Effects of saponins on bile acids and plasma lipids in the rat

Abstract

1. The effects of feeding isolated saponins on plasma lipid concentrations and on concentrations of biliary and faecal bile acids and neutral sterols were studied in the rat.2. The animals were given one of four diets, i.e. a standard low-cholesterol synthetic diet, the diet+10 g saponins/kg, the diet+10 g cholesterol/kg, the diet+10 g cholesterol+10 g saponins/kg.3. Saponins partially reversed the hypercholesterolaemia caused by the high-cholesterol diet and increased both the rate of bile acid secretion and the faecal excretion of bile acids and neutral sterols. The proportionate contribution of the primary bile acids (particularly chenodeoxycholic) to faecal excretion was also increased by saponins.4. The results are discussed in relation to the hypothesis that saponins act by inducing the adsorption of bile acids by dietary fibre.

Cholesterol and bile acid balance in Macaca fascicularis. Effects of alfalfa saponins.

“…The decrease in the distribution of secondary bile acids has also been observed by Oakenfull et al (34) in rats. These findings are compatible with the increased acidic steroid excretion observed in rats after the addition of fiber to the diet (27,35), if we assume that saponins are involved in the binding of bile acids to plant fiber, as has been surmised by Oakenfull and Fenwick (4) and 'Hood et al (22); adsorption of bile acids by plant fiber may also be mediated by pectic substances, however (36).…”

“…That alfalfa top saponins increase bile acid excretion has not been reported until now, but a similar phenomenon has been observed in rats fed a commercial saponin (34). The decrease in the distribution of secondary bile acids has also been observed by Oakenfull et al (34) in rats.…”

Effects of dietary soybean globulins on plasma and liver lipids and on fecal excretion of neutral sterols in rats.

“…Though contradictory, a few investigators still ascribe the cholesterol-lowering effect of soybean protein to the nonproteinous components such as saponin, but not to protein itself (9). Since it is also known that the two major globulin fractions, 7S and 11S globulins, contain different amounts of carbohydrates, use of fractionated proteins should provide a hint for the resolution of this conflicting observation.…”

“…The present study also provided no consistent correlation between the contents of carbohydrates in the protein preparations and plasma cholesterol levels. The saponin-hypothesis could thus be discarded (9).…”

Effects of Platycodon Grandiflorum Feeding on Serum and Liver Lipid Concentrations in Rats with Diet-Induced Hyperlipidemia.

“…may be partially attributed to its dietary fiber. On the other hand, it has been reported that dietary proteins from various plants (13), and dietary purified saponin (14), or saponin-rich food such as soya-bean protein (15) have hypocholesterolemic effects. In this study, the possibility that some minor components such as plant protein and saponin are partially responsible for these effects cannot be excluded.…”