Submitted to: Federation of American Societies for Experimental Biology Conference
Publication Type: Abstract Only
Publication Acceptance Date: April 30, 1998
Publication Date: N/A
Technical Abstract: Twelve postmenopausal women aged 55-76 y completed a metabolic unit study to investigate the effects of low and moderately high zinc intakes on copper and iron nutriture. After a 10 d equilibration period, half the women were fed a diet containing 1 mg Cu/2000 kcal and the rest were fed 3 mg Cu/2000 kcal for the remainder of the study. Both groups received 3 mg Zn/2000 kcal for the first 90 d, followed by another 10 d equilibration period, and 53 mg Zn/2000 kcal for the next 90 d. High dietary zinc significantly (p<0.0001) increased extracellular superoxide dismutase (EC -SOD) activity among all of the subjects from 26.13 U/ml plasma at the end of the low dietary zinc period to 32.57 U/ml plasma at the end of the high dietary zinc period. There was no significant effect of dietary copper on EC-SOD activity. In contrast erythrocyte copper-zinc superoxide dismutase (CuZn SOD) activity was not significantly affected by dietary zinc. However, low dietary copper significantly depressed CuZn SOD activity by 17% and high dietary copper significantly increased glycosylated hemoglobin concentrations, plasma copper concentrations, and ionized magnesium concentrations. High dietary zinc significantly (p<0.05) increased plasma zinc concentrations and the percent platelet aggregation. These results suggest that 53 mg Zn/d has some adverse effects on copper metabolism. These results also suggest that measurement of EC-SOD activity may be a useful indicator of zinc status in humans.