Vitamin A: A Review

This study provides a comprehensive review on the fat-soluble micronutrient vitamin A, changes in its status among vulnerable groups of different populations and the results of experience with different strategies/interventions designed to improve its status. Vitamin A can be derived from animal sources (preformed in liver, milk, eggs, fatty fish) or plant sources (in fruits and vegetables as provitamin A). The vitamin is required for normal growth and development, playing a part in reproduction, differentiation of cellular epithelium, regulation of cell division, genetic regulation and enhancement of immune responses. Retinol (its basic molecule) is metabolised into a number of biologically active retinoid compounds, such as retinal (active element of visual pigment) and retinoic acid, an intracellular messenger that modulates cell differentiation. Uneven distribution of natural sources of vitamin A, low dietary intake of animal products, the traditional technological transformation/processing of foods, low absorption and limited bioconversion of carotenoids may impact negatively on vitamin A activity. Vitamin A deficiency (VAD), a major public health nutritional problem in many developing countries, results in a range of developmental and pathological states with consequences ranging from potentially blinding xerophthalmia to increased risks of infection and mortality. All alternatives employed towards eradicating VAD (nutrition education, dietary diversification, dietary supplementation and food fortification) have provided a high return on investment in terms of disability-adjusted-life years gained. Key options for action, as well as important areas of research are being discussed. Control of VAD will lead to a substantial improvement in childhood survival and prevent the scandal of irreversible blindness. It is suggested that early introduction of children to abundant natural sources of vitamin A (like red palm oil-prepared meals) be encouraged.