Effect of Oral Administration to Rats of Various Undigestible Saccharides on Fecal pH, Water Contents and Enzyme Activities

We investigated the effects of oral administration of undigestible oligoand polysaccharides to rats on microbial fermentation products and fecal enzyme activities. The fecal pH values were decreased by feeding diet containing arabinogalactan (AG), kestose (Kes) and nystose (Nys). The fecal moisture was significantly increased by feeding polydextrose (PD), xylooligosaccharide (XO), glucuronosyl xylooligosaccharide (GXO), citrus pectin (CP) and apple pectin (AP) diet. Oligoand polysaccharides in the diet resulted in a decrease in fecal ƒÀ-glucosidase, ƒÀ-glucuronidase and urease activities measured at a constant pH (7.2). PD-containing diet, exceptionally, increased fecal ƒÀ-glucosidase activity threeto fourfold. Furthermore, fecal enzyme activities were assayed at the fecal pH to assume their actual activities in the colon. These activities were distinctly altered; particularly, ƒÀ-glucosidase activity in rats fed PD increased and all of the enzyme activities assayed in rats fed Kes and Nys were significantly decreased. These results suggest that the actual enzyme activities of intestinal bacteria should be assayed not at their optimal pHs, but at intestinal pHs. The effects of ten oligoand polysaccharides on the intestinal environment are discussed in connection with the reduction in the incidence of colon cancer by daily intake