The effect of copper supplementation on red blood cell oxidizability and plasma antioxidants in middle-aged healthy volunteers

A multicenter European study (FoodCue) was undertaken to provide data on th e significance of increased dietary copper as a pro-oxidant or antioxidant in vivo. The present work describes the effect of Cu supplementation on (2, 2' -azo-bis(2-amidinopropane) hydrochloride (AAPH)-induced red blood cell o xidation in middle-aged people. Double-blinded copper supplementation was a chieved in 26 healthy volunteers (50-70 years) with pills containing 3 mg C uSO4, 3 mg Cu glycine chelate (CuG) and 6 mg Cue. Each 6 week supplementati on period was preceded and followed by 6 weeks of washout (WO) on placebo. The results show significant increases in time necessary to achieve 50% hem olysis (LT50) after 3CuSO(4) and 6CuG compared with values after WO periods . Cu supplementation did not increase the levels of (Cu,Zn)SOD activity in red blood cells. Resistance to hemolysis was significantly and positively c orrelated (r = .30, p < .01) with alpha- and beta-carotene content in the p lasma. Together,these data suggest that intake of copper as high as 7 mg/d has no pro-oxidant activity and may rather result in protection of red bloo d cells against oxidation. The decreased oxidizability of red blood cells d id not result from increased (Cu,Zn)SOD activity and may occur through othe r mechanisms such as changes in membrane antioxidant content. (C) 2000 Else vier Science Inc.