EXTRACELLULAR-SUPEROXIDE DISMUTASE ACTIVITY IS AFFECTED BY DIETARY ZINC INTAKE IN NONHUMAN PRIMATE AND RODENT MODELS

Assessment of zinc nutriture is often compromised by the lack of relia ble biomarkers. In the present study the effect of dietary zinc depriv ation on plasma extracellular superoxide dismutase (EC SOD) activity w as investigated in rat and rhesus macaque models. This enzyme, which c ontains both zinc and copper, is distinct from cytosolic copper-zinc S OD. Young, growing rats fed zinc-deficient diets (1.5 nmol Zn/g diet) were characterized by low plasma zinc concentrations and plasma EC SOD activities (16% and 56% of controls, respectively). Adolescent rhesus macaques fed diets that contained a marginal amount of zinc (30.6 nmo l Zn/g diet) also had low plasma zinc concentrations and low EC SOD ac tivities compared with controls fed diets containing 765 nmol Zn/g die t (75% and 40%, respectively). Enzyme activity was not affected after in vitro addition of zinc to plasma samples from control, restrict-fed , and zinc-deficient rats. Taken together, these data support the conc ept that plasma EC SOD activity can be a biomarker for zinc status.