Abstract
Humans need vitamin A for such essential processes as growth, vision, and resistance to infectious disease. Vitamin A deficiency (VAD) arises from prolonged inadequate intake combined with periods of higher physiological demand, such as during childhood growth spurts, pregnancy, and lactation, or through increased utilization during infection (Sommer and West 1996). Thus, young children and pregnant and lactating women are at greatest risk and are the most common victims. It occurs primarily among people with limited food choices, particularly those in the lower socioeconomic strata of poor countries with diets predominated by less nutritious staple foods (Sommer and West 1996).
