Dietary fiber: the effect of particle size of wheat bran on colonic function in young adult men

• Published in: The American journal of clinical nutrition Vol. 33; no. 8; pp. 1734 - 1744
• Main Authors: Heller, S N, Hackler, L R, Rivers, J M, Van Soest, P J, Roe, D A, Lewis, B A, Robertson, J
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.08.1980
• Subjects: Adult; Cellulose - metabolism; Colon - physiology; Dietary Fiber - metabolism; Feces - analysis; Humans; Intestines - physiology; Male; Particle Size; Triticum
• ISSN: 0002-9165; 1938-3207
• DOI: 10.1093/ajcn/33.8.1734

The effect of particle size of dietary wheat bran on human colonic function was studied in young adult men. Controlled, low-fiber diets supplemented with 32 g of either coarse or finely ground bran were served daily in a metabolic unit. Measurements of the mean transit time were made using polyethylene glycol and barium impregnated radioopaque pellets. In subjects receiving equal levels of both bran diets, coarse bran produced significantly (P = 0.95) shorter mean transit time than did finely ground bran. Values of mean transit time for coarse bran were 42.3 hr (polyethylene glycol) and 37.4 hr (pellets) while 57.9 hr (polyethylene glycol) and 56.5 hr (pellets) were found for fine bran. Daily fecal wet and dry weights from the coarse bran diet were found to be significantly greater by 14% (P = 0.99) and 7% (P = 0.95) than the weights found during the ingestion of finely ground bran. The moisture content of feces from subjects receiving the coarse bran diet was 75.2%, significantly higher (P = 0.99) than the value of 72.3% found with fine bran. No significant differences in the number of defecations per day were noted. Mean digestibilities for hemicellulose was 50% for coarse bran and 54% for fine bran. Cellulose digestibility was 6% in the coarse bran diet and 23% in the fme bran. While significant differences (P = 0.95) in digestibilities between the two brans were not shown, mean digestibilities were greater for fine bran components. Results from this study indicate that finely ground wheat bran is less effective than coarse bran in holding water in the feces and in promoting rapid transit of digesta through the gut. These findings suggest that coarse bran and food products fortified with coarsely ground bran should be the choice of patients with diverticular disease and of people desiring a high fiber diet to promote colonic health.