Influence of dietary fiber on transit time, fecal composition, and myoelectrical activity of the primate right colon.

The effect of varying dietary fiber intake on colon motor and electrical spike activity, transit time, and fecal content were studied in stump-tailed monkeys. Mean dry fecal weight increased with increasing fiber intake, but percentage water content did not change. Mean transit time was delayed when the diet contained less than 10 g dietary fiber daily. The clearance of polyethylene glycol and chromium sesquioxide also was slower on a low-fiber intake. Electrical spike discharge activity was greatest in the cecum and increased with increasing fiber intake. The effect of fiber on electrical spike activity progressively decreased distally along the colon. The contraction frequency of circular muscle, recorded with implanted strain gages, was greater in the cecum on a low-fiber diet, but this effect was less marked in transverse colon, and no significant differences were seen more distally.