Vitamin C intake and susceptibility to the common cold

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Hemilä , H 1997 , ' Vitamin C intake and susceptibility to the common cold ' , British Journal of Nutrition , vol. 77 , no. 1 , pp. 59-72 .

Title: Vitamin C intake and susceptibility to the common cold
Author: Hemilä, Harri
Contributor organization: Department of Public Health
Date: 1997
Language: eng
Number of pages: 14
Belongs to series: British Journal of Nutrition
ISSN: 0007-1145
Abstract: Although the role of vitamin C in common cold incidence had been studied extensively, the level of vitamin C intake has not been unequivocally shown to affect the incidence of colds. In the present study the six largest vitamin C supplementation (> or = 1 g/d) studies, including over 5000 episodes in all, have been analysed, and it is shown that common cold incidence is not reduced in the vitamin C-supplemented groups compared with the placebo groups (pooled rate ratio (RR) 0.99; 95% CI 0.93, 1.04). Consequently these six major studies give no evidence that high-dose vitamin C supplementation decreases common cold incidence in ordinary people. Nevertheless, the analysis was continued with the hypothesis that vitamin C intake may affect common cold susceptibility in specific groups of people. It was assumed that the potential effect of supplementation might be most conspicuous in subjects with low dietary vitamin C intake. The average vitamin C intake has been rather low in the UK and plasma vitamin C concentrations are in general lower in males than in females. In four studies with British females vitamin C supplementation had no marked effect on common cold incidence (pooled RR 0.95; 95% CI 0.86, 1.04). However, in four studies with British male schoolchildren and students a statistically highly significant reduction in common cold incidence was found in groups supplemented with vitamin C (pooled RR 0.70; 95% CI 0.60, 0.81). Thus, these studies with British males indicate that vitamin C intake has physiological effects on susceptibility to common cold infections, although the effect seems quantitatively meaningful only in limited groups of people and is not very large.
Subject: ascorbic acid
upper respiratory-tract infection
common cold
controlled trials
Peer reviewed: Yes
Usage restriction: openAccess
Self-archived version: publishedVersion

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