Dietary Reference Intakes (DRIs) comprise a set of nutrient-based reference values, each of which has special uses. The development of DRIs expands on the periodic reports, Recommended Dietary Alloxv-ances, which have been published since 1941 by the National Academy of Sciences and the Recommended Nutrient Intakes of Canada. This comprehensive effort is being undertaken by the Standing Committee on the Scientific. Evaluation of Dietary Reference Intakes of the Food and Nutrition Board, Institute of Medicine, National Academies, with the active involvement of Health Canada. See Appendix A for a description of the overall process and its origins.
WHAT ARE DIETARY REFERENCE INTAKES?
The reference values, collectively called the Dietary Reference Intakes (DRIs), include the Estimated Average Requirement (EAR), Recommended Dietary Allowance (RDA), Adequate Intake (AI), and Tolerable Upper Intake Level (UL).
A requirement is defined as the lowest continuing intake level of a nutrient that will maintain a defined level of nutriturc in an individual. The chosen criterion of nutritional adequacy is identified in each chapter; note that the criterion may differ for individuals at different life stages. Hence, particular attention is given throughout this report to the choice and justification of the criterion used to establish requirement values.
This approach differs somewhat from that used by the World Health Organization, Food and Agriculture Organization, and Intcr-
national Atomic Energy Agency (WHO/FAO/IAEA) Expert Consultation on Trace Elements in Human Nutrition and Health (WHO, 1996). That publication uses the term basal requirement to indicate the level of intake needed to prevent pathologically relevant and clinically detectable signs of a dietary inadequacy. The term normative requirement indicates the level of intake sufficient to maintain a desirable body store or reserve. In developing RDAs and AIs, emphasis is placed instead on the reasons underlying the choice of the criterion of nutritional adequacy used to establish the requirement. They have not been designated as basal or normative.
Unless otherwise stated, all values given for EARs, RDAs, and AIs represent the quantity of the nutrient or food component to be supplied by foods from a diet similar to those consumed in Canada and the United States. If the food source of a nutrient is very different (as in diets of some ethnic groups) or if the source is supplements, adjustments may have to be made for differences in nutrient bioavailability. When this is an issue, it is discussed for the specific, nutrient in the section "Special Considerations".
RDAs and AIs arc levels of intake recommended for individuals. They should reduce the risk of developing a condition that is associated with the nutrient in question and that has a negative functional outcome. The DRIs apply to the apparently healthy general population. Meeting the recommended intakes for the nutrients would not necessarily provide enough for individuals who arc already malnourished, nor would they be adequate for certain disease states marked by increased nutritional requirements. Qualified medical and nutrition personnel must tailor recommendations for individuals who arc known to have diseases that greatly increase nutritional requirements or who arc at risk for developing adverse effects associated with higher intakes. Although the RDA or AI may serve as the basis for such guidance, qualified personnel should make necessary adaptations for specific situations
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