Plant sterols and stanols (also called phytosterols and phytostanols) are structurally related to cholesterol, but absorbed to a much lesser extent. Due to this structural similarity, plant sterols and stanols inhibit intestinal cholesterol absorption and lower serum LDL cholesterol concentrations by about 10% at daily intakes of 2.5 g. Plant sterol- and stanol-enriched food products are therefore widely available on the market to lower the risk for coronary heart disease. Plant sterols can undergo oxidation, which results in the formation of oxyphytosterols. Animal studies have now suggested that oxyphytosterols are atherogenic. Although oxyphytosterols have been identified in human serum samples, the effect of an increased intake of plant sterols on serum oxyphytosterol concentrations in humans is not known. On the other hand, plant stanols cannot be oxidized and lower not only cholesterol absorption, but also plant sterol absorption.

The major objective of the present study is to examine the effects of dietary plant sterols and stanols on fasting serum concentrations of oxyphytosterols. The minor objective is to investigate the effects of these products on postprandial serum oxyphytosterol concentrations.

Inclusion Criteria:

• Body Mass Index (BMI) between 20-30 kg/m2
• mean serum total cholesterol < 7.8 mmol/L
• mean serum triacylglycerol < 3.0 mmol/L
• mean plasma glucose < 6.1 mmol/L

Exclusion Criteria:

• unstable body weight (weight gain or loss > 3 kg in the past two months)
• active cardiovascular diseases like congestive heart failure or recent (<6 months) event (acute myocardial infarction, cerebral vascular incident)
• severe medical conditions that might interfere with the study such as epilepsy, asthma, chronic obstructive pulmonary disease, inflammatory bowel disease and rheumatoid arthritis
• indication for treatment with cholesterol-lowering drugs according to the Dutch Cholesterol Consensus
• use of medication such as corticosteroids, diuretics or lipid lowering therapy
• abuse of drug or alcohol (>21 units per week)
• not willing to stop the consumption of vitamin supplements, fish oil capsules or products rich in sterol or stanol esters 4 weeks before the start of the study (wash-in period)
• use of an investigational product within another biomedical study within the previous month
• pregnant or breast-feeding women
• not willing to give up being a blood donor (or having donated blood) from 8 weeks before the start of the study and during the study
• current smoker
• anemia. with a Hb-level below 7.5 mmol/L for men and below 7.0 mmol/L for women, as indicated by the blood bank of Maastricht