Influence of meal distribution of wheat bran on fecal bulk, gastrointestinal transit time and colonic thymidine kinase activity in the rat.

Male Fischer 344 rats were fed either fiber-free (FF), continuous 10% wheat bran (CWB) or intermittent 50% wheat bran (IWB) diets for 6 wk to investigate possible alterations in physiological effects associated with colon cancer (fecal bulk, transit time, colonic cell proliferation) induced by meal distribution of the bran. The FF and CWB groups consumed unvaried diets throughout the day. The IWB group consumed two consecutive meals of a 50% bran diet for a total of 4 hr each day followed by a fiber-free diet for the remaining hours of the day. Similar daily quantities of bran were consumed in the CWB and IWB groups. Dry fecal weights rose significantly and transit times declined in both bran-fed groups independent of the meal distribution of bran. Colonic cell proliferation (estimated by thymidine kinase activity) was similar in all groups. The results suggest that these physiological effects of wheat bran are independent of the meal distribution of the bran.