A randomized, placebo-controlled trial of vitamin D supplements did not demonstrate that they can ward off the respiratory tract infections so common at this time of year. The 759 adult volunteers were divided into four groups that received either 1,000 IU vitamin D3, 1,200 mg calcium, both or placebo. The study lasted four years, with no difference in the amount of time sick among any of the groups. The researchers concluded that vitamin D did not help prevent or shorten upper respiratory infections.
[Clinical Infectious Diseases, online Sept. 6, 2013]
Despite this disappointment with vitamin D, there are some natural approaches that can be helpful against seasonal respiratory tract infections. You can learn more in our Guide to Colds, Coughs and the Flu.
