VITAMIN-A AS AN IMMUNOMODULATING AGENT

Findings on the benefits and mechanism of action of vitamin A in measl es and other infectious diseases and immunocompromised states are disc ussed. Vitamin A deficiency is one of the world's major malnutrition p roblems and is most commonly found in children under the age of five y ears. An association between vitamin A status and immune function has been suggested by community studies and animal experiments. Mortality and susceptibility to infection and diarrhea are higher in children wi th vitamin A deficiency. The association between increased mortality a nd morbidity and vitamin A deficiency is strongest in children with me asles. Vitamin A supplementation reduces mortality and complications r esulting from measles. Measles may increase the body's utilization of vitamin A, possibly because of the rapid destruction of epithelial sur faces. Vitamin A may boost immune responses in the elderly, persons wi th high exposure to ultraviolet light, patients who have undergone sur gery, and persons with parasitic infection, but more studies are neede d. The immune defect caused by vitamin A deficiency may be due to alte rations in the glycoproteins of the lymphocyte membrane, an adverse ef fect on helper T-cell function, the effect on epithelial tissue, or so me other mechanism. Vitamin A therapy is relatively safe, and its effe ctiveness in children with measles and possibly other groups appears t o justify public health campaigns to eliminate vitamin A deficiency. V itamin A apparently has important immunomodulating properties, notably in patients with measles.