Submitted to: Experimental Biology
Publication Type: Abstract Only
Publication Acceptance Date: 4/17/1999
Publication Date: N/A
Technical Abstract: Twenty-two postmenopausal women aged 50-76 y completed a metabolic unit study to investigate the effects of low and moderately high zinc intakes on Zn, Cu, and Fe status indicators. 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. Both groups received 3 mg Zn/2000 kcal for 90 d, followed by another 10 d equilibration period, and 53 mg Zn for the next 90 d. Zn indicators that were the most sensitive to changes in Zn status, based on increases in values when Zn supplements were fed, include plasma Zn (P<0.0001), extracellular superoxide dismutase (ESOD) (P<0.03), and erythrocyte membrane 5' nucleotidase (P<0.008). An interaction between Zn and Cu affected ESOD activity; the change in activity between low Zn and high Zn was greatest in the low Cu group. In addition, dietary Cu seemed to affect the activity when 3 mg Zn/d was fed, but not when 53 mg Zn/d was fed. Cu and Fe indicators that were significantly depressed when Zn supplements were fed included erythrocyte Cu,Zn superoxide dismutase (P<0.02), ceruloplasmin specific activity (enzyme activity/immunoreactive protein) (P<0.0008), and hemoglobin (P<0.0001). These data suggest that Zn intakes >50 mg/d are detrimental to Cu and Fe nutriture.