Phytosterols, Ezetimibe, and Cholesterol Metabolism

Regulation of Cholesterol Absorption: LDL Cholesterol Response to a Combination of Phytosterols and Ezetimibe (Phyto-3)

Phytosterols and ezetimibe each reduce intestinal cholesterol absorption by 30-55% but appear to have different mechanisms of action. The investigators' hypothesis is that phytosterols and ezetimibe given together will block cholesterol absorption in an additive fashion. In a randomized, placebo-controlled crossover trial the effects of placebo, ezetimibe treatment and ezetimibe plus phytosterol treatment will be measured.

The investigators will perform a randomized, placebo-controlled crossover feeding study in 25 subjects with greater than ideal levels of LDL cholesterol who do not require anti-cholesterol drug treatment. Subjects will consume a baseline diet provided by a feeding center that is deficient in phytosterols for three periods of 21 days separated by 7-day washout periods. Treatments will be given in random order During period B placebo phytosterols and placebo ezetimibe will be given; during period C placebo phytosterols and active ezetimibe will be given; during period A active phytosterols and active ezetimibe will be given. Study endpoints are fecal cholesterol excretion and percent cholesterol absorption determined by gas chromatography/mass spectrometry and circulating LDL cholesterol.

Inclusion Criteria:

• Male or female of any race or ethnicity between 18 to 80 years of age;
• Body mass index between 20 - 35 kg/m2;
• LDL-cholesterol between 130 - 189 mg/dL based on the average of duplicate screening measures. If the two LDL-C levels differ by more than 30 mg/dL, a third test will be scheduled with all three results averaged;
• Free of chronic disease;
• Willing to eat only the foods that are provided by the Center during the diet periods;
• Willing to abstain from the consumption of alcohol for 48-hours prior to blood draw days;
• Willing to drink no more than 5 cups of caffeine-containing beverages a day.

Exclusion Criteria:

• Age < 18 or > 80 years;
• Based on duplicate screening laboratory values: 1)LDL-C >=190 mg/dL; 2)TG >=250 mg/dL;3)blood pressure >= 160 mm Hg systolic or 95 mm Hg diastolic;
• Documented presence of atherosclerotic disease;
• Diabetes mellitus;
• Renal, hepatic, endocrine, gastrointestinal, hematological or other systemic disease;
• Body mass index > 35;
• For women, pregnancy, breast feeding or postpartum < 6 months;
• For women, peri-menopausal;
• For women, sexually active but not practicing effective birth control methods;
• History of drug or alcohol abuse;
• History of depression or mental illness requiring treatment or medication within the last 6 months;
• multiple food allergies or significant food preferences or restrictions that would interfere with diet adherence;
• Chronic use of over-the-counter medication which would interfere with study endpoints including laxatives and antacids;
• Lifestyle or schedule incompatible with the study protocol;
• Planned continued use of dietary supplements through the study trial;
• Taking any lipid-lowering, or other medications known to affect blood cholesterol.