Author
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Lukaski, Henry |
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Johnson, Phyllis |
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Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 8/3/2005 Publication Date: N/A Citation: N/A Interpretive Summary: Copper functions as a component of specific proteins that serves in both energy production and protection against damage from oxygen use. These characteristics garner interest from the public seeking to increase physical activity and consume balanced diets to maintain health and prevent chronic diseases. Young men participated in a study and consumed diets containing the recommended amount (0.9 mg/d) and a higher amount (1.6 mg/d) of copper. Copper losses in feces, urine and sweat exceeded copper intake when they consumed the recommended compared to the higher amount of copper. When the men ate the recommended compared to the higher amount of copper, plasma and muscle copper concentrations decreased slightly and a specific copper-containing protein, ceruloplasmin, in blood decreased significantly. Cytochrome c oxidase activity in muscle decreased significantly after consumption of the recommended compared to the higher dietary copper. During low-level exercise, heart rate, ventilatory volume, total energy, anaerobic energy use, and blood lactate were significantly increased with the recommended compared to the higher copper intake. These findings indicate that dietary copper at an amount recommended to the public was associated with copper deficiency and impaired ability to use oxygen to produce energy needed to perform moderate physical activity. This information will be useful to dietetic professionals who counsel individuals seeking to begin physical activity programs to lose weight or increase physical fitness. It also will be informative to individuals who propose intakes of nutrients to promote health and well-being in the population. Technical Abstract: The role of copper in supporting integrated biological function during physical activity is not well understood. Although copper-containing proteins, such as cytochrome c oxidase, are known to enable oxygen utilization and, thus, facilitate energy production, there is an absence of information on the effect of copper intake on metabolic responses and energy metabolism during exercise. This study determined the effects of dietary copper at the recommended and a higher intake on indicators of copper status, cytochrome c oxidase activity in skeletal muscle and physiological responses during submaximal exercise. Eleven men, ages 27-38 y, were fed diets composed of Western foods in a controlled study with supplemental and recommended dietary copper [1.5 and 0.8 mg/10.5 MJ (2500 kcal/d)] diets. Functional responses to a standardized submaximal cycle ergometer test (50% peak intensity for 15 min) were determined at the end of each diet period. Dietary copper did not affect hemoglobin or hematocrit. Serum copper, ceruloplasmin activity and protein concentration, copper balance, muscle copper concentration and cytochrome c oxidase activity were lower (p<0.05) with the recommended compared to the higher dietary copper. Heart rate, oxygen uptake, ventilatory rate, total energy cost, anaerobic energy contribution, and plasma lactate were greater (p<0.05) during submaximal exercise after consumption of the recommended compared to the higher copper intake. These findings indicate that dietary copper in an amount recommended to the public results in copper deficiency and impaired metabolic responses during moderate physical activity in men. |
