Diets high in fat and low in dietary fiber have been associated with a higher incidence of colon cancer, possibly by increasing bile acid concentration in the colon. Therefore changes in bile acid metabolism due to beef tallow, corn bran (CB), and soy polysaccharide (SP) feeding were studied. Rats were fed one of four diets for six weeks: 5% beef tallow fiber-free (LF), 20% beef tallow fiber-free (HF), 20% beef tallow with CB (HFCB), and 20% beef tallow with SP (HFSP). HF increased fecal output compared with LF, and HFCB and HFSP increased fecal output compared with HF. HF reduced fecal bile acid concentration by two-thirds compared with LF, although daily bile acid excretion was similar. There was a tendency toward a smaller bile acid quantity in the small intestine with HF than with LF. Neither fiber altered total fecal bile acid concentration or small intestinal bile acid quantity compared with HF. However, 7α-dehydroxy-lase activity in the colon was lower with HFSP than with HFCB. Increasing dietary beef tallow from 5% to 20% in animals fed a fiber-free diet greatly reduced the concentration of bile acids in the large intestine and feces, an effect associated with a reduced risk of colon cancer.
Bibliographical noteFunding Information:
This investigation was supported by Public Health Service Grant CA-40843 awarded by the National Cancer Institute, Department of Health and Human Services. This is Paper 19-255 of the scientific series of the Minnesota Agricultural Experiment Station on research conducted under the Minnesota Experiment Station Project 18-058. This study was presented in part at the 73nd Annual Meeting of the Federation of American Societies of Experimental Biology, New Orleans, LA, March 1989 and published in abstract form (Gallaher, D, and Chen, C-L: "Effect of High Beef Fat, Corn Bran, and Soy Polysaccharide on Bile Acid Metabolism in the Rat." FASEB J 3, A470, 1989). This work was conducted at the Department of Food and Nutrition, North Dakota State University (Fargo, ND). Address reprint requests to Dr.Daniel D.Gallaher,Dept.of Food Science and Nutrition, 1334 Eckles Ave., University of Minnesota, St. Paul, MN 55108.