Society (Health Canada, 1990), the American Academy of Pediatrics (AAP, 1997), and the Institute of Medicine (IOM, 1991) for continued feeding of infants with human milk through 9 to 12 months of age, with appropriate introduction of solid foods. Selenium and vitamin C had published information about the intake from solid foods for infants aged 7 through 12 months, and thus followed this method.
For vitamin E, which did not have intake data from solid foods, the AI was calculated by extrapolating upward from the AI for infants ages 0 through 6 months, adjusting for metabolic body size and growth, and adding a factor for variability. The method is described below.
For vitamin C, vitamin E, and selenium, data were not available to set the EAR and RDA for children ages 1 year and older and adolescents. Because vitamin C is a water-soluble vitamin and boys have a larger lean body mass and total body water than girls, the adult EAR was adjusted for children and adolescents on the basis of differences in reference weights from Table 1-1. For vitamin E and selenium, the EAR has been extrapolated downward using an adjustment for metabolic body size and growth. The method relies on at least four assumptions:
Maintenance needs for vitamin E and selenium expressed with respect to body weight ([kilogram of body weight]0.75) are the same for adults and children. Scaling requirements to the 0.75 power of body mass adjusts for metabolic differences demonstrated to be related to body weight, as described by Kleiber (1947) and explored further by West et al. (1997). By this scaling, a child weighing 22 kg would require 42 percent of what an adult weighing 70 kg would require—a higher percentage than if the requirement were based on body weight to a power of one.
The EAR for vitamin E and selenium for adults is an estimate of maintenance needs.
The percentage of extra vitamin E and selenium needed for growth is comparable with the percentage of extra protein needed for growth.
On average, total needs do not differ substantially for males compared to females until age 14, when reference weights differ.