10, 2010, doi: 10.3945/ajcn.2009.29094 Am J Clin Nutr May 2010 vol. 91 no. 5 1255-1260
? 2010 American Society for Nutrition
Randomized trial of vitamin D supplementation to prevent seasonal influenza A in schoolchildren
Mitsuyoshi Urashima,
Takaaki Segawa,
Minoru Okazaki,
Mana Kurihara,
Yasuyuki Wada, and
Hiroyuki Ida
Abstract
Background: To our knowledge, no rigorously designed clinical trials have evaluated the relation between vitamin D and physician-diagnosed seasonal influenza.
Objective: We investigated the effect of vitamin D supplements on the incidence of seasonal influenza A in schoolchildren.
Design: From December 2008 through March 2009, we conducted a randomized, double-blind, placebo-controlled trial comparing vitamin D3 supplements (1200 IU/d) with placebo in schoolchildren. The primary outcome was the incidence of influenza A, diagnosed with influenza antigen testing with a nasopharyngeal swab specimen.
Results: Influenza A occurred in 18 of 167 (10.8%) children in the vitamin D3 group compared with 31 of 167 (18.6%) children in the placebo group [relative risk (RR), 0.58; 95% CI: 0.34, 0.99; P = 0.04]. The reduction in influenza A was more prominent in children who had not been taking other vitamin D supplements (RR: 0.36; 95% CI: 0.17, 0.79; P = 0.006) and who started nursery school after age 3 y (RR: 0.36; 95% CI: 0.17, 0.78; P = 0.005). In children with a previous diagnosis of asthma, asthma attacks as a secondary outcome occurred in 2 children receiving vitamin D3 compared with 12 children receiving placebo (RR: 0.17; 95% CI: 0.04, 0.73; P = 0.006).
Conclusion: This study suggests that vitamin D3 supplementation during the winter may reduce the incidence of influenza A, especially in specific subgroups of schoolchildren. This trial was registered at
https://center.umin.ac.jp as UMIN000001373.
Received December 17, 2009.
Accepted February 11, 2010.
