INTERACTION OF DIETARY CA, P, MG, MN, CU, FE, ZN AND SE WITH THE ACCUMULATION AND ORAL TOXICITY OF CADMIUM IN RATS

The toxicity of Cd was examined in rats fed diets containing 30 mg Cd/kg as CdCl2 for 8 wk. The Cd-containing diets were supplemented with various combinations of the minerals Ca, P, Mg, Mn, Cu, Fe, Zn and Se in order to investigate the protective effect of these mineral combinations on Cd accumulation and toxicity. The mineral combinations were chosen such that the effect of the individual components could be analysed. At the end of the 8-wk feeding period, the Cd concentrations in the liver and renal cortex were 13.9 and 19.5 mg/kg body weight, respectively. The feeding of 30 mg Cd/kg diet alone resulted in well known Cd effects, such as growth retardation, slight anaemia, increased plasma transaminase activities and alteration of Fe accumulation. Only supplements that contained extra Fe resulted in a significant protection against Cd accumulation and toxicity. The most pronounced effect was obtained using a supplement of Ca/P, Fe and Zn, which resulted in a 70-80% reduction in Cd accumulation in the liver and kidneys, as well as a reduction in Cd toxicity. The protective effect of the mineral combinations was mainly due to the presence of Fe2+, but in combinations with Ca/P and Zn the effect of Fe was most pronounced. Compared with Fe2+ the protective effect of Fe3+ was significantly lower. Addition of ascorbic acid to Fe in both forms improved the Fe uptake, but consequently did not decrease Cd accumulation. Thus, the mineral status of the diet may have a considerable impact on the accumulation and toxicity of Cd, fed as CdCl2 in laboratory animals. For the risk assessment of Cd intake, special consideration should be given to an adequate intake of Fe.