Malnutrition, brain development, learning, and behavior

Three widely prevalent nutritional deficiencies are recognized to have the potential for permanent adverse effects on learning and behavior: protein-energy, iron, and iodine. Supplementation with adequate protein and calories during the first two years of life improves the cognitive performance of poorly nourished children, and the benefits may be even more robust years later when the children become adolescents and young adults. Iron deficiency is the most common global nutritional problem; among the earliest functions to be affected are those associated with the brain enzymes involved in cognition and behavior. The effects of iron deficiency during infancy appear to be irreversible. At older ages iron deficiency is intellectually and educationally disadvantageous independently of ethnicity and of physical and social environment. Even in areas where cases of cretinism due to iodine deficiency in the mother are few, the linear growth of the infant, its intellectual capacity, and certain other of its neurological functions are permanently compromised to varying degrees. In addition to these three most prevalent forms of deficiency, recent evidence suggests that cow's milk and infant formulas may lack sufficient omega-3 fatty acids for optimal development of the preterm infant and the neonate. Nutritional deficiencies are also potential contributors to impaired cognition in the elderly. Investments in education and community development would be more effective if the physical and cognitive capacity of underprivileged populations were not impaired by malnutrition. (C) 1998 Elsevier Science Inc.