SERUM LEVELS, ABSORPTION EFFICIENCY, FECAL ELIMINATION AND SYNTHESIS OF CHOLESTEROL DURING INCREASING DOSES OF DIETARY SITOSTANOL ESTERS INHYPERCHOLESTEROLEMIC SUBJECTS

1. Serum cholesterol reduction and changes in cholesterol metabolism w ere studied during rapeseed oil feeding without and with increasing am ounts of sitostanol trans-esterified with rapeseed oil fatty acids and dissolved in rapeseed oil mayonnaise. Fifteen mildly hypercholesterol aemic subjects replaced 50 g of their usual dietary fat by 50 g of rap eseed oil fat mayonnaise for 6 weeks followed by randomization so that eight subjects continued on rapeseed oil mayonnaise alone (control gr oup) for 15 weeks and seven on rapeseed oil mayonnaise with a small do se of sitostanol ester (800 mg/day of sitostanol) for 9 weeks followed by 6 weeks with higher dose of sitostanol ester (2000 mg/day of sitos tanol). 2. During the rapeseed oil period the reduction in serum low-d ensity lipoprotein cholesterol was 14% from the home diet. The control -adjusted reduction by the low sitostanol ester dose was 7.4% (not sig nificant) and by the higher dose it was 15.7%. 3. The low dose of sito stanol ester had no consistent effect on cholesterol precursors or cho lestanol in serum, reduced serum levels of campesterol and sitosterol by 28.2%, and 23.6%, respectively, and reduced cholesterol absorption efficiency significantly from 28.7% to 23.4%. In accordance, faecal ex cretion of neutral and particularly endogenous neutral sterols increas ed (16.7% and 19.7%, respectively), but faecal cholesterol elimination and cholesterol synthesis were only insignificantly increased. 4. Dur ing the high dose of sitostanol ester the high-density lipoprotein-to low-density lipoprotein-cholesterol ratio increased. Serum levels of c holesterol precursor sterols, indicators of cholesterol synthesis, inc reased up to 12%, whereas those of cholestanol were slightly decreased and those of campesterol and sitosterol values were further reduced b y 30% and 25.6%, respectively. 5. Associations of serum plant sterols and cholesterol precursors with cholesterol absorption efficiency and synthesis and the sitostanol-ester-induced changes in serum campestero l and lathosterol proportions with