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of food that may not meet the traditional concept of a nutrient but are of possible benefit to health will be reviewed, and if sufficient data exist, reference intakes will be established.

Where adequate information is available, each nutrient has a set of DRIs. A nutrient has either an Estimated Average Requirement (EAR) and an RDA, or an Adequate Intake (AI). When an EAR for the nutrient cannot be determined (and therefore, neither can the RDA), then an AI is set for the nutrient. In addition, many nutrients have a Tolerable Upper Intake Level (UL). A brief definition of each of the DRIs is presented in Box S-1.

Like the former RDAs and RNIs, each DRI refers to the average daily nutrient intake of apparently healthy individuals over time. The amount of intake may vary substantially from day to day without ill effect in most cases.

The chosen criterion of nutritional adequacy or adverse effect on which the DRI is based is different for each nutrient and is identified in the DRI nutrient reports. In some cases the criterion for a nutrient may differ for individuals at different life stages. In developing recommendations, emphasis is placed on the reasons underlying the particular criterion of adequacy used to establish the requirement for each nutrient. This requirement is typically presented as a single number for various life stage and gender groups rather than as multiple endpoints even if the criterion of adequacy for the endpoint

Box S-1 Dietary Reference Intakes

Estimated Average Requirement (EAR): the average daily nutrient intake level estimated to meet the requirement of half the healthy individuals in a particular life stage and gender group.

Recommended Dietary Allowance (RDA): the average daily nutrient intake level sufficient to meet the nutrient requirement of nearly all (97 to 98 percent) healthy individuals in a particular life stage and gender group.

Adequate Intake (AI): a recommended average daily nutrient intake level based on observed or experimentally determined approximations or estimates of nutrient intake by a group (or groups) of apparently healthy people that are assumed to be adequate—used when an RDA cannot be determined.

Tolerable Upper Intake Level (UL): the highest average daily nutrient intake level likely to pose no risk of adverse health effects to almost all individuals in the general population. As intake increases above the UL, the potential risk of adverse effects increases.

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