EFFECTS OF DIETARY FIBER ON GASTROINTESTINAL TRANSIT-TIME, FECAL PROPERTIES AND FAT-ABSORPTION IN RATS

The gastrointestinal transit time of food was determined by x-ray fluo roscopy using barium sulfate in rats fed with diets of various dietary fiber contents, and the effects of dietary fiber on the transit time, properties of feces, and fat absorption mere examined. In 4- and 16-m onth-old rats fed with the diet for 3 and 15 month, respectively, the transit time of the cecum and colon in those receiving 20 and 40% whea t bran diets was shortened compared with that in the 0% group. The fec al pellet number and volume increased as the wheat bran content of the diet increased. In another experiments, the daily total fat excretion was found to be the greatest in rats receiving 15% pectin diet, follo wed by rats receiving 15% cellulose and non-fiber diets, respectively. These results suggest that shortening of the transit time through the cecum and colon with increase of fecal volume and suppression of fat absorption all participate in the mechanism of the inhibitory action o f wheat bran on carcinogenesis and on the development of diverticulum of the large intestine.