Submitted to: American Journal of Clinical Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/2/1995
Publication Date: N/A
Interpretive Summary: Adult human requirements for copper are a controversial issue. This is the result of apparent inconsistencies in findings from reported studies on copper deprivation and the lack of a generally agreed upon index of copper nutritional status in adult humans. In a study of postmenopausal women fed a diet low in copper (0.57 mg of copper per day) for 105 days, signs normally found in copper-deficient animals such as changes in plasma copper, cholesterol, and hemoglobin were not observed. Variables associated with oxygen metabolism and antioxidant status, such as the functional activities of copper-containing enzymes superoxide dismutase and cytochrome c oxidase in blood cells, various blood clotting factors, and glutathione peroxidase in red blood cells are relatively sensitive indicators of changes in copper. Also, recovery from copper deficiency may require more aggressive intervention than the 2 mg of copper per day that was previously believed to be needed. These results indicate that a change in thinking may be needed in evaluating copper deprivation in adult humans.
Technical Abstract: To study the effect of copper deprivation in older individuals, 12 postmenopausal women, aged 63.1 /- 8.8 y, were fed a diet containing 0.57 mg copper per day for 105 days, followed by a copper repletion period of 35 days where the diet was supplemented with 2.0 mg of copper per day. Plasma copper and ceruloplasmin did not change significantly during copper deprivation but decreased during copper repletion. Erythrocyte superoxide dismutase activity dropped significantly during copper deprivation from 3450 to 2600 U per mg hemoglobin, but did not increase during copper repletion. Platelet cytochrome c oxidase activity significantly (P<0.0001) fell from 1.74 to 0.81 U per mg protein during copper depletion, then increased to 1.00 U/mg protein during copper repletion. Erythrocyte glutathione peroxidase activity responded similarly. Clotting factor VIII activity increased significantly during copper deprivation, then dropped during copper repletion. Copper deprivation did not induce changes in serum cholesterol and hematology normally found in copper deficient animal models. These results indicate that a paradigm shift may be needed in evaluating copper deprivation in adult humans. Sensitive indicators of copper include functional activities of platelet cytochrome c oxidase, glutathione peroxidase, and clotting factor VIII. Plasma copper, ceruloplasmin, and cholesterol are relatively insensitive indicators. Also, the recovery from copper depletion may require more aggressive intervention than 2 mg of copper per day for 35 days.