Micronutrient regulation in pregnant and lactating women from Rio de Janeiro.

Studies with low-income pregnant and lactating women from the city of Rio de Janeiro, concerned mainly with the changes in micronutrient homeostasis during pregnancy and lactation in the absence of overt clinical deficiencies, are reported. These studies focused on folate, cobalamin, iron, zinc and vitamin A. Factors that may affect the maternal micronutrient state, such as dietary intakes, use of supplements and interrelationships of micronutrients have been considered, as well as the implications of these changes for maternal-fetal transfer and milk composition. Although these studies were not designed to evaluate the prevalence of sub-clinical micronutrient deficiencies in pregnant and lactating women, they indicate that high frequencies of sub-clinical deficiencies of folate, iron, zinc and vitamin A, especially in pregnant women, are expected to be found in Rio de Janeiro.