Vitamin D supplementation to prevent acute respiratory infections: systematic review and meta-analysis of stratified aggregate data
Abstract
Background: A 2021 meta-analysis of 37 randomised controlled trials (RCTs) of vitamin D supplementation for prevention of acute respiratory infections (ARI) revealed a statistically significant protective effect of the intervention (odds ratio [OR] 0.92, 95% confidence interval [CI] 0.86 to 0.99). Since then, 6 eligible RCTs have completed, including one large trial (n=15,804). Methods: Updated systematic review and meta-analysis of data from RCTs of vitamin D for ARI prevention using a random effects model. Sub-group analyses were done to determine whether effects of vitamin D on risk of ARI varied according to baseline 25-hydroxyvitamin D (25[OH]D) concentration, dosing regimen or age. We searched MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, Web of Science and the ClinicalTrials.gov were searched between May 2020 (previous search) and April 2024. No language restrictions were imposed. Double-blind RCTs supplementing vitamin D for any duration, with placebo or low-dose vitamin D control, were eligible if approved by Research Ethics Committee and if ARI incidence was collected prospectively and pre-specified as an efficacy outcome. Aggregate data, stratified by baseline 25(OH)D concentration and age, were obtained from study authors. The study was registered with PROSPERO (no. CRD42024527191). Findings: We identified 6 new RCTs (19,337 participants). Data were obtained for 16,086 (83.2%) participants in 3 new RCTs and combined with data from 48,488…
How strong is the evidence?
Evidence Hub reads this as a meta-analysis, done in people. Its evidence level is 1 of 5 (Highest · pooled evidence). Pooled evidence from several studies sits at the top of the evidence pyramid. Reported size: 48,488 participants or records.
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