Artificial fiber complexes composed of cellulose and guar gum or psyllium may be better sources of soluble fiber for rats than comparable fiber mixtures.

Three fiber complexes composed of cellulose and the same weight of guar gum, cornstarch or psyllium were constructed as three-dimensional networks of cellulose fiber filled with the soluble components. Physiological properties of these fiber complexes were examined in comparison with a mixture of powdered cellulose and the corresponding polysaccharides at a ratio of 1:1 in rats. Another group of rats was fed a fiber-free diet. Body weight gain in the guar gum-cellulose mixture group, but not in guar gum-cellulose complex group, was lower than that of the fiber-free group. The cecal walls in the groups fed the guar gum-cellulose and psyllium-cellulose mixture diets were heavier than those in the corresponding fiber complex-fed groups. Weights of the small intestinal wall and ileal mucosa were also greater in the guar gum-cellulose mixture-fed group than in the guar gum-cellulose complex-fed and the fiber-free diet-fed groups. Fermentable energy in dietary fiber estimated from fecal energy excretion, short-chain fatty acid contents and in vitro short-chain fatty acid production rates in the cecum of the complex-fed groups were similar to those in the fiber mixture-fed groups. However, butyric acid content and production rate in the group fed the guar gum-cellulose complex were markedly higher than in the other groups. The lowering effects of guar gum-cellulose and psyllium-cellulose mixtures on plasma cholesterol concentration tended to be greater than those of guar gum-cellulose and psyllium-cellulose complexes. These findings demonstrate that the artificial fiber complexes supply soluble fibers without increasing mechanical stress to the intestines and decreasing cecal fermentation.