BACKGROUND:

Plant sterols, in various forms, have been shown to reduce total and LDL-cholesterol concentrations. Particularly controversial at present is the effect of the degree of hydrogenation of the plant sterols on cholesterol-lowering efficacy and the responsible mechanisms.

OBJECTIVE:

Our goal was to examine the effect of supplementation with unesterified plant sterols and stanols on plasma lipid and phytosterol concentrations and cholesterol absorption, synthesis, and turnover.

DESIGN:

Fifteen otherwise healthy hypercholesterolemic subjects consumed each of 4 dietary treatments in a randomized crossover design. Unesterified sterols and stanols were blended into the butter component of the diet at a dosage of 1.8 g/d. The diets contained plant sterols (NS), plant stanols (SS), a 50:50 mixture of sterols and stanols (NSS), or cornstarch (control).

RESULTS:

Plasma total cholesterol concentrations were 7.8%, 11.9%, and 13.1% lower (P < 0.01) in the NS, SS, and NSS groups, respectively, than in the control group. LDL-cholesterol concentrations were 11.3%, 13.4%, and 16.0% lower (P < 0.03) in the NS, SS, and NSS groups, respectively, than in the control group. Plasma triacylglycerols and HDL-cholesterol concentrations did not differ significantly across diets. Cholesterol absorption efficiency was 56.0%, 34.4%, and 48.9% lower (P < 0.001) in the NS, SS, and NSS groups, respectively, than in the control group. The fractional synthesis rate was higher by 45.5% (P < 0.003) in the NSS group than in the control group. Plasma campesterol and sitosterol concentrations were higher (P < 0.01) in the NS group and sitosterol concentrations were lower (P < 0.01) in the SS group than in the control group.

CONCLUSION:

These data indicate that, in their free unesterified form, sterols and stanols lower plasma LDL cholesterol equivalently in hypercholesterolemic persons by suppressing cholesterol absorption.