for most nutrients if special outside factors do not apply. In all cases, the method used to derive the RDA from the EAR is stated.
Together with an estimate of the variance of intake, the EAR may also be used in the assessment of the intake of groups or in planning for the intake of groups (Beaton, 1994) (see Chapter 9).
If sufficient scientific evidence is not available to calculate an EAR, a reference intake called an Adequate Intake (AI) is used instead of an RDA. The AI2 is a value based on experimentally derived intake levels or approximations of observed mean nutrient intakes by a group (or groups) of healthy people. In the opinion of the DRI Committee, the AI for children and adults is expected to meet or exceed the amount needed to maintain a defined nutritional state or criterion of adequacy in essentially all members of a specific healthy population. Examples of defined nutritional states include normal growth, maintenance of normal circulating nutrient values, or other aspects of nutritional well-being or general health.
The AI is set when data are considered to be insufficient or inadequate to establish an EAR on which an RDA would be based. For example, for young infants for whom human milk is the recommended sole source of food for most nutrients for the first 4 to 6 months, the AI is based on the daily mean nutrient intake supplied by human milk for healthy, full-term infants who are exclusively breastfed. For adults, the AI may be based upon review of data from different approaches (e.g., dietary and experimental intakes of calcium) that each alone do not permit a reasonably confident estimate of an EAR.
The issuance of an AI is an indication that more research is needed to determine, with some degree of confidence, the mean and distribution of requirements for a specific nutrient. When this research is completed, it should be possible to replace AI estimates with EARs and RDAs.
It should be emphasized that the AI is different from both the RDA as defined here and from the “lower limit of the population mean intake range for nutritional sufficiency” used in the WHO report Trace Elements in Human Nutrition and Health (1996), which are each derived from information about the EAR.