We investigated the effect of three types of plant sterols (4-desmethylsterols, 4,4′-dimethylsterols, and pentacyclic triterpene alcohols) in three forms (free, esterified with FA, or with phenolic acids) on cholesterol absorption. Plant sterol fractions derived from soybean (99% 4-desmethylsterols), rice bran (70% 4,4′-dimethylsterols), or shea nut (89% pentacyclic triterpene alcohols) were fed to male hamsters (n = 20/group) as free sterols or esterified with FA or phenolic acids (cinnamic or ferulic). Cholesterol absorption was measured after 5-8.5 (mean, 7) wk by a dual-isotope technique. Soybean sterol intake significantly reduced cholesterol absorption efficiency (23%) and plasma total cholesterol (11%). Rice bran sterols tended to lower cholesterol absorption efficiency by 7% and plasma total cholesterol by 5%, whereas shea nut sterols had no effect. In hamsters, dietary 4-desmethylsterols were more effective than 4,4′-dimethylsterols in lowering cholesterol absorption and levels of cholesterol in blood. Pentacyclic triterpene alcohols had no effect on the absorption of cholesterol or on its level in blood. Esterification with FA did not impair the ability of 4-desmethylsterols and 4,4′-dimethylsterols to inhibit cholesterol absorption, whereas esterification with phenolic acids reduced this ability. This study supports the use of 4-desmethylsterols, esterified with FA to increase solubility, as the most effective cholesterol-lowering plant sterols in the diet.

4-Desmethylsterols and -stanols reduce plasma total cholesterol (TC) and LDL cholesterol by inhibition of intestinal cholesterol absorption, while the cholesterol-lowering potential of 4,4 0 -dimethylsterols is less well defined. The present study aimed to compare the effects of 4-desmethylsterols, -stanols, and 4,4 0 -dimethylsterols on plasma and hepatic cholesterol, sterol excretion and bile acid metabolism. Male golden Syrian hamsters were fed diets containing 13 g/100 g fat, 0·08 g/100 g cholesterol and 0 (control), 0·24 or 0·48 % (w/w) esterified 4-desmethylsterols (sterols) and esterified hydrogenated 4-desmethylsterols (stanols) from common vegetable oils or esterified 4,4 0 -dimethylsterols from rice bran oil for 5 weeks. Sterol and stanol esters at the dose of 0·24 % were equally effective and significantly (P,0·05) lowered TC by 15 %, while 0·24 % 4,4-dimethylsterols reduced TC by 10 %. Liver total and esterified cholesterol concentrations were significantly (P,0·05) lowered by 40, 22, 43 and 31 % in hamsters fed 0·48 % sterols, 0·24 % stanols, 0·48 % stanols or 0·48 % dimethylsterols, respectively. Daily faecal bile acid excretion and hepatic cholesterol 7a-hydroxylase activity were not altered, indicating that sterols, stanols and dimethylsterols had no effect on the intestinal re-absorption of bile acids or on hepatic bile acid synthesis. Daily excretion of cholesterol was significantly higher in hamsters fed esterified sterols and stanols, but was only slightly increased in those fed dimethylsterols. The results indicate that esterified sterols and stanols were equally effective in lowering plasma TC and LDL cholesterol, while dimethylsterol esters caused a weaker cholesterol-lowering effect. Sterols and stanols achieve their cholesterol-lowering effect by stimulating faecal cholesterol excretion through inhibiting intestinal cholesterol absorption, but do not affect bile acid excretion. Other mechanisms need to be considered to explain the effect on plasma and hepatic cholesterol of dimethylsterols. Plant sterols, also called phytosterols, are components of a normal diet, mainly coming from plant sources, e.g. vegetable oils, seeds, nuts and grain-based products. The typical consumption of plant sterols with Western diets ranges between 200 and 400 mg/d, whereas the intake of phytostanols, the saturated form of plant sterols, is negligible (Jones et al. 1997). The most common plant sterols are the 4-desmethylsterols b-sitosterol, campesterol and stigmasterol; their saturated counterparts are sitostanol and campestanol.

4-Desmethylsterols and -stanols reduce plasma total cholesterol (TC) and LDL cholesterol by inhibition of intestinal cholesterol absorption, while the cholesterol-lowering potential of 4,4'-dimethylsterols is less well defined. The present study aimed to compare the effects of 4-desmethylsterols, -stanols, and 4,4'-dimethylsterols on plasma and hepatic cholesterol, sterol excretion and bile acid metabolism. Male golden Syrian hamsters were fed diets containing 13 g/100 g fat, 008 g/100 g cholesterol and 0 (control), 0.24 or 0.48% (w/w) esterified 4-desmethylsterols (sterols) and esterified hydrogenated 4-desmethylsterols (stanols) from common vegetable oils or esterified 4,4'-dimethylsterols from rice bran oil for 5 weeks. Sterol and stanol esters at the dose of 0.24% were equally effective and significantly (P<0.05) lowered TC by 15%, while 0.24% 4,4-dimethylsterols reduced TC by 10%. Liver total and esterified cholesterol concentrations were significantly (P<0.05) lowered by 40, 22, 43 and 31% in hamsters fed 0.48% sterols, 0.24% stanols, 0.48% stanols or 0.48% dimethylsterols, respectively. Daily faecal bile acid excretion and hepatic cholesterol 7alpha-hydroxylase activity were not altered, indicating that sterols, stanols and dimethylsterols had no effect on the intestinal re-absorption of bile acids or on hepatic bile acid synthesis. Daily excretion of cholesterol was significantly higher in hamsters fed esterified sterols and stanols, but was only slightly increased in those fed dimethylsterols. The results indicate that esterified sterols and stanols were equally effective in lowering plasma TC and LDL cholesterol, while dimethylsterol esters caused a weaker cholesterol-lowering effect. Sterols and stanols achieve their cholesterol-lowering effect by stimulating faecal cholesterol excretion through inhibiting intestinal cholesterol absorption, but do not affect bile acid excretion. Other mechanisms need to be considered to explain the effect on plasma and hepatic cholesterol of dimethylsterols.