Vitamin D2 & D3: Did 2017 meta-analysis show persons taking 800 IUs of vitamin D or more had a lower risk of influenza and other respiratory viruses than those who did not? Yes, it did!

by Paul Alexander

Vitamin D protected against acute respiratory tract infection; independent associations between low serum concentrations of 25-hydroxyvitamin D susceptibility to acute respiratory tract infections



A Systematic review and meta-analysis of individual participant data (IPD) from randomised controlled trials.

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.’


Relevant associated research:


Cannell JJ, Vieth R, Umhau JC, et al. Epidemic influenza and vitamin D. Epidemiol Infect2006;356:1129-40. doi:10.1017/S0950268806007175 pmid:16959053.


Jolliffe DA, Griffiths CJ, Martineau AR. Vitamin D in the prevention of acute respiratory infection: systematic review of clinical studies. J Steroid Biochem Mol Biol2013;356:321-9. doi:10.1016/j.jsbmb.2012.11.017 pmid:23220552.


Bergman P, Lindh AU, Björkhem-Bergman L, Lindh JD. Vitamin D and Respiratory Tract Infections: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. PLoS One2013;356:e65835. doi:10.1371/journal.pone.0065835 pmid:23840373.


Charan J, Goyal JP, Saxena D, Yadav P. Vitamin D for prevention of respiratory tract infections: A systematic review and meta-analysis. J Pharmacol Pharmacother2012;356:300-3. doi:10.4103/0976-500X.103685 pmid:23326099.