Vitamin Studied For Immune-Supporting Ability

A recently published clinical trial examined the effect of supplementation with a particular vitamin on the incidence of influenza A infection in school children. According to the Centers for Disease Control and Prevention (CDC), 5 to 20 percent of Americans develop the flu during each flu season, and children are 2-3 times more likely than adults to become ill from the flu. Additionally, the CDC estimates that 200,000 individuals are hospitalized and about 36,000 Americans die from the flu and its complications every year.

In this new randomized, double-blind, placebo-controlled trial, 167 school children were supplemented with either 1,200 IU vitamin D3 per day or a placebo from December 2008 through March 2009. The children were followed to evaluate the incidence of Influenza A infections, which were confirmed with nasopharyngeal swabs, which were tested for the presence of the influenza-antigen.

The results showed that influenza occurred in 10.8 percent of the children in the group receiving vitamin D3 and in 18.6 percent of children in the placebo group. This equates to a 42 percent decrease in the relative risk of developing influenza A infection with vitamin D3 supplementation. Furthermore, in children that had not previously taken a vitamin D supplement or children who had started nursery school after age 3, there was a 64 percent decrease in the risk of developing influenza A infection with vitamin D3 supplementation compared to the placebo group. The study also showed that in subjects with asthma, there was a reduction in the risk of asthma attacks by 83 percent in the children receiving vitamin D3 compared to the children with asthma in the placebo group.

The researchers concluded, “This study suggests that vitamin D3 supplementation during the winter may reduce the incidence of influenza A, especially in specific subgroups of schoolchildren.”

Reference:

Urashima M, Segawa T, Okazaki M, Kurihara M, Wada Y, Ida H. Randomized trial of vitamin D supplementation to prevent seasonal influenza A in schoolchildren. Am J Clin Nutr. 2010 Mar 10. Published Online ahead of Print.