EFFECTS OF DIETARY PROTEIN, CALCIUM, PHOSPHORUS AND FIBER ON RENAL ACCUMULATION OF EXOGENOUS CADMIUM IN YOUNG RATS

Abstract

The present study focused mainly on the relative ability of each of dietary components; protein, minerals (calcium and phosphorus) and dietary fiber, to prevent the renal damage due to chronic oral alimen-tation of Cd in young female rats. Renal accumulation of Cd was assessed over an experimental period of one month, which reflects mainly on Cd input from the gut.
In comparison with rats fed a multi-nutritionally deficient, Cd-added diet, Cd concentration in the kidney was markedly reduced by supplementation with Ca and P (p<0.001), significantly decreased by high protein (p<0.05), and by dietary fiber (p<0.05), and by combined supplementation with protein and fiber (p<0.02), respectively. Supplementation with these three components brought about a remarkable reduction in a similar level to that in rats fed a normal balanced, Cd-added diet.
These individual dietary factors, however, are considered to play a distinctly different role in preventing renal Cd accumulation: supple-mentation with protein behaves rather non-specifically through im-provement of general condition (i.e., growth, food intake, food efficiency, fecal output), and addition of fiber is mostly responsible for marked shortening of gastrointestinal transit time and enhanced fecal output. In contrast, supplementation with minerals is the most effective in reduced input of Cd, presumably due to a specific interaction of divalent ions; Ca-Cd on the mucosal phase of Cd transport.