Modulation of plasma lipid levels and cholesterol kinetics by phytosterol versus phytostanol esters

It has been suggested that phytosterol and phytostanol esters possess simil ar cholesterol-lowering properties, however, whether mechanisms responsible are identical has not been addressed. To address this question, cholestero l plasma levels, absorption, biosynthesis, and turnover were measured in 15 hypercholesterolemic subjects consuming prepared diets each over 21 d usin g a crossover design, Diets contained either i) margarine (M), ii) margarin e with phytosterol esters (MSE) (1.84 g/d), or iii) margarine with phytosta nol esters (MSA) (1.84 g/d), Cholesterol absorption was measured using the ratio of [C-13]cholesterol(oral):D-7-cholesterol(IV); biosynthesis using D incorporation from D2O and turnover by D-7-cholesterol(IV) decay rates. Pla sma total cholesterol level at d 21/22 was lower (P < 0.05) for MSE (13.4%) but not MSA (10.2%) versus M (6.0%) diets. Plasma low density lipoprotein- cholesterol (LDL-C) mean reductions at d 21/22 were larger (P < 0.05) for M SE (12.9%) arid MSA (7.9%) compared with M (3.9%). Plasma TG and high densi ty lipoprotein-cholesterol (HDL- C) levels did not differ across diets. Cho lesterol absorption was reduced (P < 0.05) 36.2 and 25.9% at d 21 for MSE a nd MSA versus M, while cholesterol biosynthesis was reciprocally increased (P < 0.05) 53.3 and 37.8% for MSE and MSA versus M, respectively. Cholester ol turnover was not influenced by diet, These data indicate that plant ster ol and stanol esters differentially lower circulating total and LDL cholest erol levels by suppression of cholesterol absorption in hypercholesterolemi c subjects. Modulation of plasma lipid levels and cholesterol kinetics by p hytosterol versus phytostanol esters.