Lack of beneficial effects of wheat bran cereals on cholesterol balance in swine

Abstract

Twenty young (8–10 weeks old and approximately 10 kg) male Yorkshire swine were studied for (1) the effects of the amounts of fat (90, 30, and 0 g butter) added in mash-based diet on serum cholesterol concentrations and fecal neutral steroids and bile acid excretions; (2) the effects of fat in semipurified diets with the same amount of dietary fiber as in mash but derived from wheat bran cereals in the semipurified diets; and (4) the effects of a wheat bran cereal containing a high lignin content. The effects of fat contents on serum cholesterol concentration and fecal steroid excretions were demonstrated in both mash-based diets and in semipurified diets containing wheat bran cereal as the source of dietary fibers. Butter (90 g) added to a mash-based diet resulted in an increase in serum cholesterol concentration and a reduction in fecal steroids as compared to the 0-g butter group. When fat content was varied in a semipurified diet containing wheat bran cereal, serum cholesterol concentrations were elevated during 40 and 20% fat (by calories) diet periods accompanied by the reduction in fecal steroid excretions. On comparing fecal steroid excretions in wheat bran-containing diets and in mash with dietary fiber content of both at 64 g and equal fat contents, wheat bran-containing diets excreted significantly less than mash. Moreover, fecal steroid excretions during wheat bran diets were essentially the same as that of a semipurified diet containing purified cellulose-type fiber as the source of fiber. However, at the low fat content (10% fat by calories), bran-containing diet produced fecal bulk similar to that of mash. A wheat bran cereal containing higher (2.6 times) lignin content than the other did not affect fecal steroid excretion. It appears, therefore, that higher fecal steroid excretion during mash feeding is not principally due to fiber per se but due to factor(s) yet to be named. From our studies on the effects of soy protein, vegetable proteins in mash might be the factor mainly responsible for increased fecal steroid excretions.