Vitamin C Prophylaxis in a Boarding School

Abstract

A double-blind study to evaluate vitamin C supplements for respiratory-infection prophylaxis was conducted among 641 children at a Navajo boarding school over a 14-week period. Supplements of 1 and 2 g, or placebo, were given daily. A sample of each group had serial blood ascorbic acid determinations, which showed significant rises among groups treated with vitamin C, but no difference in mean levels between those receiving 1 and those given 2 g. Although there was no difference between treatment groups in number of respiratory episodes, those given vitamin C had fewer days of morbidity than those receiving placebo, both in older (34 per cent) and in younger (28 per cent) age groups. In active surveillance, there were 26 per cent fewer symptomatic days observed in younger vitamin C groups, and 33 per cent fewer in older girls on vitamin C. No such difference was seen in older boys. Nasal discharge and cough-were the two symptoms apparently benefited. Significantly more children on vitamin C had no sick days observed in the periodic survey. In addition, treated children with higher blood ascorbic acid levels had fewer symptomatic days noted than those with lower levels. (N Engl

Vitamin C supplementation and common cold symptoms: factors affecting the magnitude of the benefit

“…In two studies with children, the vitamin C level in plasma (18) and urine (25) increased in subjects given a placebo (sic!) suggesting that tablets were exchanged by playful children.…”

“…The previous searches were extended by MEDLINE searches to identify newer vitamin C-common cold trials. All placebo-controlled studies using regular vitamin C supplementation with 1 g/day of the vitamin were selected for the present quantitative analysis (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31), and the results are shown in Table 1. Regular supplementation refers here to initiating supplementation with healthy people and continuing over the occurring common cold episodes.…”

“…In two trials (18,22) different vitamin C doses were given to separate groups within the same study. Because of the similarity of subjects and the constant outcome definition across the study groups, these two trials are more pertinent to the question of dose-dependency than the comparison of means of dissimilar studies.…”

Vitamin C supplementation and common cold symptoms: Problems with inaccurate reviews

“…Thus, important elements of Coulehan's (9) results were explicitly published and can be statistically re-analyzed, in contrast to Dykes and Meier's claims. Furthermore, Coulehan et al (9) found that the duration of colds was 12% and 29% shorter in children administered 1 and 2 g/d of vitamin C respectively suggesting dose dependency up to 2 g/d, but these data were not given by Dykes and Meier (24).…”

“…(24) commented on Coulehan's 1974 study (9) of schoolchildren: "Because the data required for an appropriate analysis are not presented, the statistical significance of the differences reported cannot be considered to have been established." However, Coulehan et al (9) explicitly reported that 32% (61 of 190) of lower grade children administered vitamin C were "never ill on active surveillance," while only 16% (30 of 192) of those administered placebo were never ill. It is highly unlikely that such a difference in favor of vitamin C would be caused purely by chance (P = 0.0002; 2-tailed Fisher's exact test).…”