Fermentable property of dietary fiber may not determine cecal and colonic mucosal growth in fiber-fed rats

Abstract

Differences in cecal and colonic mucosal weight, DNA, RNA, and protein content were observed after feeding fiber-free or cellulose, sugar-beet fiber (SBF), psyllium- and guar gum-containing diets in Sprague-Dawley male rats in regard to fermentable and physical properties of the dietary fiber. In rats fed a low fermentable viscous fiber, psyllium, protein, RNA, and DNA contents in the cecal mucosa were greater than those in the fiber-free and two insoluble fiber groups. The effects of psyllium feeding on the colonic mucosa were much greater than those of the other groups, except RNA and DNA content in the SBF group. In rats fed a highly fermentable viscous polysaccharide, guar gum, changes in the cecal protein, RNA and DNA content were very similar to those in the psyllium group. In contrast, guar gum feeding did not influence any indications of the colonic mucosa. The ingestion of cellulose did not affect the cecal and colonic mucosa. Effects of a highly fermentable insoluble fiber, SBF, on the cecal mucosa were intermediate between cellulose and soluble fiber groups. Colonic DNA pool in the SBF group was high and comparable to that in the psyllium group. The present study shows that fermentable property is not sole determinant of the mucosal growth of the large intestine by dietary fiber, and the effects of physical stress by dietary fiber on the cecal and colonic mucosa may be greater than stimulation of fermented products.