May Help Prevent Breast Cancer Release No. These findings underscore the importance of research as the critical link between nutrition and health. In laboratory studies, researchers compared the protective effects of soy protein and whey protein against chemically induced tumors in the milk producing glands of rats. They found that approximately 50 percent fewer rats had mammary tumors when fed a diet containing a processed whey protein as compared with rats eating a standard diet.
Whey protein is a class of minor proteins found in milk.
Soy protein prevented approximately 25 percent of mammary cancer. Among the rats that ate the whey diet, those that developed mammary cancer had fewer and smaller tumors than control rats.