Vitamin A supplements and diarrheal and respiratory tract infections among children in Dar es Salaam, Tanzania.

OBJECTIVE: To determine the effect of vitamin A supplementation on the risk of diarrhea and of acute respiratory infection. DESIGN: Double-blind, randomized, placebo-controlled trial. SETTING: Dar-es-Salaam, Tanzania. SUBJECTS: Six hundred eighty-seven children, 6 to 60 months old, hospitalized with pneumonia, who received vitamin A or placebo at baseline and at 4 and 8 months after discharge from hospital. MAIN OUTCOME VARIABLES: Incidence and duration of episodes of diarrhea and respiratory tract infections during the year after discharge from the hospital. RESULTS: Relative to those receiving placebo, children receiving vitamin A had a significantly smaller risk of severe watery diarrhea (multivariate odds ratio = 0.56, 95% CI = 0.32-0.99, P =.04) but a higher risk of cough and rapid respiratory rate (multivariate odds ratio = 1.67, 95% CI = 1.17-2.36, P =.004). Vitamin A supplementation was also associated with increased risk of acute diarrhea among normally nourished children or children with stunted growth but was relatively protective among children with wasting disease (P value for interaction =.01). The apparently increased risk of respiratory tract infection was limited to children who were seronegative for human immunodeficiency virus (HIV) (P value for interaction =.07). CONCLUSIONS: Vitamin A supplements provide a low-cost intervention against morbidity in HIV-infected and undernourished children. Supplements may also have serious non-lethal adverse outcomes in well-nourished individuals. Whether these apparent detrimental effects of vitamin A are transient or long-term needs to be examined.