2017/02/15 by Adrian R. Martineau, David A. Jolliffe, Richard Hooper +22 · 1 voice
Medicine · Nursing · #Vitamin D Research Studies #Chronic Obstructive Pulmonary Disease (COPD) Research #Vitamin C and Antioxidants Research
paper · pdf · doi:10.1136/bmj.i6583
openalex publication_date 2017/02/15 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/30
<b>Objectives</b> To assess the overall effect of vitamin D supplementation on risk of acute respiratory tract infection, and to identify factors modifying this effect. <b>Design</b> Systematic review and meta-analysis of individual participant data (IPD) from randomised controlled trials. <b>Data sources</b> Medline, Embase, the Cochrane Central Register of Controlled Trials, Web of Science, ClinicalTrials.gov, and the International Standard Randomised Controlled Trials Number registry from inception to December 2015. <b>Eligibility criteria for study selection</b> Randomised, double blind, placebo controlled trials of supplementation with vitamin D<sub>3</sub> or vitamin D<sub>2</sub> of any duration were eligible for inclusion if they had been approved by a research ethics committee and if data on incidence of acute respiratory tract infection were collected prospectively and prespecified as an efficacy outcome. <b>Results</b> 25 eligible randomised controlled trials (total 11 321 participants, aged 0 to 95 years) were identified. IPD were obtained for 10 933 (96.6%) participants. Vitamin D supplementation reduced the risk of acute respiratory tract infection among all participants (adjusted odds ratio 0.88, 95% confidence interval 0.81 to 0.96; P for heterogeneity <0.001). In subgroup analysis, protective effects were seen in those receiving daily or weekly vitamin D without additional bolus doses (adjusted odds ratio 0.81, 0.72 to 0.91) but not in those receiving one or more bolus doses (adjusted odds ratio 0.97, 0.86 to 1.10; P for interaction=0.05). Among those receiving daily or weekly vitamin D, protective effects were stronger in those with baseline 25-hydroxyvitamin D levels <25 nmol/L (adjusted odds ratio 0.30, 0.17 to 0.53) than in those with baseline 25-hydroxyvitamin D levels ≥25 nmol/L (adjusted odds ratio 0.75, 0.60 to 0.95; P for interaction=0.006). Vitamin D did not influence the proportion of participants experiencing at least one serious adverse event (adjusted odds ratio 0.98, 0.80 to 1.20, P=0.83). The body of evidence contributing to these analyses was assessed as being of high quality. <b>Conclusions</b> Vitamin D supplementation was safe and it protected against acute respiratory tract infection overall. Patients who were very vitamin D deficient and those not receiving bolus doses experienced the most benefit. <b>Systematic review registration</b> PROSPERO CRD42014013953.