Date published: May 1, 2010
Vitamin D may ward off some types of flu, at least in children.
Researchers in Japan randomly assigned 334 schoolchildren aged 6 to 15 to take either vitamin D (1,200 IU a day) or a placebo starting in December 2008. By March 2009, 11 percent of the children taking vitamin D and 19 percent of the children taking the placebo were diagnosed with influenza A, which includes Hl NI. Vitamin D had no effect on influenza B, which is less common than influenza A.
Among children who had been diagnosed with asthma, only two attacks occurred in vitamin D takers, while 12 attacks occurred in placebo takers.
What to do: More studies are needed to know if vitamin D can prevent the flu in children or adults. However, it's worth taking 700 to 1,000 IU a day to make sure you get enough.
Am. J. Clin. Nutr. doi: 10.3945/ajcn.2009.29094.