Dietary Approaches to the Control of Vitamin A Deficiency: An Introduction and Overview

Abstract

As a public health problem, deficiency of vitamin A occurs when the habitual intake of bioavailable vitamin A is too little to meet physiological needs under prevailing conditions. Needs are increased during growth periods and when frequent infections cause inefficient utilization of the vitamin. Historical records and recent experience document that improved dietary intake, even when most vitamin A activity comes from provitamin A carotenoids, can correct the problem, especially when such diets contain adequate fat and the subjects are relieved of heavy worm infestation. An epidemiologic evaluation of the entire food chain, consisting of production, procurement, processing, and consumption, provides the framework for selecting suitable dietary approaches. These approaches include homestead food production, centrally or home-based fortified foods, and educational approaches promoting dietary diversification and modification of preparation practices to conserve the vitamin and render it more bioavailable. Even agricultural approaches that select and propagate germ plasma from varieties with increased micronutrient density can be utilized, including, in the future, genetic modifications to increase micronutrient density of vegetable and staple crops. Usually a mixture of intervention strategies will be most effective, particularly when social marketing accompanies efforts to increase consumer acceptance and compliance. Where the ecological and economic context prohibits dietary approaches, or where acute deficiency necessitates an immediate therapeutic response, distribution of vitamin A supplements is needed until suitable food-based approaches become feasible.