THE EFFECT OF SOY ISOFLAVONES ON THE DEVELOPMENT OF INTESTINAL NEOPLASIA IN APC(MIN) MOUSE

Data from epidemiological studies suggest that isoflavones in soy may have a protective effect on the development of colon cancer in humans. Therefore, we have investigated whether soy isoflavones will inhibit intestinal tumour development in Apc(Min) mice. The mice were fed a We stern-type high risk diet (high fat, low fibre and calcium) containing two different isolates of soy protein as a protein source. For the co ntrol and test groups this resulted in the administration of about 16 and 475 mg of total isoflavones per kg diet, respectively. As a positi ve control, a third group of mice was administered a low isoflavone di et supplemented with 300 ppm sulindac. No significant differences in t he incidence, multiplicity, size and distribution of intestinal tumour s were observed between Min mice fed low and high isoflavone-containin g diets. However, a clear reduction in the number of small intestinal tumours was observed for the sulindac diet. Thus, in contrast to epide miological studies, our results demonstrate that high amounts of soy i soflavones present in a Western-type high risk diet do not protect aga inst intestinal tumour development in a relevant animal model such as the Min mice. (C) 1998 Elsevier Science Ireland Ltd. All rights reserv ed.