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

Objective: We investigated the serum phytosterol responses of heterozygous relatives of sitosterolemia patients to diets enriched in phytosterols or stanols. Design: Randomized double-blind crossover design. Setting: Muenster, Germany. Subjects: Eight heterozygous and 13 control subjects were recruited. One heterozygote and three controls dropped out. Interventions: Seven 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. Results: Compared 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) mu mol/ l, +23.0%) and controls (+4.9 (9.9) mu mol/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) mu mol/l, -54.2%) and controls (-12.2 (9.2) mu mol/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. Conclusions: Serum 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. Sponsorship: Supported by a grant of the Stifterverband fur die Deutsche Wissenschaft (project number TS022/12372/2002) to MK.