Comparative effects of four legume species on plasma lipids and faecal steroid excretion in hypercholesterolaemic pigs

Abstract

The effect of four species of legume seeds on plasma cholesterol levels and faecal steroid excretion was studied in pigs. Thirty-six growing boars were randomly allocated in groups of six to six diets which they ate continuously for 42 d. The diets fed were: 1, a semi-purified (SP; control group 1) diet; 2, SP 10 g cholesterol/kg (control group 2); 3, 4, 5, 6, SP + cooked legumes (70:30, w/w; respectively baked beans ( Phaseolus vulgaris ), peas ( Pisum sativum ), lentils ( Lens culinaris Medik.), butter beans ( Phaseolus lunatus )) + 10 g cholesterol/kg. Fasting blood samples were taken on days 0, 14, 28, and 42 for the determination of total plasma cholesterol, high-density-lipoprotein (HDL)-cholesterol and triacylglycerols. Between days 7 and 11 and days 28 and 32 complete 5 d faecal collections were made for the measurement of neutral, acidic and conjugated steroids. After 42 d total cholesterol and HDL-cholesterol levels were raised significantly in all groups, but to different extents. In comparison with control group 2, diet-induced hypercholesterolaemia was significantly inhibited in the groups consuming baked beans, peas and butter beans, although HDL-cholesterol levels were maintained. Faecal steroid excretion by the legume groups was not significantly different from that of control group 2. The results suggest that the mechanism for the hypocholesterolaemic effect does not involve increased hepatic bile acid synthesis and thereby increased cholesterol clearance via the intestinal route.