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Vitamin D May Help Prevent Colds and Flu

People with the lowest levels of vitamin D in their blood are the most likely to catch colds, showed an analysis of the Third National Health and Nutrition Examination survey (February 2009).

The researchers, A. Ginde, J. Mansbach and C. Camargo Jr. studied data from 19,000 U.S adults and found that those with less than 10 nanograms of vitamin D per milliliter of blood, considered low, were associated with a nearly 40 percent increased risk of respiratory infection (common “colds”) than those with vitamin D levels of 30 ng or higher. The findings were consistent across all races, ages and during all seasons. Furthermore, the researchers noted that the association between low levels of vitamin D and colds/influenza were stronger in study volunteers with asthma and chronic obstructive pulmonary disease (COPD).

In an interventional study ”Epidemic influenza and vitamin D” (September 2006), the researchers Cannell et al. showed that the seasonality of influenza is tied to vitamin D and that vitamin D reduced the incidence of viral respiratory infections in children. The seasonality hypothesis is however related to sun-derived vitamin D. So in regards to daily oral dosage required to prevent seasonal respiratory infections remain to be seen, but the researchers are suggesting that a doses of 1000-2000 IU/ per day for several days may be useful in the treatment of those viral respiratory infections that peak in wintertime.

References: Cannell J.J., Vieth R., Umhau J.C., Holick M.F, Grant W.B., Madronich S., Garland C.F. and Giovannucci E. (September, 2006), Epidemic Influenza and vitamin D, In: Epidemiologic Infections.

Ginde A.A., Mansbach J.M., Camargo Jr. C.A,(February 2009), Association Between Serum 25-Hydroxivitamin D Level and Upper Respiratory Tract Infection in the Third National Health and Nutrition Examination Survey, In: Archives Internal Medicine.