A VERY-LOW INTAKE OF FAT IS REQUIRED TO DECREASE FECAL BILE-ACID CONCENTRATIONS IN RATS

The purpose of this study was to determine the effect of different amounts of dietary fat on colonic cell proliferation and fecal bile acid concentrations. Thirty-nine male Sprague-Dawley rats were randomly assigned to three diets (13 rats per diet) containing 5, 10 and 20 g butter/100 g diet. Diets were fed for 3 wk. As fat intake increased, total fecal fat excretion remained constant. When dietary fat was decreased from 20 to 10 g/100 g diet, total fecal bile acid concentrations tended to increase 14.5%. However, a further reduction to 5 g butter/100 g diet significantly decreased fecal total bile acid concentration by 48% from the concentration in feces of rats fed 10 g butter/ 100 g diet. The concentration of deoxycholate (considered a highly promotive bile acid) was not reduced unless the amount of fat in the diet was reduced to 5 g/ 100 g. Labeling index was used as an intermediate marker for colon carcinogenesis. For deoxycholate, a decrease of fat intake to 5 g/100 g diet decreased the cecal labeling index relative to those of rats fed 10 or 20 g butter/100 g diet. These data indicate that decreasing the dietary fat from 20 to 10 g/100 g does not decrease fecal bile acid concentration or colonic cell proliferation, but some effects are seen in rats fed 5 g butter/100 g diet.