RESUMEN
Feeding of margarines containing sitostanol (CAS 19466-47-8), sitostanol acetate (CAS 73052-08-1), sitostanol oleate (CAS 107615-79-2), or placebo (equivalent of 0.5 g of sitostanol t.i.d) on cholesterol absorption and serum lipids were studied in 10 normolipemic volunteers in a randomized double blind cross-over trial. The study was divided into an open one-week run-in phase and four one-week treatment periods. Each treatment week was followed by a two-week washout period. Measurements of cholesterol absorption was performed by the continuous isotope feeding method using stable isotope labeled cholesterol and sitostanol. Cholesterol absorption during placebo, sitostanol, sitostanol acetate and sitostanol oleate feeding averaged 41.6 +/- (SD) 8.0, 10.2 +/- 6.6, 17.0 +/- 6.7, and 20.5 +/- 5.3%, respectively (p < 0.001 for all against placebo). Low density lipoprotein (LDL) cholesterol was proportionally reduced by 22 (p < 0.001), 14 (p < 0.05), and 8% (ns). Absorption efficiency was significantly lower with free sitostanol than with sitostanol acetate or oleate (p < 0.01). Percent reduction in cholesterol absorption with all preparations compared to placebo correlated positively with the percent reduction in LDL cholesterol (r = 0.404; p < 0.03). The results indicate that unesterified sitostanol is more effective in inhibiting cholesterol absorption and reducing LDL cholesterol than the acetate or oleate esters.