Approaches to Recommended Intakes for Infants

The AI was initially created for infants, where it would be unethical to intentionally feed infants varying levels of intake known to be deficient and evaluate changes in body weight, growth, or other nutritional status indicators over time. Also of concern was the tendency seen with past reference standards for inaccurate comparisons to be made between recommended intakes and human milk composition. Human milk was frequently cited as inadequate for a number of nutrients. To eliminate this misinterpretation, AIs based on the nutrient content of human milk are provided for infants for nutrients for which there is no evidence indicating that breast-fed infants should have supplementary amounts above that provided in human milk [8].

The AIs for infants are calculated by estimating an average volume of intake by healthy, full-term, exclusively breast-fed infants midway through the first 6 months or the second 6 months of life. The amount of a nutrient in that volume is estimated from analysis of human milk samples taken during the same time period of infant feeding (2-6 or 7-12 months of lactation). During the second 6 months of life, the estimated contribution of complementary foods is added to the average amount of the nutrient provided by human milk. The values should be used in context; the DRI reports point out that there will be variation in both the amount consumed and its composition during normal infancy, and thus the computed values represent average values, noting that it is expected that infants will consume increased volumes of human milk as they grow.

While separate recommendations for infants fed formula are not made, if specific issues relative to bioavailability or the source of a nutrient are relevant to developing an optimal formula, the issue is discussed and data provided for modifying the recommended intake. Because of the reliance on human milk composition, the AI is less than previous recommended intakes for infants in the US [3] or Canada [14].

Of the nutrients reviewed as part of the DRI process, two nutrients were considered inadequate in the diets of infants beyond their 6th month of life when fed exclusively human milk: iron and zinc [12]. Using a factorial method to estimate average requirements that includes amounts for growth, EARs were developed for these two nutrients for infants 7-12 months of age, resulting in the only RDAs provided for this age group.

Because of organ immaturity, no ULs were established for infants, with the statement that infants should obtain nutrients from food (including human milk) or formula only.

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