Soy protein isolate consumption protects against azoxymethane-induced colon tumors in male rats

Male Sprague-Dawley rats (F-2 generation) that had been fed modified Americ an Institute of Nutrition-93G diets formulated with a single protein source of either casein or soy protein isolate for their entire life received azo xymethane once a week for 2 weeks (s.c., 15 mg/kg) starting at age 90 days, Forty weeks later, all rats were euthanized. the colon was examined visual ly for masses and these were subsequently evaluated histologically, Rats fe d the casein diet had a 50% incidence of colon tumors compared with 12% on soy protein-based diets (P < 0.05), These results suggest that consumption of soy protein-containing diets may reduce the risk of developing colon tum ors. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.