Similar serum plant sterol responses of human subjects heterozygous for a mutation causing sitosterolemia and controls to diets enriched in plant sterols or stanols.

objectiveWe investigated the serum phytosterol responses of heterozygous relatives of sitosterolemia patients to diets enriched in phytosterols or stanols.

designRandomized double-blind crossover design.

settingMuenster, Germany. SUBJECTS: Eight heterozygous and 13 control subjects were recruited. One heterozygote and three controls dropped out.

interventionsSeven heterozygotes and 10 controls received daily portions of margarine containing 2 g of plant sterols, 2 g of stanols or a control margarine for 6 weeks each in a randomized order. These phases were intercepted by wash-out periods of 6 weeks each.

resultsCompared to the control period, serum phytosterol concentrations increased overall by more than 20% when subjects consumed the plant sterol margarine (F((1,15))=8.719, P=0.01), with no significant difference between heterozygotes (mean +14.5 (s.d. 17.2) micromol/l, +23.0%) and controls (+4.9 (9.9) micromol/l, +20.5%; F((1,15))=2.168, P=0.162), but decreased when subjects consumed the stanol-enriched margarine (F((1,15))=12.124, P=0.003), again to a similar extent in heterozygotes (-34.2 (41.2) micromol/l, -54.2%) and controls (-12.2 (9.2) micromol/l, -50.6%; F((1,15))=2.729, P=0.119). The lowest total serum concentrations of cholesterol and phytosterols were seen after the diet enriched in stanols. Serum stanol concentrations increased on this diet, but on a very low level and never exceeded 0.05% of serum cholesterol levels in any subject.

conclusionsSerum phytosterol concentrations increased only moderately in heterozygotes consuming a diet enriched in phytosterols, indicating that they retained considerable capacity to excrete phytosterols even at higher intakes.