Dietary Fiber, Inulin, and
Oligofructose:
a Review Comparing their Physiological Effects
Roberfroid M.
[published erratum appears in Crit Rev Food Sci Nutr
1993;33(6):553]
Critical Reviews in Food Science and Nutrition, 1993,
33(2):103-48
Abstract:
Dietary fiber is a general term. It covers a wide variety of
substances that belong to the family of carbohydrates that resist
hydrolysis by human alimentary enzymes but are fermented by
colonic microflora.
The main physiological effects of dietary fiber are
|
Primarily on gastric emptying and small
intestinal transit time, resulting in an improved glucose tolerance and a decreased digestion of starch. |
|
Second, on colonic transit time and large
bowel functions due to fermentation by ceco-colonic microbial flora or bulking action. |
The so-called soluble dietary fibers are fermented to a large extent by a wide variety of anaerobic bacteria that result in an increase in bacterial biomass, an increase in fecal mass, a change in intracolonic pH, and production of short chain fatty acids and various gases as metabolic end products. The insoluble fibers are only marginally fermented: they serve almost exclusively as bulking agents that result in shorter transit time and increased fecal mass.
The short chain fatty acids resulting from the colonic fermentation of dietary fiber are largely absorbed via the portal blood and reach both the liver and the peripheral tissues. They induce changes in glucose and fat metabolism leading to post-prandial hypoglycemia and long-term hypolipidemia.
