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United States Department of Agriculture

Agricultural Research Service

Title: Effect of Long-Term, High-Copper Intake on Concentration of Plasma Homocysteine and B Vitamins in Young Men

Authors
item Tamura, Tsunenobu - UNIV. ALABAMA, NUTR. SCI.
item Turnlund, Judith

Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 11, 2004
Publication Date: October 1, 2004
Citation: Tamura, T., Turnlund, J.R. Effect of long-term, high-copper intake on concentration of plasma homocysteine and b vitamins in young men. Journal of Nutrition. 2004. 10:757-759.

Interpretive Summary: Studies on the interaction between copper nutriture and the metabolism of folate and homocysteine are limited and no data are available on the effect of copper supplementation on their metabolism. Therefore we investigated the effects of a long-term (147 days), high-copper intake (7.8 mg/day) on plasma homocysteine, folate, vitamin B-12, and pyridoxal-5'-phosphate concentrations in healthy young men. Long-term high-copper intake resulted in small, but significant decreases in plasma homocysteine and folate concentrations. There was no effect of the high copper intake on plasma vitamin B-12 and pyridoxal - 5'-phosphate concentrations. These findings are consistent with our previous findings in rats suggesting that methionine synthase is copper dependent, and homocysteine and folate metabolism are regulated in part by copper nutriture. It may be necessary to consider copper nutriture for the interpretation of plasma tHcy concentrations in humans.

Technical Abstract: OBJECTIVES: We evaluated the effect of a long-term, high-copper intake on plasma total homocysteine (tHcy), folate, vitamin B-12 and pyridoxal-5'-phosphate (PLP) concentrations in humans. METHODS: Nine young healthy men were confined in a metabolic research unit (MRU) for 18 days and fed three-day rotation diets supplying an average of 1.6 mg copper/day followed by 129 days of free-living conditions when they received 7mg copper/day in addition to their usual diets. The subjects returned to the MRU for the second 18-day period and were given diets same as the first 18-days with the exception that the copper intake was 7.8 mg/day. There was no apparent biochemical indication that the subjects were copper deficient before the high-dose copper intake. Blood samples were obtained at the end of the first and second 18-day periods at the MRU, and plasma homocysteine (tHcy), folate, vitamin B-12 and pyridoxal phosphate (PLP) concentrations were measured. RESULTS: The long-term high-copper intake resulted in small, but significant decreases in plasma tHcy and folate concentrations. There was no effect of the high copper intake on plasma vitamin B-12 and PLP concentrations. CONCLUSION: These findings are consistent with our previous findings in rats suggesting that methionine synthase is copper dependent, and homocysteine and folate metabolism are regulated in part by copper nutriture. It may be necessary to consider copper nutriture for the interpretation of plasma tHcy concentrations in humans.

Last Modified: 10/25/2014
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