Does Vitamin C Prevent Colds?

Dr. Sharon Orrange
Dr. Orrange is an Associate Professor of Clinical Medicine in the Division of Geriatric, Hospitalist and General Internal Medicine at the Keck School of Medicine of USC.
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Yes, we are still investigating this question. Cold and flu season is coming and vitamin C is often touted as a natural remedy for the common cold. Patients ask me about it every week. A 2013 look at several studies, a meta-analysis, of over 11,000 people did conclude that regular vitamin C supplementation (at least 200 mg per day) slightly reduced the duration of cold symptoms. The problem was that this was only an 8 percent reduction in the duration of cold symptoms and most people didn’t notice that difference.

What about taking high doses once I start getting sick? This question has been asked and answered in several studies and you may not like the answer. High doses of vitamin C started after symptom onset have not been shown to reduce symptom duration or severity. In addition, there is no consistent benefit of vitamin C on prevention of the common cold in the general population

But wait, some folks did benefit. An interesting finding what that there was a 50 percent decrease in the incidence of colds in a subset of patients exposed to vigorous activity, especially in extreme conditions (marathon runners and skiers). The reasons for the benefit in this group of patients are uncertain.

Dr O.

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