[The cholesterol-lowering effect of black beans (Phaseolus vulgaris, L.) without hulls in hypercholesterolemic rats]

The cholesterol-lowering property of beans has been shown in several studies. The propose of the present work was to investigate the effect of black beans (Phaseolus vulgaris, L.) without hulls on blood cholesterol of hypercholesterolemic rats. Four groups of 8 male rats, Wistar strain, initial body weight of 200 g were kept at +/- 25 degrees C in a light-dark cycle of 12 h, for 28 days. The group Standard received a basal casein diet. Group Control received the basal diet added of 1% cholesterol plus 0.1% cholic acid. The group BB received a diet similar to the Control, substituted by 30% black beans, on dry-weight. The group SBB received black beans without hulls, equivalent to 30% of whole beans. The addition of cholesterol and cholic acid raised blood cholesterol levels of rats on Control diet by 58%, in relation to the Standard. BB diet reduced blood cholesterol by 15% (non-significant-NS) and SBB diet reduced (p < 0.05) by 35%, in relation to the Control diet. The levels of HDL-cholesterol were reduced (p < 0.05) by both bean diets. SBB diet promoted a higher excretion of fecal cholesterol, compared to the Control. This suggests that beans without hulls promote a higher cholesterol output and that the whole beans, although had lowered blood cholesterol (NS), kept it in the enterohepatic circulation. The hypocholesterolemic compounds of beans seem to be located in the inner part of the grain. Further studies are necessary to identify these compounds and to elucidate their mechanisms of action.