Soy isoflavones in food, rather than pure form, better for ER-dependent disease.

2004 NOV 4 - (NewsRx.com & NewsRx.net) -- Soy isoflavones in food, i.e., soy flour-containing foods, rather than isoflavones in pure form are better for women with estrogen-dependent breast cancer, recommend nutritionists at the University of Illinois.

"Soy-based products consumed in Asian countries are minimally processed whereas in the USA many of the soy foods and soy ingredients are highly processed. Soy foods contain complex mixtures of bioactive compounds, which may interact with one another," wrote C.D. Allred and colleagues.

They studied "the ability of various soy products containing genistin, the glycoside form of genistein, to affect growth of MCF-7 cells transplanted into ovariectomized athymic mice. Products investigated included soy flour, two crude extracts of soy (soy molasses and Novasoy), a mixture of isoflavones, and genistin in pure form."

"Each of the soy flour-processed products was added to the diet to provide equivalent amounts of genistein aglycone equivalents (750 ppm)," the researchers said.

They reported that "tumors in the negative control animals regressed throughout the study while the tumors in the soy flour-fed animals remained basically the same size (neither grew nor regressed) ."

"In animals consuming soy molasses, Novasoy, mixed isoflavones, or genistin alone, tumor growth was stimulated when compared with animals consuming a control diet devoid of soy. These same dietary treatments resulted in increased cellular proliferation," Allred and coworkers said.

They also studied "changes in mRNA expression of gene targets (estrogen responsiveness, cell ...