Interrelationships of key variables of human zinc homeostasis: Relevance to dietary zinc requirements

Currently, estimates of human zinc requirements depend primarily on a facto rial approach. The availability of tracer techniques employing zinc stable isotopes has facilitated the acquisition of data on major variables of zinc homeostasis in addition to those that can be measured with careful metabol ic balance techniques. These data have promising potential to facilitate an d improve the factorial approach. The thesis proposed in this paper is that realistic estimations of dietary zinc requirements by a factorial approach require attention to the dynamic interrelationships between major variable s of zinc homeostasis. This applies especially to the positive relationship between endogenous fecal zinc and total absorbed zinc, which is the essent ial starting point in estimating physiologic and, from there, dietary requi rements.