Although vitamin D use has long been known to provide potential benefits to bone health, it’s effects on immune health have been less established. But a new meta-analysis published in the British Medical Journal1 provides new evidence that vitamin D supplementation may help reduce the risk of acute respiratory tract infections.
The study included 25 randomized, double-blind, placebo-controlled trials assessing supplementation of vitamin D2 or vitamin D3 of any duration, all of which assessed incidence of acute respiratory tract infections. A total of 10,933 participants aged 0 to 95 years were included in the analysis.
Researchers found that vitamin D supplementation reduced the risk of acute respiratory tract infection among all participants, with the results suggesting that for every 33 people taking vitamin D supplements, one person would avoid infection. The vaccine designed to protect against influenza, by comparison, has a rate of protection of roughly one person for every 40 people who have received the vaccine, according to a 2014 study.2
The study also found that the protective effects of vitamin D supplementation were greater in subjects receiving daily or weekly doses without additional bolus doses. Protective effects were also especially strong in participants with vitamin D deficiencies at baseline, defined as 25-hydroxyvitamin levels less than 25 nmol/L. Vitamin D supplementation was not found to influence the proportion of participants experiencing one or more serious adverse events.
“Our study reports a major new indication for vitamin D supplementation—the prevention of acute respiratory tract infection,” researchers concluded. “Our results add to the body of evidence supporting the introduction of public health measures such as food fortification to improve vitamin D status, particularly in settings where profound vitamin D deficiency is common.”
Nutritional Outlook Magazine
1. Martineau AR et al., “Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data,” British Journal of Nutrition. Published online February 15, 2017.
2. Demicheli V et al., “Vaccines for preventing influenza in healthy adults,” Cochrane Database of Systematic Reviews. Published online March 13, 2014.