Scientists from the University of Illinois have demonstrated that consuming soy products protect against colon cancer, in an animal model anyway.
Pregnant rats were fed soy protein isolate, genistein (a soy isoflavone) or a control diet. The rats born were fed the same diet and at 7 weeks exposed to a carcinogen and then continued on the diets for another 5 weeks. Rats fed genistein had a reduced number of pre cancerous lesions.
The scientists went on to show that genistein decreased the expression of three genes associated with abnormal growth. This adds weight to the hypothesis that colon cancer is an epigenetic disease, i.e. affected by diet and environmental factors.
The level of genistein and soy protein isolate used in this study were meant to be equivalent to the level that is consumed in Asian diets and the authors noted that colon cancer incidence has been shown to increase in Asians who adapt to a western diet.