G L Schoeffler | PubMed Health

PubMed1994

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.

Animals↗

PubMed1994

Rats fed high fat diets with increased calcium levels have fecal bile acid concentrations similar to those of rats fed a low fat diet.

The mechanism by which calcium may protect against colon carcinogenesis was studied in rats fed three levels of calcium (0.5, 1.0 and 1.5 g/100 g diet) and a high butter diet (20 g/100 g). Results were compared with values obtained using a low butter diet (5 g/100 g) supplemented with 0.5 g Ca/100 g diet. Concentration and relative proportions of individual fecal bile acids were determined by gas chromatography, and in vivo colonic cell proliferation was assessed using [3H]thymidine. Total fecal output and total fecal lipids increased as dietary calcium increased. When calcium supplementation remained at 0.5%, raising the level of fat in the diet increased the fecal concentrations of deoxycholate, omega-muricholate and total bile acids. However, when the level of fat supplementation remained constant at 20 g/100 g diet, but dietary calcium was 1.0 or 1.5 g/100 g, the concentration of these bile acids returned to the level found in feces of rats fed the low fat diet. Despite the significant decrease in the concentrations of certain fecal bile acids with increasing calcium supplementation, these differences were not reflected in substantive changes in epithelial cytokinetics. These data show that in rats fed high butter diets, 1.0% calcium is sufficient to lower total bile acid concentration and the concentrations of certain individual bile acids to those found in feces of rats fed low fat diets. Despite the significant effects of calcium on bile acid concentrations, minimal effects were observed on indices of colonic cell proliferation.

Animals↗