EFFECT OF WHEAT BRAN FIBER ON THE DEVELOPMENT OF MAMMARY-TUMORS IN FEMALE INTACT AND OVARIECTOMIZED RATS TREATED WITH 7,12-DIMETHYLBENZ(A)ANTHRACENE AND IN MICE WITH SPONTANEOUSLY DEVELOPING MAMMARY-TUMORS

We examined the effect of consumption of graded increases of dietary f iber (soft white wheat bran) on the development of mammary gland carci nomas in intact female Sprague-Dawley rats during the promotion stage of carcinogenesis, induced with 7,12-dimethylbenz(a)anthracene (DMBA), The percent of rats with mammary carcinomas, the total number of mamm ary carcinomas and the mean number of mammary carcinomas per rat were reduced significantly at all fiber levels examined compared to rats fe d a control diet, Inclusion of 9.6% fiber in the diets of ovariectomiz ed rats that had been treated with a single i.v. dose of 2.5 mg DMBA/1 00 g body weight 2 weeks prior to removal of the ovaries resulted in a significant decrease of carcinomatous and benign mammary tumors compa red to ovariectomized rats fed a control diet, Development of spontane ous mammary carcinomas in virgin C3H/HeOuJ female mice and growth of a transplantable mammary gland tumor in such mice were reduced by inclu sion of 9.6% fiber in the diet, a reduction that was significant or ju st barely missed significance, depending on the source of the fiber, O ur observations provide evidence that inclusion of soft white wheat br an in the diet is effective in the suppression of mammary gland tumori genesis in an array of experimental animal models. (C) 1998 Wiley-Liss , Inc.