Effect of bacterial metabolism in the intestine on colorectal tumors induced by 1,2-dimethylhydrazine in transgenic mice harboring human prototype c-Ha-ras genes

The number of colorectal tumors per mouse induced by 1,2-dimethylhydrazine in transgenic (Tg) mice carrying human c-Ha-ras genes was significantly red uced by ingestion of apple pectin (AP) or a culture condensate of Bifidobac terium longum(MB) compared with a control diet and non-Tg mice. However, th ere were no differences in the composition of fecal flora, water content, b eta -glucuronidase and beta -glucosidase activities, and concentrations of organic acids and putrefactive products in the feces between the AP or MB d iet and the control diet, or between the Tg mice and non-Tg mice. The conce ntration of secondary bile acids in the MB diet group was higher than that in the control group. These results suggested that there was no relationshi p between prevention of colorectal tumors in Tg mice and the AP or MB diet, or improvement of the intestinal environment due to these functional foods .