Vitamin A supplementation: Implications for morbidity and mortality in children

Vitamin A deficiency impairs epithelial integrity and systemic immunity and increases the incidence and severity of infections during childhood. Howev er, findings from vitamin A supplementation trials are not consistent. Supp lementation has resulted in significant reductions in mortality in several (but not all) large community-based trials among apparently healthy childre n. In hospital-based studies, vitamin A supplements have been consistently found to reduce the severity of measles infection, but no effect on nonmeas les respiratory infections has been observed. In some cases, the supplement s were associated with an apparently increased risk of lower respiratory in fection. Vitamin A supplements also reduced the severity of diarrhea in mos t (but not all) trials. Potential explanations for the differences in effic acy across trials are reviewed. While vitamin A supplementation is effectiv e in reducing total mortality and complications from measles infections, it is likely to be more effective in populations suffering from nutritional d eficiencies.