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ever, if adverse effects have been associated with intake from supplements or food fortificants only, the UL is based on nutrient intake from those sources only, not on total intake. The UL applies to chronic daily use.

For some nutrients, there are insufficient data on which to develop a UL. This does not mean that there is no potential for adverse effects resulting from high intake. When data about adverse effects are extremely limited, extra caution may be warranted.

COMPARISON OF RECOMMENDED DIETARY ALLOWANCES AND ADEQUATE INTAKES

Although the Recommended Dietary Allowance (RDA) and Adequate Intake (AI) are used for the same purpose—setting goals for intake by individuals—the RDA differs from the AI. Intake of the RDA for a nutrient is expected to meet the needs of 97 to 98 percent of the individuals in a life stage and gender group. If the EAR is not known, as is the case when an AI is set, it is not known what percentage of the individuals are covered by the AI. The AI for a nutrient is expected to exceed the average requirement for that nutrient, and it might even cover the needs of more than 98 percent of the individuals, but it might cover the needs of far fewer (see Figure S-1). The degree to which an AI exceeds the average requirement is likely to differ among nutrients and population groups.

For people with diseases that increase requirements or who have other special health needs, the RDA and AI may each serve as the basis for adjusting individual recommendations; qualified health professionals should adapt the recommended intake to cover higher or lower needs.

In this report, AIs rather than RDAs are being proposed for all nutrients for infants to age 1 year and for pantothenic acid, biotin, and choline for persons of all ages (see Table S-1).

APPROACH FOR SETTING DIETARY REFERENCE INTAKES

The scientific data used to develop DRIs have come from observational and experimental studies. Studies published in peer-reviewed journals were the principal source of data. Life stage and gender were considered to the extent possible, but for some nutrients the data did not provide a basis for proposing different requirements for men and women or for adults in different age groups.

Three of the categories of reference values (Estimated Average Requirement [EAR], Recommended Dietary Allowance [RDA], and



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