Effect of plant sterols and exercise training on cholesterol absorption and synthesis in previously sedentary hypercholesterolemic subjects

Plant sterols combined with exercise beneficially alter lipid profiles in hypercholesterolemic adults. Although the mechanism by which plant sterols favorably modulate lipid levels is well established, no trial to date has examined the effect of exercise, alone or combined with plant sterols, on cholesterol kinetics. Thus, the current objective was to examine the effects of exercise, plant sterols, and the combination of exercise and plant sterols on cholesterol absorption and synthesis. In an 8-week, parallel-arm trial, 84 subjects were randomized to 1 of 4 interventions: plant sterols combined with exercise, plant sterols, exercise, or control. Diets were not controlled. Total cholesterol and triglyceride levels decreased (P<0.01) by 7.7% and 11.8%, respectively, whereas high-density lipoprotein (HDL) cholesterol levels increased (P<0.01) by 7.5% in the combination group. Mean posttreatment low-density lipoprotein (LDL) cholesterol levels decreased (P<0.01) by 0.30 mmol/L in the combination group. Cholesterol absorption was 16% lower (P<0.01) in the combination group and 18% lower (P<0.01) in the plant sterol group, when compared with control. Exercise had no effect on cholesterol absorption. Nonsignificant increases in cholesterol synthesis rates of 63% (0.084+/-0.014 pools/day), 59% (0.075+/-0.013 pools/day), and 57% (0.072+/-0.011 pools/day) were observed in the combination, exercise, and plant sterol groups, respectively, relative to the control group (0.031+/-0.019 pools/day). LDL cholesterol levels correlated with cholesterol absorption, as represented by the area under the deuterium enrichment curve (r=0.23, P=0.05), and with percent absorption relative to control (r=0.25, P=0.03). These findings suggest that exercise does not modulate lipid levels by altering to cholesterol absorption or synthesis, whereas plant sterols favorably alter levels of LDL cholesterol by suppressing intestinal absorption.