Cut Down on Common Colds with Vitamin C

Supplementing with vitamin C may decrease the frequency of the common cold, but does not appear to affect the duration or severity of the infection, reports the European Journal of Clinical Nutrition (2005;doi:10.1038/sj.ejcn.1602261).

The common cold is a kind of upper respiratory tract infection that may be caused by a number of different viruses. While most colds tend to pass in about a week, the coughing, runny nose, fever, body aches, and sore throat may linger longer, sometimes giving way to other infections such as bronchitis or sinusitis. Most colds are spread by direct contact with an object that an infected person has handled, or by being in close proximity to the sneezes and coughs of a person with a cold.

Vitamin C is necessary for proper immune function. It also aids in wound healing and acts as an antioxidant, protecting against heart disease and other conditions related to damaging free radicals. Rich food sources of vitamin C include broccoli, red peppers, strawberries, and citrus fruits.

Several studies have shown that vitamin C supplementation decreases the duration and severity of the common cold, but most trials have failed to show that it actually reduces infection frequency. These negative studies, however, were relatively short (ranging from two to nine months) and were probably not long enough to detect a true effect of vitamin C over a variety of conditions.

To further evaluate the relationship between vitamin C intake and the frequency, severity, and duration of the common cold, 244 people, aged 40 to 69 years, completed a five-year study. The participants received either 50 mg (low-dose) or 500 mg (high-dose) of vitamin C each day. Common cold episodes were documented at clinic visits, which took place every three months. The participants answered questions regarding colds, including the presence and intensity of runny or stuffy nose, sore throat, fever, headache, muscle pain, as well as the number of days spent in bed, number of days of missed work, and the duration of each cold episode.

Supplementing with 500 mg of vitamin C per day significantly reduced the frequency of the common cold. People in the high-dose vitamin C group were about 70% less likely to catch one or more colds per year than were members of the low-dose group. There were no significant differences between the groups with respect to the severity of symptoms or the duration of the cold episodes. These results should be interpreted with caution, however, as the number of participants who developed colds was small and, therefore, the results were difficult to analyze statistically. In addition, most of the studies that showed a reduction in the duration of colds used larger vitamin C doses, such as 1,500 to 4,000 mg per day.

This study demonstrates that vitamin C, when taken at a moderate daily dose for several years, reduces the frequency of the common cold. Although no changes were detected with respect to the duration and severity of the episodes, numerous other studies have shown that somewhat large doses of vitamin C do, in fact, shorten the duration and lessen the symptoms of the common cold. As vitamin C taken within the range studied above is affordable and does not cause any dangerous side effects, people fighting colds may still be advised to try vitamin C.

Kimberly Beauchamp, ND, earned her bachelor’s degree from the University of Rhode Island and her Doctorate of Naturopathic Medicine from Bastyr University in Kenmore, WA. She cofounded South County Naturopaths in Wakefield, RI. Dr. Beauchamp practices as a birth doula and lectures on topics including whole-foods nutrition, detoxification, and women’s health.

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