Thus, after careful review and analysis of the evidence, including examination of the extent of congruent findings, scientific judgment was used to determine the basis for establishing the values. The reasoning used is described for each nutrient in Chapter 5, Chapter 6, Chapter 7 through Chapter 8.

Pathways to Nutrient Requirements

The possible pathways that were considered in determining the requirement for each nutrient include the following:

  1. The availability of a convincing totality of evidence, including randomized clinical trial data, that the nutrient reviewed reduces the risk of important health outcomes—demonstration that a biomarker of exposure influences a specific health outcome constitutes a key component of this body of evidence.

  2. The availability of a convincing totality of evidence, including randomized clinical trial data, that the nutrient reviewed favorably affects a selected functional marker—this pathway was used with caution in view of the many examples where intervention effects on an intermediate outcome (biomarker) proved to be inconsistent with intervention effects on the chronic disease of interest.

  3. The presence of a clinically important deficiency disease or nutritional syndrome that has been demonstrated to relate specifically to an inadequate intake of the nutrient reviewed—this pathway is facilitated by considering intakes needed to ensure adequate body stores or reserves of the nutrient or of pertinent compounds that the body produces in response to adequate intake of the nutrient.

Method to Determine the Adequate Intake for Infants

The AI for young infants is generally taken to be the average intake by full-term infants who are born to apparently healthy, well-nourished mothers and are exclusively fed human milk. The extent to which the intake of a nutrient from human milk may exceed the actual requirements of infants is not known, and the ethics of experimentation preclude testing the levels known to be potentially inadequate. Using the infant exclusively fed human milk as a model is in keeping with the basis for earlier recommendations for intake (e.g., Health Canada, 1990; IOM, 1991). It also supports the recommendation that exclusive intake of human milk 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 Cana-

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