Supplementing Copper at the Upper Level of the Adult Dietary Recommended Intake Induces Detectable but Transient Changes in Healthy Adults

Abstract

The health consequences of mild copper excess in humans are unknown. In a previous study, 2 moof supplementation with up to 6 mg Cu/L in drinking water did not induce detectable changes. Here we assesseda copper supplement at the upper level of dietary recommendations for “healthy” adults. The study was aprospective controlled trial; participants (women and men, 18–50 y old), represented the upper and lower 5% ofthe ceruloplasmin distribution curve obtained from a community-based sample of 800 healthy adults (n 41/group, each 50% men). Individuals received a single daily dose of 10 mg Cu for 60 d. Before and aftersupplementation, blood [copper, ceruloplasmin protein, homocysteine, liver aminotranferases, Cu-Zn -superoxidedismutase activity in erythrocytes (eSOD), and glutathione in peripheral mononuclear cells] and urine [copperexcretion after a 5-h administration of a chelator 2,3-dimercapto-1-propano-sodium sulfonate (DMPS)] analyseswere performed. After 2 mo, liver enzyme activities remained below the clinical cutoff value used to diagnose liverdysfunction, but had increased significantly in both groups and genders. These increases were no longer present12 mo after the copper loading period was completed. Glutathione in mononuclear cells (mmol/g of protein) alsoincreased after the 2-mo copper loading in both groups and in both genders (P 0.01). eSOD activity, serumhomocysteine concentration, and urinary copper excretion 5 h after DMPS administration were not affected. Weconclude that copper administered as described induced a transient, mild, but significant elevation of aminotransferases