Effects of Buttermilk on Serum LDL Cholesterol Concentrations

The Effects of Buttermilk With or Without Lutein-enriched Egg Yolk on the Serum LDL Cholesterol Concentration of Slightly Hypercholesterolaemic Volunteers

Rationale and objective:

Based on the results of a pilot study, the objective of the present study is to evaluate whether buttermilk lower serum LDL cholesterol concentrations and can prevent the serum LDL cholesterol raising effects of eggs.

Study Design:

The study has a randomized placebo-controlled factorial 2x2 design. The total study duration is 14 weeks, consisting of a 2 weeks run-in period and a 12 weeks experimental period. Subjects will be stratified for age, gender and BMI over the experimental groups.

Study population:

One hundred and eight healthy male and female subjects, aged 18-70 years, with slightly elevated serum total cholesterol concentrations (5.5-8.0 mmol/l).

Intervention:

During the entire study period, volunteers are instructed to consume a diet according to the Dutch dietary guidelines (35 en% fat (10 en% saturated fat), 50-55 en% carbohydrates). During the two weeks run-in period all subjects will drink daily at lunch 100 mL skimmed milk. During the 12 weeks experimental period, a first group of subjects will continue drinking the skimmed milk (control group), while a second group will consume a low-fat buttermilk, a third group skimmed milk enriched with egg-yolk, and a fourth group egg-yolk incorporated into a low-fat buttermilk based beverage. The egg-yolk will be enriched in lutein. Whole egg consumption (others than provided by us) is not allowed during the entire study.

Main study parameters/endpoints:

Measurements will be performed during the run-in period (days 0, 11 and 14) and during the experimental period (days 56, 95 and 98). The main effects (egg-yolk and buttermilk consumption) will be calculated as the absolute differences between values obtained at the end of the experimental (average days 95 and 98) and run-in (average days 11 and 14) periods. The primary endpoint is the change in serum LDL cholesterol concentrations. Secondary endpoints are changes in serum total and HDL cholesterol, triacylglycerol, apoA-I, apoB and hsCRP concentrations.

Inclusion Criteria:

• Aged between 18 and 70 years
• Fasting serum total cholesterol between 5.5 - 8.0 mmol/l
• Fasting plasma glucose < 7.0 mmol/l
• BMI between 25-30 kg/m2
• non-smoking
• Willingness to abstain for the duration of the study from egg consumption

Exclusion Criteria:

• unstable body weight (weight gain or loss >3 kg in the past 3 months)
• allergic for eggs or egg-rich products
• allergic or intolerant for cow-milk (lactose) based products
• indication for treatment with cholesterol-lowering drugs according to the Dutch Cholesterol Consensus
• use of medication or a diet known to affect serum lipid or glucose metabolism - active cardiovascular disease (for instance congestive heart failure) or recent (<6 months) event, such as acute myocardial infarction or cerebro-vascular accident
• not willing to stop the consumption of vitamin supplements, fish oil capsules or products rich in plant stanol or sterol esters 3 weeks before the start of the study
• men: consumption of >21 alcohol consumptions a week
• women: consumption of >14 alcohol consumptions a week
• abuse of drugs
• pregnant or breastfeeding women
• participation in another biomedical study within 1 month prior to the screening visit
• having donated blood (as blood donor) within 1 month prior to the screening visit or planning to do so during the study
• impossible or difficult venipuncture as evidenced during the screening visits