In view of the increasing incidence of arteriosclerosis and coronary heart disease caused by hypercholesterolemia, some food components are receiving attention because of their ability to normalize cholesterol metabolism. In this study we examined the mechanisms by which dietary fiber and taurine reduce the plasma cholesterol concentration by focusing on their effects in the digestive tract. We found that sugar beet fiber (BF), which is a high-fermentative dietary fiber, lowered plasma cholesterol concentrations in rats, and that passage through the lower digestive tract, especially the cecum, was necessary for initiating this effect. Moreover, the effect was related to fermentation of BF in the large intestine. The by-products of fermentation that induce this effect have not yet been determined. However, in addition to fermentation of BF in the large intestine, increased bile acid excretion into feces is critical for induction of the plasma cholesterol-lowering effect. We also confirmed that bile acid excretion into feces enhanced by taurine feeding plays a role in the plasma cholesterol-lowering effect. The inhibition of bile acid absorption, but not the induction of cholesterol 7α-hydroxylase, seems to be related mainly to an increase of bile acid excretion induced by taurine. Our findings indicate that the reduction of plasma cholesterol concentrations results from fermentability of dietary fiber in the lower digestive tract and inhibition of bile acid absorption from the distal ileum and lower digestive tract by taurine.