Effects of three proteins on absorption of cadmium in rats.

The effects of 3 proteins on the gastrointestinal absorption of cadmium were studied. Glycinin and ovalbumin significantly decreased cadmium in liver and the total cadmium in the tissues of rats following a single oral administration of cadmium. In addition, in rats fed continuously with the experimental diets containing cadmium together with proteins, glycinin and ovalbumin significantly decreased the contents of cadmium in the tissues. These results show that the proteins depressed the gastrointestinal absorption of cadmium. Moreover, the effects of cadmium on various digestive enzymes for proteins and the pepsin or pepsin-pancreatin digestion of the proteins were examined. As a result it is likely that the inhibitory effect of cadmium on the intestinal digestion of these proteins is one of the causes of the inhibitory effects of the proteins on the intestinal absorption of cadmium in rats. The undigested oligopeptides may decrease the amount of free cadmium available to be absorbed from the intestine by binding cadmium itself, resulting in decreased intestinal absorption of cadmium.