Does Vitamin C Cure the Common Cold?
December 20, 2007—At the first sign of a cold, many people reach for the vitamin C in hopes of warding off the illness or easing symptoms. A new study looking at the effects of vitamin C on the development, duration, and severity of a cold, suggests that while vitamin C may not reduce the incidence of colds in a general population, taking vitamin C may, in fact, reduce the duration of a cold and help prevent a cold in certain people.
Does vitamin C shorten a cold?
If you take it before the cold starts. The authors of the study reviewed 30 research trials that included 11,350 people who took 200 mg or more of vitamin C daily at various stages of a cold. Results of the review showed that taking vitamin C before a cold starts may reduce the duration by 8% for adults and 13.6% for children.
Does it reduce risk?
Only at “extremes.” The review also found that vitamin C taken before a cold starts does not reduce the incidence of colds in a general adult population but may reduce the incidence in people exposed to extreme physical or cold (temperature) stress. For example, a group of athletes and soldiers on sub-Arctic exercises who took daily vitamin C reduced cold risk by 50%.
Does it make a cold less severe?
Not if you’re already sick. According to the reviewed trials, vitamin C’s effects on cold severity were inconsistent. A slight benefit was attributed to vitamin C in reducing days absent from school or work, but according to the review no significant effect has been seen in trials to date on the duration or severity of colds when vitamin C is started after symptoms begin.
What do the experts say?
Critics of the current review suggest that 1 to 3 grams of vitamin C is too small an amount and that research is needed on the effects of higher doses. Dr. Harri Hemila, lead author of the study, and his colleague state that, “studies on the therapeutic use of high doses of 4 grams and 8 grams on the day of the onset of respiratory symptoms are tantalizing and deserve further assessment.” Dr. Harri Hemila and his colleague state that “there seems no justification for routine megadose vitamin C supplementation in the normal population.” They add that taking vitamin C preventatively “may be justified in those exposed to severe physical exercise or cold stress or both.”
They also point out that to date none of the trials that looked at using vitamin C after a cold begins have examined the effect of vitamin C on children, even though trials that used vitamin C preventatively have found a substantially greater beneficial effect on duration in children, and they recommend further research in this area.
What’s the bottom line?
While vitamin C has been shown to affect disease resistance in numerous animal studies, we still do not have the full answer on how much vitamin C might help people ward off disease. And since the review looked at 30 studies that used different amounts for different lengths of time, the optimal amount for combating the cold remains to be discovered. For now, a person suffering from cold symptoms should eat a balanced diet that provides a wide variety of vitamins and minerals needed for health, and talk to a doctor about an appropriate amount of supplemental vitamin C to help shorten the duration.
Alan R. Gaby, MD, Healthnotes chief science officer, has concluded from his review of the vitamin C research, that adults who take 500 to 1,000 mg of vitamin per day preventively, and increase to 1,500 to 4,000 mg per day at the first sign of a cold, can reduce the duration and severity of colds by approximately 30%.
(Cochrane Database of Systematic Reviews 2007:3; article number CD000980. doi:10.1002/14651858.cd000980.pub3.)
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Jane Hart, MD, board-certified in internal medicine, serves in a variety of professional roles including consultant, journalist, and educator. Dr. Hart, a Clinical Instructor at Case Medical School in Cleveland, Ohio, writes extensively about health and wellness and a variety of other topics for nationally recognized organizations, Web sites, and print publications. Sought out for her expertise in the areas of integrative and preventive medicine, she is frequently quoted by national and local media. Dr. Hart is a professional lecturer for healthcare professionals, consumers, and youth and is a regular corporate speaker.
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