the short summaries in this paper are oversimplified and cannot do justice to the relevant controversies or the limitations of the available studies; and (3) we emphasize national data sets wherever possible, but nationally representative samples are not available for some important indicators.

The lower scores on tests of cognitive functioning and poorer school achievement of many minority children have received considerable attention. Results from the Third National Health and Nutrition Examination Survey (NHANES III) show that Black and Mexican children, compared to Whites at all levels of family income, receive lower scores on subtests of an IQ scale and on reading and writing achievement tests (Figure 12–1) (Kramer et al., 1995). These test results, combined with their correlates in poor school achievement, mean that the country is losing important human capacity.

Perinatal problems and poor nutrition in infancy contribute to poorer behavioral and developmental outcomes. The rapid growth of the brain in the early years, and the development of fundamental mental and motor processes, make infancy a particularly vulnerable period. Despite the plasticity of the brain, children who experience early biologic insults and stressors are at higher risk for long-lasting behavioral and developmental disturbances. Although considerations of lower test scores and poorer school achievement may acknowledge the role of health and nutrition, specific information is often not incorporated into the discussion; yet this is an issue for which there is nationally representative data, showing major racial differences in the prevalence of common early biologic risks. For some of these problems, there is also evidence that dramatic changes can occur when the country identifies a problem, makes the commitment to improve the situation, and dedicates the necessary resources.

On a worldwide basis, iron deficiency is the most common single-nutrient disorder. Dietary iron deficiency develops relatively slowly, and anemia is a late manifestation. Infants are at particularly high risk because they grow so rapidly and there are limited sources of iron in the infant diet. Approximately one in five babies (0 to 2 years old) in the world has iron-deficiency anemia, and an even higher percentage have iron deficiency without anemia (deMaeyer et al., 1985; Florentino and Guirriec, 1984).