Vitamin C helps with colds

Cochrane

The common cold is one of the most common causes of doctor visits and absenteeism from work and school in high-income countries. There are more than 200 viruses that cause cold symptoms such as a runny or stuffy nose, sneezing, sore throat, cough, and sometimes headache, fever, and red eyes. The symptoms vary from person to person and from cold to cold. Since the common cold is usually caused by one of the respiratory viruses, antibiotics won't work in this case; other treatment options are therefore of great interest to the healthcare sector.

Vitamin C has been mentioned as a treatment for respiratory infections since it was isolated in the 1930s. It was particularly popular in the 1970s, when the Nobel Prize winner Linus Pauling concluded from earlier placebo-controlled studies that vitamin C prevents colds and alleviates symptoms. More than two dozen new studies were then carried out. Vitamin C has been sold and used all over the world as a preventive and therapeutic agent.

This review is limited to placebo-controlled studies that investigated vitamin C at a dose of 0.2 g / day or more. Regular intake of vitamin C had no effect on the incidence of colds in the normal population, comparing 29 studies with 11,306 participants. However, regular supplementation had a modest but consistent effect in reducing the duration of cold symptoms; We came to this result through 31 comparisons reported in studies with 9745 cold episodes (episode = single occurrence). In 5 studies with 598 participants who were exposed to extreme physical stress over short periods of time (including marathon runners and skiers), vitamin C halved the risk of colds. The published studies did not report any adverse effects of vitamin C.

Studies in which high doses of vitamin C were given as treatment after symptoms appeared did not show a consistent effect on the duration or severity of cold symptoms. However, few treatment studies have been conducted and none of them have examined children, although the effects of preventive vitamin C in children were stronger. One large study in adults reported a benefit of the 8 g treatment dose at the onset of symptoms, and 2 treatment studies in which vitamin C was given for 5 days also reported a benefit. Further studies are needed to clarify the possible role of therapeutic vitamin C administration, i.e. administration immediately after the onset of symptoms.