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USDA-Funded Research Finds That Soy, Whey Proteins May Help Prevent Breast Cancer

By Tara Weaver-Missick
January 20, 2000

Click here to view the scientific abstract in Cancer, Epidemiology, Biomarkers and Prevention.

WASHINGTON, Jan. 20--Researchers at the Arkansas Children's Nutrition Center have found that whey and soy protein may help prevent breast cancer. This research, funded by the U.S. Department of Agriculture, is featured in this month’s Cancer, Epidemiology, Biomarkers and Prevention, an official journal of the American Association for Cancer Research.

“This significant new research, although preliminary, suggests that adding whey or soy protein to the diet may help protect women and children from developing breast cancer,” said Agriculture Secretary Dan Glickman. “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. According to ACNC Director Thomas Badger, who heads the USDA-funded project, 180,000 new breast cancer cases are diagnosed each year in women living in the United States.

Rats were fed one of three diets, each with a different protein: a control diet containing the major milk protein casein, a diet made with soy protein isolate, or a diet with processed whey protein.

All rats in the control group developed at least one tumor; 77 percent of the soy-fed rats had at least one tumor; and about 54 percent of the whey- fed rats had at least one tumor. Among the rats that ate the whey diet, those that developed mammary cancer had fewer and smaller tumors than control rats.

“These data indicate that feeding rats diets made with whey protein can prevent mammary tumor formation in the major animal model of human breast cancer and illustrate the importance of dietary factors in disease prevention,” said Badger, who has filed for a patent on the whey compound.

Scientific contact: Thomas Badger, Arkansas Children's Nutrition Center, Little Rock, Ark., phone (501) 320-2785, fax (501) 320-2818,