Factorial Analysis. Factorial analysis is used to determine the EAR for children ages 4 through 8 years. The nonintestinal endogenous losses and requirement for growth are based on data previously discussed (see “Infants and Children Ages 7 Months through 3 Years”). For this age group, the average intestinal losses are 34 μg/ kg/day of zinc and the amount of new tissue accreted is 7 g/day (Kuczmarski et al., 2000). Based on the summation of zinc losses and requirements for growth, the required amount of absorbed zinc for this age group is approximately 1.2 mg/day (Table 12-4). With a fractional absorption of 0.3 based on studies in infants and young children (Davidsson et al., 1996; Fairweather-Tait et al., 1995), the EAR is 4.0 mg/day of zinc.

Extrapolation from Adults. The average requirement for zinc is 4 mg/day as determined by the method described in Chapter 2, which extrapolates from the adult EAR.

Growth. Some dietary data are available from children aged 4 through 8 years whose growth percentiles were at the lower end of the normal range and who were subjects in placebo-controlled, randomized trials of dietary zinc supplementation. In each of two studies, one in Canada (Gibson et al., 1989) and the other in the United States (Walravens et al., 1983), zinc supplementation was associated with greater linear growth gain. Mean dietary intakes of the placebo-treated controls in the Canadian and U.S. studies were 6.4 and 4.6 mg/day of zinc, respectively. No growth response was observed with zinc supplementation of healthy children of either gender, unselected for growth, whose average calculated zinc intake was 6.3 mg/day (Hambidge et al., 1979a). The SDs were too