki - Proof that Vitamin D Works