FIGURE 12-2 Asymptotic regression of absorbed zinc and ingested zinc. Individual points are means for the same data sets in Figure 12-1. SOURCE: Hunt JR et al. (1992), Jackson et al. (1984), Lee et al. (1993), Taylor et al. (1991), Turnlund et al. (1984, 1986), Wada et al. (1985).

First, confirmation of the effect of zinc supplements on growth velocity (linear growth and weight) in children with varying degrees of growth retardation has been shown in a number of studies from many countries (Brown et al., 1998; Umeta et al., 2000). Second, because a sufficient number of these studies have been undertaken in North America, growth is applicable as a functional/clinical indicator of zinc requirement in North American children (Gibson et al., 1989; Walravens and Hambidge, 1976; Walravens et al., 1983, 1989). Third, baseline dietary data typically included in these studies are adequate to use for group analyses.

Strong positive correlations have been observed between dietary zinc content, especially the amount of absorbed zinc, and estimates of the size of the combined pools of zinc that exchange with zinc in