Soy Protein May Effect Colon Cancer

Aug 22, 2004 01:38 PM EDT

Recent research has found that estrogen may protect against colon cancer, and may help minimize the number and size of tumors that do occur.

Five diets tested

In the study, published in the Journal of Nutrition, researchers fed female mice five different diets and followed their progress for a year. The five diets were designed to compare the effects of specific ingredients on the test subjects.

Diet one was made with milk protein, and diet two contained soy protein. Both diets were lacking any form of estrogen. The other three diets contained soy protein and an estrogen component.

Diet three contained soy protein and genistein, an estrogen-like compound found in soy. Diet four contained Novasoy, a commercial product containing a mixture of soy-derived compounds including genistein. Diet five contained estrone, a naturally occurring human estrogen.

Reduced tumor size

The scientists found that while all the soy/estrogen diets gave some protection, the diet containing estrone was the most effective in preventing colon cancer. This is the first time such a finding has been documented.

The dose of estrone the mice received was similar to levels used in hormone replacement therapy. The researchers also discovered that those mice that ate soy protein and did develop colon cancer had fewer and smaller tumors than those mice that did not eat soy protein.


1. R. S. MacDonald; “Dietary Soy Isoflavones and Estrone Protect Ovariectomized ERKO and Wild-Type Mice from Carcinogen-Induced Colon Cancer,” Journal of Nutrition, 2004: 134: 179-182