in requirements by life stage or gender group, the analysis provided in establishing the DRI for any given nutrient may have been presented for a larger grouping.
Infancy covers the period from birth through 12 months of age and is divided into two 6-month intervals. Except for energy in the macronutrient report, the first 6-month interval was not subdivided further because intake is relatively constant during this time. That is, as infants grow, they ingest more food; however, on a body-weight basis, their intake remains nearly the same. Growth velocity slows during the second 6 months of life, and thus daily nutrient needs on a body-weight basis may be less than needs during the first 6 months of life.
The average intake of nutrients by full-term infants who are born to healthy, well-nourished mothers and who are exclusively fed human milk has been adopted as the primary basis for deriving the AI during the first 6 months of life. The DRI values established are thus not EARs. The extent to which the intake of human milk may result in exceeding the actual requirements of the infant is not known, and ethics of human experimentation preclude testing the levels known to be potentially inadequate. Therefore, the AIs, while determined from the average composition of an average volume of milk consumed by this age group, are not EARs in which only half of the group would be expected to have their needs met.
Using the infant fed human milk as a model is in keeping with the basis for estimating nutrient allowances of infants developed in the last revisions of the RDA (NRC, 1989b) and the RNI (Canada, 1990) reports. It also supports the recommendation that exclusive breast-feeding is the preferred method of feeding for normal, full-term infants for the first 4 to 6 months of life. This recommendation has also been made by the Canadian Paediatric Society (Canada, 1990), the American Academy of Pediatrics (AAP, 1997), and in the FNB report Nutrition During Lactation (IOM, 1991).
In general special consideration was not given to possible variations in physiological need during the first month after birth or to the variations in intake of nutrients from human milk that result from differences in milk volume and nutrient concentration during early lactation. Specific DRIs to meet the needs of formula-fed infants have not been proposed in the DRI reports. The previously published RDAs and RNIs for infants have led to much misinterpre-