Harvard Men's Health Watch

Ask the doctor: Vitamin C for health?

Q. Whatever happened to the idea that taking vitamin C could boost your immune system and prevent colds? Is there still a possibility it could work?

A. Vitamin C, also known as ascorbic acid, was promoted as a health supplement for decades, achieving its greatest renown in the 1970s through the writings of scientist Linus Pauling. Despite the excitement about its natural antioxidant function, vitamin C does not appear to prevent colds, and its ability to shorten the duration of colds is minimal. A recent summary of 29 studies involving more than 10,000 people confirmed the lack of benefit of regular vitamin C supplementation.

Vitamin C did show potential for preventing colds in two specific groups: marathon runners and winter sports athletes (skiers). The reason for this selective effect is unclear, but there is research that shows extreme exercise may depress the immune system. On the other hand, regular moderate aerobic exercise can bolster your protection from common respiratory infections.

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