Do vitamins C and E affect respiratory infections?

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.... Mehr