How effective is vitamin D for preventing colds and flu?

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Dr. Mehmet Oz, MD
Cardiology (Cardiovascular Disease)
Vitamin D is a vital vitamin/hormone that can come from sunlight, diet, and some supplements. It bestows many health benefits, including an improved ability to prevent some types of cancer. However, a recent study in the Journal of the American Medical Association questions vitamin D’s ability to prevent colds, the flu, and other similar upper respiratory tract infections (URTIs), which include symptoms like runny nose, cough, sore throat, or nasal stuffiness.

Researchers followed 294 New Zealanders for 18 months. One-half of the participants received oral vitamin D3 supplements at specialized monthly dosages. The control group received a similar-looking placebo pill. All participants had normal vitamin D levels at the start of the study.

At the end of the observation period, the researchers noted a similar number of URTIs in both groups and concluded that monthly administration of vitamin D3 “did not reduce the incidence or severity of URTIs in healthy, predominantly European adults with near-normal vitamin D levels.”

Despite the results of this recent study, don’t throw away your vitamin D supplements just yet. This study is one of several that has shown conflicting evidence of vitamin D’s cold-fighting effects. Another study on Mongolian schoolchildren in winter found that taking vitamin D supplements led to a 50% reduction in acute respiratory infections. It’s quite possible that the URTI-fighting effects of vitamin D supplements can vary between different populations or at different geographic locations, where sunlight exposure varies.

Furthermore, keep in mind that past epidemiological studies have shown an association between low vitamin D levels and various respiratory illnesses, including an increased risk of getting tuberculosis. Other researchers have touted vitamin D’s bug-fighting properties. It has been shown to reduce the body’s risk of infection by altering its “modulation of anti-microbial peptides (AMP)” and by “enhancing [the] clearance of invading organisms” in the respiratory tract, preventing infections.

This content originally appeared on doctoroz.com

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.