AJP - Gastrointestinal and Liver Physiology, Vol 255, Issue 5 633-G639, Copyright © 1988 by American Physiological Society
Radiographic analysis of the effect of dietary fibers on rat colonic transit time
J. R. Lupton and M. M. Meacher
Department of Animal Science/Nutrition, Texas A&M University, College Station 77843.
The effect of different fiber sources on colonic transit time was charted
using serial radiographs. Sixty male Sprague-Dawley rats, 10 rats per
group, were provided with either a fiber-free control diet or the control
diet uniformly diluted to provide 8% dietary fiber from guar, pectin,
cellulose, wheat bran, or oat bran. At surgery, radiopaque markers were
inserted at defined distances in the mesentary closest to the large bowel.
Three weeks postsurgery, the animals were intubated with 0.5 ml of a
radiopaque marker, and radiographs were taken at 15-min intervals. Of the
two poorly fermented fibers, cellulose was as slow as and wheat bran was
faster than the fiber-free controls at five out of the six bowel segments
measured. The fermentable fibers (pectin, guar, and oat bran) were fast
through some bowel segments and slow through others. This study provides in
vivo data on colonic transit time and shows that neither 24-h fecal weight
nor total transit time is a good predictor of the rate of transit through
particular gut segments.
