Copper intake and assessment of copper status.

The diagnosis of marginal copper deficiency has not been perfected despite an increased understanding of the physiologic roles of copper. The use of nonstandardized procedures and the effects of factors other than copper nutriture have impeded identification of an ideal indicator of copper nutritional status in humans. A review of studies of experimental copper deprivation conducted in adult humans over the past 12 y indicated that between 1.0 and 1.25 mg Cu/d is needed by adults for copper maintenance for periods of up to 6 mo and that < or = 2.6 mg Cu/d for periods of up to 42 d is not sufficient for recovery from copper deprivation. Copper-containing enzymes in blood cells, such as erythrocyte superoxide dismutase and platelet cytochrome-c oxidase, may be better indicators of metabolically active copper and copper stores than plasma concentrations of copper or ceruloplasmin because the enzyme activities are sensitive to changes in copper stores and are not as sensitive to factors not related to copper nutriture.