Vitamin D seems to be the wonder supplement these days, with research touting its benefits in fighting everything from osteoporosis to heart disease. Now, a new study finds it may help you fight the flu. Researchers at Yale University School of Medicine and Greenwich Hospital followed nearly 200 healthy adults over the fall and winter of 2009-2010. They wanted to see if declining amounts of vitamin D, typically seen in cooler seasons, might be a factor in the increased number of respiratory viral infections during that time. Participants had blood samples taken monthly, but were not told their vitamin D levels were being measured. They were also asked to report any evidence of respiratory tract infection or flu, including nasal congestion, sore throat, cought, fever, chills and fatigue. Those who reported illness were seen the same day at the study site by a board-certified Infectious Diseases investigator with follow-up every 1-3 days by phone. Researchers recorded the length of illness and any medications that were administered.
The results: 18 participants maintained vitamin D levels (38ng/ml or higher) over the course of the study and 16.6% (3) of them developed viral infections. The remaining 180 experienced declining vitamin D amounts and 45% (81) of them developed viral infections, but those in this group with higher vitamin D levels were ill for fewer days.
Researchers say the data suggests taking vitamin D supplements to achieve a blood level 38 ng/ml or higher could provide a big health benefit by reducing the flu and other respiratory infections.
How much vitamin D is currently recommended for adults?
The study is published in the journal PloS ONE.