Effect of esterified 4-desmethylsterols and -stanols or 4,4′-dimethylsterols on cholesterol and bile acid metabolism in hamsters

Abstract

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.

Corn fiber oil and sitostanol decrease cholesterol absorption independently of intestinal sterol transporters in hamsters

“…The effects of sitostanol on TGs have been variable due to the different amounts of dietary cholesterol and fats used in different animal models. Similar to what was observed in the present results, Trautwein et al [32] showed a 25% decrease in TG levels by 0.48% dietary stanols in hamsters ingesting 0.08% cholesterol-containing diets.…”

Fish oil fatty acid esters of phytosterols alter plasma lipids but not red blood cell fragility in hamsters

“…In other studies in hamsters, feeding plant sterol esters has resulted in decreased total cholesterol concentrations (34)(35)(36). However, in most of these studies showing a beneficial impact of free or esterified plant sterols in hamsters, the amount of cholesterol in the diet was lower (0.08-0.09%) (34,35) than in the present experiment (0.25%). It is therefore possible that the hypercholesterolemic impact of a greater intake of cholesterol in the present study may not have been counteracted completely by plant sterol consumption.…”

Rice bran oil and oryzanol reduce plasma lipid and lipoprotein cholesterol concentrations and aortic cholesterol ester accumulation to a greater extent than ferulic acid in hypercholesterolemic hamsters

“…Because ferulic acid feeding did not change cholesterol excretion, it probably did not disrupt micelle formation and, thus, did not inhibit vitamin E absorption. Another possible explanation of why the oryzanol produced significantly lower plasma LPHs while reducing plasma vitamin E levels simultaneously is the possibility that oryzanol is metabolized by digestive enzymes in the GI tract of hamsters into free ferulate and free sterols [67], of which the free ferulate is then absorbed and acts as an antioxidant within the plasma, and the free sterol inhibits the cholesterol absorption within the GI tract, thereby lowering blood cholesterol levels [68,69].…”