Vitamin C Prophylaxis in a Boarding School

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 J Med 290:6–10, 1974)