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New evidence: vitamin D prevents flu

A new study published in the peer-reviewed open access journal PloS ONE has confirmed that maintaining high levels of serum vitamin D prevents flu and other respiratory tract infections.

The study showed that men and women who had high levels of vitamin D in their blood were much less likely to acquire respiratory tract infections.

For the current double-blinded study, James R. Sabetta, M.D. at Greenwich Hospital and Yale University School of Medicine and colleagues followed 198 healthy adults during the fall and winter 2009 and 2010 for viral respiratory tract infections and their serum vitamin D levels.

The researchers tested blood samples drawn monthly from the participants to measure 25-hydroxyvitamin D and the participants were asked to promptly report any symptom of an acute respiratory tract infection including nasal congestion, sore throat, or cough with or without fever, chills, fatigue and general malaise.

Only 16.6 percent of those who maintained vitamin D levels of 38 ng of ml or higher got viral infections during the study period while 45 percent of those who had lower levels of serum vitamin D developed viral infections including flu.

The results of the study suggest that taking vitamin D supplements in the fall and winter can help prevent flu and other types of respiratory tract infections.  

Flu rarely occurs in the summer when people are often exposed to the sun and they likely maintain a high level of vitamin D.

Previous epidemiological and laboratory studies that vitamin D helps prevent flu, probably other types of infections as well.  

This vitamin is involved in the production of naturally occurring antibacterial peptides in the body which help kill viruses and microbes, according to Dr. JOhn Cannell, a vitamin D expert and founder of Vitamin D Council.

Dr. Cannell reported last year in his newsletter that two physicians, one in Wisconsin and the other in George observed that people who maintained high levels of vitamin D by taking vitamin D supplements were much less likely to have H1N1 flu and other flu-like infections.

Jimmy Downs