Vitamin C for the Common Cold: How Effective is it?

For the average, healthy person, vitamin C is unlikely to prevent the common cold. However, it may be beneficial in individuals who engage in extreme physical exercise or are exposed to cold temperatures, a new review reports.

Vitamin C (ascorbic acid) is a water-soluble vitamin that is necessary in the body to form collagen in bones, cartilage, muscle and blood vessels. It also aids in the absorption of iron. Dietary sources of vitamin C include fruits and vegetables, particularly citrus fruits such as oranges.

Researchers reviewed the results of 30 published studies involving 11,350 people who took at least 200 milligrams of vitamin C every day. The results were published in the latest edition of the The Cochrane Library.

Based on the collective data from these studies, routine consumption of vitamin C did not reduce the risk of the common cold in the general population. Although there was a slight reduction in the severity and duration of common cold symptoms in patients who took vitamin C regularly when compared to placebo, the results were not considered significant.

However, vitamin C may help prevents colds in a subgroup of individuals. In six trials that involved a total of 642 marathon runners, skiers and soldiers on sub-arctic exercises, vitamin C supplements reduced the incidence of the common cold by nearly 50 percent.

The review authors concluded that the failure of vitamin C supplementation to reduce the incidence of colds in the normal population indicates that routine preventative treatment is not rationally justified for community use. However, evidence suggests that it could be justified in people exposed to brief periods of severe physical exercise or cold environments.

Many other uses for vitamin C have been proposed, but few have been conclusively demonstrated as being beneficial in scientific studies. In particular, research in asthma, cancer and diabetes remain inconclusive, and no benefits have been found in the prevention of cataracts or heart disease.

Integrative therapies with strong or good scientific evidence in the prevention and/or treatment of the common cold include andrographis paniculata Nees, Kan Jang, borage seed oil and sage. For more information about vitamin C,