EFFECTS OF A DIET LOW IN COPPER ON COPPER-STATUS INDICATORS IN POSTMENOPAUSAL WOMEN

To study the effects of low copper intake in older individuals, 12 pos tmenopausal women, aged 63.1 +/- 8.8 y, were fed a diet containing 9 m u mol (0.57 mg) Cu/d for 105 d, followed by a copper-repletion period of 35 d during which the diet was supplemented with 31.5 mu mol (2.0 m g) Cu/d. Plasma copper and ceruloplasmin did not change significantly during copper depletion but ceruloplasmin decreased during copper repl etion. Erythrocyte superoxide dismutase activity dropped significantly during low copper intake from 3450 to 2600 U/g hemoglobin, but did no t increase during copper repletion. Platelet cytochrome c oxidase acti vity changed significantly (P < 0.0001) from 1740 to 810 U/g protein d uring copper depletion, then increased to 1000 U/g protein during copp er repletion. Erythrocyte glutathione peroxidase activity responded si milarly. Clotting factor VIII activity increased significantly during copper depletion, then dropped during copper repletion. Low copper int akes did not induce the changes in serum cholesterol and hematology ge nerally found in copper-deficient animal models. These results indicat e that a paradigm shift may be needed in evaluating copper status in a dult humans. Sensitive indicators of copper include functional activit ies of platelet cytochrome c oxidase, platelet copper, glutathione per oxidase, and clotting factor Vm. Plasma copper, ceruloplasmin, and cho lesterol are relatively insensitive indicators. Also, the recovery fro m mild copper depletion may require more aggressive intervention than 2 mg Cu/d for 35 d.