Is it true that you should take vitamin C when you have a cold?

“Vitamin C is important for health in many ways,” says Daniel M. Davis, director of life sciences at Imperial College London. It is a powerful antioxidant that helps protect cells from harmful unstable compounds produced by toxins and pollution. It helps the body absorb iron and is also used in the production of collagen. “But the idea that taking high doses of vitamin C or drinking lots of orange juice prevents you from catching a cold or helps you recover more quickly is a myth.”

Davis, author of Self-defense: a myth-busting guide to immune health (Self-Defense: A Guide to Debunking Immune Health Myths), explains that popular belief in the cold-fighting powers of vitamin C has persisted for more than 50 years, “almost entirely because of the evangelical vision of one man: Linus Pauling.”

Although supplements may slightly reduce the duration of symptoms, the effect is modest.

Pauling, winner of two Nobel Prizes and one of the most influential chemists of the 20th century, contributed significantly to our understanding of vitamins. However, he exaggerated the benefits of vitamin C. In Pauling’s 1970 book, Vitamin C and the common cold (Vitamin C and the Cold), became a bestseller, Davis says, causing demand so high that factories were built to accommodate supplement production.

In fact, research shows that people who take vitamin C supplements are just as likely to get colds as those who don’t. And although supplements may slightly reduce the duration of symptoms (by about 8% in adults), the effect is modest.

“It’s also difficult to interpret this data,” says Davis, “because people who regularly take high doses of vitamin C tend to be more health-conscious in general.”

Instead, he recommends focusing on vitamin D if you want to fight disease. “There’s much clearer evidence that it’s important for immune health,” he says. Vitamin D is obtained through exposure to sunlight between March and October, but the UK National Health Service (NHS) suggests that in winter it is advisable to take it in supplement form.