Vitamin D Supplementation and Cognition in Adults: A Systematic Review of Randomized Controlled Trials.
Study Goal
The researchers aimed to synthesize evidence on whether vitamin D supplementation improves cognitive performance or slows neurocognitive disorders in adults.
Results Summary
The systematic review found mixed results, with no clear evidence supporting cognitive benefits from vitamin D supplementation. Half of the RCTs reported mixed outcomes, while the rest were split between negative and positive effects.
Population
Adults aged 18 and older, including cognitively healthy individuals and those with minor or major neurocognitive disorders.
Effective Dosage
Not specified
Duration
Not specified
Interactions
None mentioned
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
vitamin D supplementation | no change | cognition | adults | - | failed to find evidence supporting cognitive benefits | #1 |
vitamin D supplementation | no change | cognitive function | adults | - | failed to find evidence suggesting a causal association | #2 |
vitamin D supplementation | no change | cognitive performance | - | - | mixed results | #3 |
vitamin D supplementation | no change | cognitive performance | - | - | negative results | #4 |
vitamin D supplementation | increase | cognitive performance | - | - | positive effects | #5 |
vitamin D supplementation | no change | cognition | adults | - | does not support a role in enhancing cognition | #6 |
BACKGROUND: The role of vitamin D supplementation in improving cognition and slowing the incidence of minor and major neurocognitive disorders is a matter of debate. To our knowledge, no systematic review of randomized controlled trials (RCTs) has examined this question in adults. OBJECTIVES: The purpose of this systematic review is to synthesize the evidence regarding the effects of vitamin D supplementation on cognitive performance and neurocognitive disorders in adults. METHODS: A systematic search of scientific articles in English or French was conducted. The MEDLINE (PubMed), EMBASE (Ovid, EMBASE), PsychINFO, and Cochrane Central databases were searched for records without any limit on publication date in May 2021. Inclusion criteria were (1) human participants, (2) RCT, (3) participant age ≥ 18, (4) vitamin D supplementation as the intervention, and (5) cognition (i.e., cognitive performance or cognitive status such as cognitively healthy or minor and major neurocognitive disorder) as the primary outcome. Two independent reviewers both assessed all eligible studies' full texts and the risk of bias arising from methodological issues using a standardized procedure. RESULTS: Of the 2137 abstracts identified, 61 (2.9%) met screening inclusion criteria. After full text examination, 41 records (67.2%) were excluded. As a result, 20 RCTs (32.8%) were included in the systematic review. The review yielded mixed findings and, thus, failed to find evidence supporting cognitive benefits from vitamin D supplementation or suggesting a causal association between vitamin D and cognitive function. Half of the RCTs reported mixed results, one quarter negative results, and the last quarter positive effects for vitamin D supplementation on cognitive performance. The variability in serum 25-dihydroxyvitamin D concentration thresholds, the cognitive tests employed, the supplementation doses, and the samples' characteristics (i.e., ethnicity or number of participants) may explain these mixed findings. CONCLUSION: This systematic review of RCTs does not support a role for vitamin D supplementation in enhancing cognition in adults.