During the second 6 months of life, growth velocity slows, and thus total daily nutrient needs on a body weight basis may be less than those during the first 6 months of life.
For a particular nutrient, average intake by full-term infants who are born to healthy, well-nourished mothers and exclusively fed human milk has been adopted as the primary basis for deriving the AI for most nutrients during the first 6 months of life. The value used is thus not an EAR; the extent to which intake of human milk may result in exceeding the actual requirements of the infant is not known, and ethics of experimentation preclude testing the levels known to be potentially inadequate. Therefore, the AI is not an estimated average requirement in which only half of the group would be expected to have their needs met.
Using the human milk-fed infant as a model is in keeping with the basis for estimating nutrient allowances of infants developed in the last RDA (NRC, 1989a) and RNI (Health Canada, 1990) reports. It also supports the recommendation that exclusive breastfeeding is the preferred method of feeding for normal full-term infants for the first 4 to 6 months of life. This recommendation has been made by the Canadian Paediatric Society (Health Canada, 1990), the American Academy of Pediatrics (1982) and in the FNB report Nutrition During Lactation (IOM, 1991).
In general, for this report, special consideration was not given to possible variations in physiological need during the first month after birth (when, for example, urinary phosphorus loss is lower due to immature glomerular filtration rate [Brodehl et al., 1982; Svenningsen and Lindquist, 1974]) 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 are not proposed in this report. The previously published RDAs and RNIs for infants have led to much misinterpretation of the adequacy of human milk because of a lack of understanding about their derivation for young infants. Although they were based on human milk composition and volume of intake, the previous RDA and RNI values allowed for lower bioavailability of nutrients from nonhuman milk. In order to assist in deriving appropriate intakes of infants fed foods other than human milk, considerations for applying the AIs to formulas are addressed under the “Special Considerations” sections in Chapter 4, Chapter 5, Chapter 6, Chapter 7 through Chapter 8.
Ages 0 through 6 Months. To derive the AI value for infants ages 0 through 6 months, the mean intake of a nutrient was calculated based on the average concentration of the nutrient from 2 through