Submitted to: Journal of Federation of American Societies for Experimental Biology
Publication Type: Abstract Only
Publication Acceptance Date: November 10, 2005
Publication Date: March 6, 2006
Citation: Saari, J.T., Reeves, P.G. 2006. Pinto beans are a good source of dietary copper [abstract]. Journal of Federation of American Societies for Experimental Biology. 20(4):A554. Technical Abstract: The trace element copper (Cu) is a required nutrient in the diets of humans. It has been shown in animal studies to be essential for efficient absorption of iron, efficient oxygen utilization, and for aiding in free-radical degradation. Dry beans are potentially good sources of Cu; thus, the objective of this study was to determine the bioavailability of Cu from dry beans by using the pinto bean as the source. Dry beans were obtained from a local market, cooked according to package directions, and dried. Weanling male rats (6 groups of 8 rats each) were fed a Cu-deficient diet (AIN-93G) for four weeks followed by two weeks of Cu repletion with diets containing 0 to 6.5 mg Cu/kg diet added as CuSO4, or with 0.6 and 1.5 mg Cu/kg incorporated into rat diets as pinto beans at 10% and 20%. Then, standard response curves were developed based on the changes in Cu-dependent enzyme activities and organ Cu concentrations in response to increasing dietary Cu as CuSO4. The changes in these parameters in rats fed the pinto bean diets were compared to the values on the standard response curve at similar levels of dietary Cu. Based on the regeneration of ceruloplasmin activity, a sensitive Cu-dependent serum ferroxidase, and kidney Cu concentration, the bioavailability of Cu from dry beans was 100% of that in the highly available CuSO4. Based on the regeneration of extra-cellular superoxide dismutase, another Cu-dependent enzyme, the bioavailability of bean Cu was about 20% higher than that from CuSO4. We conclude that the dry pinto bean is an excellent economical source of dietary Cu that is highly bioavailable.