The Role Of Dietary Zinc Restriction On Antioxidant Status And Oxidative Stress

Abstract

Approximately 10% of the U.S. population consumes less than half the recommended dietary allowance for zinc and are at risk for zinc deficiency. Zinc is a component of over 300 enzymes and has proposed antioxidant function. Consequently, inadequate zinc consumption may lead to enhanced oxidative stress through several mechanisms including altered antioxidant defenses. In the present study, we hypothesized that dietary zinc restriction would result in lower antioxidant status and increased oxidative damage. We fed Sprague Dawley rats (n = 12/group) either a zinc-adequate (50 ppm), zinc-deficient (<0.05 ppm) or pair-fed diet for 4-weeks and then assessed antioxidant status and oxidative stress parameters. Dietary zinc restriction decreased (p<0.05) plasma antioxidant status by 20%, assessed by the ferritin reducing ability of plasma, which was accompanied by a 50% reduction in plasma uric acid (p<0.05), but no significant change in plasma vitamin C concentrations. Zinc restriction did not significantly decrease plasma or hepatic a-tocopherol concentrations, nor were the protein levels of the hepatic a-tocopherol transfer protein altered. However, zinc restriction resulted in lower hepatic g-tocopherol concentrations (p<0.05), which may be explained in part, by increased (p<0.05) hepatic CYP4F2 protein levels. Lastly, zinc restriction resulted in elevated plasma F2-isoprostanes. Collectively, zinc deficiency had differential effects on antioxidant status and may enhance oxidative stress via increased lipid peroxidation and CYP induction.