Except for iron and zinc, during the period of infant growth and gradual weaning to a mixed diet of human milk and solid foods from ages 7 through 12 months, there is no evidence for markedly different nutrient needs. The AI can be derived for this age group by calculating the sum of (1) the content of the nutrient provided by 0.6 L/day of human milk, which is the average volume of milk reported from studies of infants receiving human milk in this age category (Heinig et al., 1993) and (2) that provided by the usual intakes of complementary weaning foods consumed by infants in this age category. Such an approach is in keeping with the current recommendations of the Canadian Paediatric Society (Health Canada, 1990), the American Academy of Pediatrics (AAP, 1997), and the Institute of Medicine (IOM, 1991) for continued feeding of infants with human milk through 9 to 12 months of age with appropriate introduction of solid foods. The amounts of vitamin A, copper, iron, and zinc consumed from complementary foods were determined by using Third National Health and Nutrition Examination Survey data, and they are discussed in the nutrient chapters.
For some of the nutrients, two other approaches were considered as well: (1) extrapolation downward from the EAR for young adults by adjusting for metabolic or total body size and growth and adding a factor for variability and (2) extrapolation upward from the AI for infants ages 0 through 6 months by using the same type of adjustment. Both of these methods are described below. The results of the methods are compared in the process of setting the AI.
Human milk does not provide sufficient levels of iron and zinc for proper growth and development of the older infant. Because factorial data were available for iron and zinc in the older infants, an EAR for iron and zinc has been established for infants ages 7 through 12 months.
For vitamin A, chromium, copper, iodine, and molybdenum, data were not available to set the EAR and Recommended Dietary Allowance (RDA) or an AI for children ages 1 year and older and adolescents. Therefore, the EAR or AI has been extrapolated down by