A comparison of hypocholesterolemic activity of beta-sitosterol and beta-sitostanol in rats.

The hypocholesterolemic activity of beta-sitosterol and its hydrogenated product, beta-sitostanol (dihydrositosterol or stigmastanol) has been compared in young male rats. When cholesterol was included in the diet, sitostanol consistently exhibited significantly greater hypocholesterolemic activity than sitosterol. There were no apparent differences in the effects of the sterol and the stanol on the concentration of liver cholesterol and triglyceride. Increases in plasma triglyceride due to feeding sitosterol were not observed with sitostanol. Incorporation of dietary sitostanol into plasma, liver and other tissues was always negligible, and thus this stanol was almost completely recovered in feces, while there was considerable deposition of sitosterol (mean fecal recovery being 85% to 92%). The increase in fecal output of dietary cholesterol was significantly greater with the stanol than with sterol. There was no demonstrable negative effect on growth and weight of major visceral tissues in rats fed the sterol as well as the stanol. These observations together with those reported previously indicate that hydorgenation of phytosterols is a novel approach to enhance their hypocholesterolemic activities without influencing the relative safety of the initial sterols.