EAR, there is likely a need for improved intake. If daily intake is typically between the EAR and the RDA, there is probably a need for improvement because the probability of adequacy, although more than 50 percent, is less than 97.5 percent. However, intakes below the RDA cannot be assumed to be inadequate because the RDA by definition exceeds the actual requirements of all but 2 to 3 percent of the population; many with intakes below the RDA may be meeting their individual requirements (IOM, 2006).

The DRIs are expressed on the basis of reference values for a number of different life stage groups. These life stages have been stipulated generally on the basis of variations in the requirements of all the nutrients under review. A recent IOM report (IOM, 2006) described these general groupings as follows.

Infancy covers the first 12 months of life and is divided into two 6-month intervals. In this report infancy is designated as 0 to 6 months (meaning from birth to 5.9 months or about the first 182 days of life) and as 6 to 12 months (meaning from 6.0 months to 11.9 months or approximately the second 182 days of life). Intake is relatively constant during the first 6 months after birth. That is, as infants grow, they ingest more food; however, on a body-weight basis their intake remains the same. During the second 6 months of life, growth rate slows. As a result, total daily nutrient needs on a body-weight basis may be less than those during the first 6 months of life (IOM, 2005). In general, special consideration was not given to possible variations in physiological need during the first month after birth or to the intake variations that result from differences in milk volume and nutrient concentration during early lactation (IOM, 2005). Specific recommended intakes to meet the needs of formula-fed infants are not set as part of the DRI process.

In terms of height, toddlers experience a faster growth rate compared with older children, and this distinction provides the biological basis for establishing separate recommended intakes for 1- to 3-year-olds compared with 4- to 8-year-olds. However, data on which to base DRIs for toddlers are often sparse; in many cases, DRIs must be derived by extrapolating data taken from the studies of infants or adults.