Vitamin C and the common cold

Vitamin C, available in tablet or capsule form, is widely used for the prevention or alleviation of the common cold. This practice dates back to the 1970s, though its effectiveness remains difficult to verify.

Linus Pauling's recommendation

Linus Pauling, an American chemist and Nobel Prize winner in chemistry (1954) and the Nobel Peace Prize (1962), proposed the use of vitamin C for the common cold in a book published in 1970. He recommended a daily intake of 1,000 to 2,000 mg for preventive purposes.

Scientific evaluation of vitamin C

Vitamin C does play a role in the immune system, but its effect against the common cold remains unproven. Numerous studies, of varying quality, have been conducted on the subject, with contradictory results.

Cochrane review findings

In 2013, the Cochrane Collaboration reviewed the literature on the subject and concluded that vitamin C has no impact on the occurrence of a cold. Some effects observed were at very high doses, which may not be safe or practical for most people.

Vitamin C as a treatment

As a treatment, vitamin C might reduce the duration of a cold by up to 8 percent, reducing an average 7-day cold to 6.44 days. However, this effect is considered minimal. Starting vitamin C after the onset of a cold is ineffective.

Dietary sources and risks

It is better to focus on dietary intake of vitamin C, which is primarily found in raw or lightly cooked fruits and vegetables. The recommended daily intake corresponds to 2 oranges or 200 grams of strawberries. Supplementation beyond this is not very relevant, as excess vitamin C is excreted and may be metabolized into oxalate, increasing the risk of kidney stones.