ARS | Publication request: Marginal Intakes of Zinc, Iron, and Calcium Enhance the Accumulation of Cadmium in the Intestine of Rats Fed a Rice-Based Diet

Submitted to: Journal of Federation of American Societies for Experimental Biology
Publication Type: Abstract
Publication Acceptance Date: December 2, 2002
Publication Date: March 14, 2003
Publisher's URL: http://www.fasebj.org
Citation: Reeves, P.G., Chaney, R.L. 2003. Marginal intakes of zinc, iron, and calcium enhance the accumulation of cadmium in the intestine of rats fed a rice-based diet [abstracat]. The Federation of American Societies of Experimental Biology Journal 17:A1163.

Technical Abstract: The essential dietary minerals Zn, Fe, and Ca are antagonistic to Cd absorption. We showed earlier that rats fed a rice-based diet with marginal nutrient content of these nutrients absorbed much more Cd than rats consuming an adequate supply of these minerals (Environ. Sci. & Technol., 36: 2684-2692, 2002). The present experiment was designed to determine the effects of marginal dietary Zn, Fe, and Ca on the uptake and turn-over rate of Cd along the GI tract. Two groups of weanling female rats (6/trt) were fed a diet containing 40% cooked, dried rice containing 0.6 ppm Cd. The diet of one group contained adequate Zn (35 ppm), Fe (30 ppm), and Ca (5,000 ppm), while the other group contained marginal Zn (6 ppm), Fe (9 ppm), and Ca (2,500 ppm). Rats were fed the diets for 5 weeks and then orally dosed with 1 g of diet containing 0.4 g of 109**Cd-labeled rice. At times ranging from 0.25 to 64 d after dosing, rats were killed and the intestine removed to determine 109**Cd and total Cd accumulation. Shortly after dosing, the % dose of 109**Cd was 6 times higher in the duodenum of marginal rats than controls. After 64 d, it was 10 times higher than controls; however, of the duodenal isotope at d-1, only 0.2% remained by d-64. After 5 wks, Cd concentration in the duodenum of the marginally fed rats was 7 times higher than in adequately fed rats. Cd concentration in liver and kidney was 5 times higher in the marginally fed rats. These data suggest that marginal intakes of Zn, Fe, and Ca cause hyper-accumulation of Cd in the duodenum. This in turn, results in a greater rate of Cd absorption, and greater accumulation in the internal organs.