Modification of stool content by increased bran intake.

Six healthy subjects, four males and two females, were studied for 8 weeks with daily dietary history, 72-hr weekly stool collections, and analysis of stool specimens for fecal weight, water, pH, and total aerobic and anaerobic qualitative and quantitative bacteria. Subjects were studied first for a 3-week control period, followed by 3 weeks of 5.4 g of crude fiber supplementation daily (Kellogg's "All Bran"), and then by a 2-week control period. Analysis of diets revealed that the mean intake of crude fiber rose to at least 10 g/day, and stool volume increased significantly during the high-fiber intake. The stools remained at the same pH, and the same percentages of water and solids were present durin- control and high-fiber-intake periods. Bacteriological analysis revealed no significant differences in qualitative or quantitative counts; however, the ratio of anaerobic to aerobic organisms appeared to increase.