Can vitamin C cure a cold? How a Nobel Prize winner convinced us it could

For years, supermarkets and pharmacies have been pushing vitamin C products as a cure for colds and flu season. The story behind this marketing includes Linus Pauling, a Nobel Prize-winning chemist who published a book on vitamin C and colds in 1970. Pauling advocated for high doses of vitamin C, around 1,000–2,000 milligrams per day for health and even more to prevent colds.

However, his advice is based on limited evidence that has since been criticized and widely debunked. Multiple studies have shown that vitamin C's impact on colds, if any, is minimal. In 2023, a meta-analysis of 10 placebo-controlled trials involving 2,736 participants found only a 15% reduction in severe cold symptoms for those taking vitamin C compared to those who didn't.

This reduction was measured in days spent indoors, a limitation acknowledged by the authors. The meta-analysis did not find that vitamin C affected the duration of mild symptoms. Another study from 2013 showed that while regular vitamin C supplementation reduced symptom severity in children and adults by 8–14%, taking it at the start of a cold had no benefit.

Regular vitamin C intake is around the upper limit of what's considered safe, with Australia recommending no more than 1,000mg per day, and the U.S. advising a maximum of 2,000mg. High doses of vitamin C can lead to adverse effects such as gastrointestinal issues, kidney stone risk, increased iron absorption, and drug interactions.

For most people, vitamin C won't prevent colds or reduce symptoms when taken after symptoms start. Regular supplementation may modestly lessen the severity and duration of severe symptoms, with more significant effects observed in athletes and military personnel. While high doses are generally safe for most adults, they can cause side effects.

If you're considering vitamin C supplements, it's best to consult with a healthcare provider and limit your intake to below 1,000mg per day.