Vitamin D Will Not Prevent Colds in Healthy Adults

Vitamin D supplementation had no effect on the frequency or severity of upper respiratory tract infections (URTIs) in healthy adults, researchers found, despite previous suggestion of the vitamin’s benefits to the immune system. 

To test the effects of vitamin D supplementation on the development of URTIs, researchers from the University of Otago in New Zealand followed 322 healthy adults between February of 2010 and November of 2011 in a randomized, double-blind, placebo-controlled trial. 

Participants randomized to vitamin D supplementation received an initial dose of 200,000 IU, 200,000 IU after 1 month, and 100,000 IU monthly for the 16 remaining months of the trial. 

Researchers evaluated the number of URTIs developed, duration and severity of URTIs, and the number of days participants missed work due to URTIs in their analysis. 

Statistically, no significant difference was found, with vitamin D participants developing 593 URTIs versus 611 in the placebo group. 

“[This trial] is the first study to convincingly show that vitamin D does not prevent colds in healthy adults,” researchers concluded. “However, it is important to note that very few people in our study had extremely low levels of vitamin D at the beginning.

“Further research is required to clarify whether there is benefit from supplementation in other populations and with other dosing regimens.’’

-Michael Potts