ABSTRACT
In rabbits the fecal excretion of cholesterol and its bacterial metabolites (3,4) and of bile acids (4,5) is decreased almost immediately after soybean protein is replaced by casein, and before the concentration of serum cholesterol is increased. Table 7-2 shows the effect of dietary soybean protein versus casein on fecal excretion of steroids in rabbits and rats. The time course of excretion (4,5) suggests that effects of the dietary proteins on the enterohepatic circulation of bile acids and cholesterol is at least one of the primary features of protein-induced changes in serum cholesterol concentrations. Dietary proteins do not influence the biliary efflux of bile acids and neutral steroids (8,9). This would imply that soybean protein versus casein affects intestinal absorption of cholesterol and bile acids.
