RDA is not intended to be used to assess the diets of either individuals or groups or to plan diets for groups.

Adequate Intakes

The Adequate Intake (AI) is set instead of an RDA if sufficient scientific evidence is not available to calculate an EAR. For example, the AI for young infants, for whom human milk is the recommended sole source of food for most nutrients up through the first 4 to 6 months, is based on the daily mean nutrient intake of apparently healthy, full-term infants who receive only human milk. The main intended use of the AI is as a goal for the nutrient intake of individuals. Other uses of AIs will be considered in future reports.

Comparison of RDAs and AIs

Although both the RDA and the AI are to be used as a goal 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. However, because no distribution of requirements is known for nutrients with an AI, it is not possible to know what percentage of individuals are covered by the AI. In determining the AI for a nutrient, it is expected to exceed the RDA for that nutrient, if it were known, and should cover the needs of more than 97 to 98 percent of the individuals (see Figure S-1). The degree to which an AI exceeds the RDA is likely to differ among nutrients and population groups, however.

For people with diseases that increase specific nutrient requirements or those 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.

Table S-1, Table S-2 through Table S-3 give the recommended intake levels, whether RDAs or AIs, for vitamin C, vitamin E (α-tocopherol), and selenium by life stage and gender group. For these nutrients, AIs rather than RDAs are being proposed for infants to age 1 year.

Tolerable Upper Intake Levels

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

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