Dietary polydextrose affects the large intestine in rats

We compared the effects of dietary polydextrose with those of dietary fibers on the luminal pH and morphology of the large intestine in rats. In Experiment 1, animals were fed diets supplemented with two levels (5 and 10 g/100 g) of polydextrose or dietary fiber (cellulose or galactomannan derivatives) for 52 d. Polydextrose and galactomannan derivatives significantly lowered large intestinal pH and increased the cecal weight and surface area compared with cellulose. However, the thickness of the cecal muscular layer was significantly less in the polydextrose-fed groups than in the cellulose-fed groups. In Experiment 2, rats were fed either a fiber-free diet or a diet containing 5, 10 or 20 g/100 g polydextrose for 92 d. Dietary polydextrose significantly acidified the cecal contents and promoted cecal mucosal growth but thinned the cecal muscular layer. The shape of colonic mucosa of the group fed the 20 g/100 g polydextrose diet was clearly different from that of the group fed the fiber-free diet. These findings indicate that the effect of polydextrose on the morphology of the large intestine is different from the effect of dietary fibers.