The common cold, or simply cold, is a viral infectious disease of the upper respiratory tract. The cold is indeed common, and is a significant cause for absences from work and school. Even before the discovery of vitamin C, folklore had it that certain fruits were effective in both preventing and treating the cold. After scientific identification of vitamin C in the early part of the 20th century, research began into the possible effects of the vitamin against the common cold.
Vitamin C has not decreased the frequency of colds in the general population, but it has halved the frequency of colds in people under heavy short-term physical stress. There is no effect of taking vitamin C in doses up to 8 grams per day after a cold has already begun.
Background
Vitamin C was identified in the early part of the previous century and there was much interest in its possible effects on various infections including the common cold. A few controlled trials on the effect of vitamin C on the common cold were carried out already in the 1940s,< but the topic became particularly popular after 1970, when Linus Pauling, a double Nobel laureate, wrote a best-selling book Vitamin C and the Common Cold, advocating that a daily dose of one gram of vitamin C could prevent the common cold. Pauling's book led to great interest in the topic among lay people, but also among academic circles. After Pauling's book, a number of controlled trials were carried out. However, the interest disappeared after the middle of 1970s apparently due to the publication of two reviews and one primary study, which all concluded that vitamin C does not influence the common cold. However, the three papers were later shown to be erroneous.
Research findings
According to the Cochrane review on vitamin C and the common cold, one gram per day or more of vitamin C does not influence common cold incidence in the general community. However, in five randomized double-blind placebo-controlled trials with participants who were under heavy short-term physical stress, vitamin C halved the incidence of colds. In the dose of one gram per day or more, vitamin C shortened the duration of colds in adults by 8% and in children by 18%. Vitamin C supplementation reduced the incidence of colds by half in marathon runners, skiers, or soldiers in subarctic conditions.
See also
- Vitamin C megadosage
- Vitamin C review, Linus Pauling Institute, Oregon State University
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