Dietary lectin lowers serum cholesterol and raises fecal neutral sterols in cholesterol-fed rats

Abstract

This study examined the influence of a low level of dietary lectin (0.34%), at a dose that did not affect body weight or food intake, on the concentration of serum cholesterol and fecal excretion of neutral sterols in rats fed a diet containing 0.50% cholesterol and 0.13% sodium cholate for 12 d. In experiment 1, rats fed a diet with 0.34% lectin, concanavalin A, had significantly lower concentrations of serum total cholesterol and hepatic cholesterol, a higher ratio of HDL-cholesterol to total cholesterol, enhanced excretion of fecal neutral sterols and reduced apparent cholesterol absorption or digestibility as compared with rats fed a diet without lectin. Fecal excretion of acidic sterols was unaffected by dietary lectin. In contrast, dietary 0.34% lectin had no significant effect on concentrations of serum total protein or glucose. In experiment 2, we examined whether the cholesterol-lowering activity of the lectin was responsibility for its carbohydrate-binding activity. The effect of dietary lectin on concentrations of serum and hepatic cholesterol and excretion of fecal neutral sterols was prevented by simultaneous administration of methyl-α-D-mannopyranoside with specific affinity for the carbohydrate-binding sites of the lectin. These results suggest that dietary lectins might reduce concentrations of serum and hepatic cholesterol by a mechanism involving higher excretion of neutral sterols and that these alterations might be associated with the carbohydrate-binding activity of lectin.