The formula for the extrapolation is

EARchild = EARadult (F),

where F = (Weightchild/Weightadult)0.75 (1 + growth factor). Reference weights from Table 1-1 are used. If the EAR differs for men and women, the reference weight used for adults in the equation differs by gender; otherwise, the average for men and women is used unless the value for women is derived from data on men. The approximate proportional increase in protein requirements for growth (FAO/WHO/UNA, 1985) is used as an estimate of the growth factor as shown in Table 3-1. If only an AI has been set for adults, it is substituted for the EAR in the above formula, and an AI is calculated; no RDA is set.

Setting the RDA for Children

To account for variability in requirements because of growth rates and other factors, a 10 percent coefficient of variation (CV) for the requirement is assumed unless data are available to support another value, as described in Chapter 1.

Method for Extrapolating Data from Young to Older Infants

This adjustment, the metabolic weight ratio method, involves metabolic scaling but does not adjust for growth because it is based on a value for a growing infant. To extrapolate from the AI for infants ages 0 through 6 months to an AI for infants ages 7 through 12 months, the following formula is used:

AI7–12 mo = AI0–6 mo (F),

where F = (Weight7–12 mo/Weight0–6 mo)0.75.

TABLE 3-1 Estimated Growth Factor by Age Group

Age Group

Growth Factor

7 mo–3 y


4–8 y


9–13 y


14–18 y






SOURCE: Proportional increase in protein requirements for growth from FAO/WHO/UNA (1985) used to estimate the growth factor.

The National Academies of Sciences, Engineering, and Medicine
500 Fifth St. N.W. | Washington, D.C. 20001

Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement