Long-term feeding of unavailable carbohydrate gelling agents. Influence of dietary concentration and microbiological degradation on adaptive responses in the rat

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Abstract
Guaran, tragacanth, gum arabic, carrageenan, gum karaya, and methylcellulose were used in a long-term feeding study to evaluate their effects upon adaptive responses of nutritionally controlled parameters in rats by feeding a fiber-free diet containing increasing additions of polysaccharides. In general, supplements reduced weight increases due to lower energy intakes. Only in the case of microbiologically inert polysaccharides the dilution of the energy density was partially compensated by an increased food intake. Neither of the polysaccharides fed, however, decreased energy utilization. All polysaccharides similarily increased small intestinal length up to about 30% without grossly altering mucosal protein and DNA per unit of length. Concerning their effects on the colon and the cecum, polysaccharides behaved differentially according to their accessibility to microbiological degradation. Inert polysaccharides exerted a more pronounced effect on the colon whereas the others mainly increased cecum weight. Degree and locus of the observed changes are determined mainly by the dietary concentration of the polysaccharides and their accessibility to bacterial degradation within the intestinal tract.