The effect of the polysaccharide composition and structure of dietary fibers on cecal fermentation and fecal excretion.

The fermentation of dietary fibers gives a clue to their mode of action. Wheat bran and gum tragacanth increase stool weight but have no effect on serum cholesterol or on hydrogen excretion. Gum arabic and pectin in the form of raw carrot have no effect on stool weight but decrease serum cholesterol and are associated with an increase in breath-hydrogen excretion. Other fiber sources like gum karaya have no effect on stool weight, serum cholesterol, or breath hydrogen. There are no correlations between the chemical composition and structure of the fibers studied and their physiological effects.