Synopsis

Regular vitamin C supplementation shortens the

duration of common cold infections.

Although vitamin C has no preventive effect in the

general community, it may reduce the incidence of

respiratory symptoms in restricted population groups

such as people under acute physical stress and

people with a particularly low dietary intake of

vitamin C. Given the reported benefits, it is

puzzling that major textbooks have rejected the

possibility that vitamin C might be beneficial

against colds. In this study, it is shown that the

most influential reviews on vitamin C and the common

cold, cited in the major textbooks, contain numerous

errors. Vitamin E supplementation has no overall

effect on the incidence of the common cold or

pneumonia, but in the case of both infections a

substantial modification of the vitamin E effect was

found. A major finding in this study is

heterogeneity in the effects of vitamin C and

vitamin E. While there is no evidence that ordinary

people might benefit from supplementation, the

heterogeneity indicates that further study should be

carried out to identify the conditions in which

these vitamins might be beneficial.