FactSentinel

Despite its popularity as a cold remedy, vitamin C does not prevent the average person from catching a cold. The most comprehensive evidence comes from a Cochrane systematic review that analyzed dozens of trials involving tens of thousands of participants. It found that regular vitamin C supplementation did not reduce how often people in the general population got colds. Taking it after symptoms begin also has not been shown to make an illness shorter or milder.

The belief traces largely to Nobel laureate Linus Pauling, who promoted high-dose vitamin C in the 1970s. Later controlled research did not support his claims. There are narrow exceptions that keep the myth alive. Regular supplementation produced a modest reduction in cold duration, roughly 8 percent in adults and 14 percent in children, which amounts to less than a day. Among people under extreme physical stress, such as marathon runners, soldiers in subarctic conditions, and skiers, supplementation roughly halved the risk of catching a cold. These groups are not representative of most people.

A common misconception is that more vitamin C always means more protection. The body absorbs only a limited amount, and excess is excreted. Very high doses can cause stomach upset and diarrhea, and may contribute to kidney stones in susceptible people. Vitamin C is an essential nutrient, and deficiency causes real health problems, but getting enough through fruits and vegetables is sufficient for most people. Handwashing, avoiding close contact with sick people, adequate sleep, and vaccination against other respiratory illnesses are better-supported ways to reduce the risk of infection.