The primary aim of this study is to evaluate the effect of a high fat challenge on several measures of endothelial function. The secondary aim of this study is to elucidate the mechanism of postprandial endothelial dysfunction and to identify early biomarkers

Endothelial dysfunction (ED) is a hallmark for the initial stage of vascular dysfunction and has been associated with diet-related disorders such as cardiovascular disease. This makes prevention of ED an important health target. From previous studies we know that a high-fat (HF) meal (challenge) impairs postprandial endothelial function (EF). Current studies only evaluated the effect of a HF meal on Flow Mediated Dilatation (FMD), a measure of macro vascular EF. This methodology (FMD) however, is time consuming and large variations in reproducibility are reported in literature. The question remains whether other types of macro- and micro vascular EF measurements can be used to observe ED after a HF meal that are more accurate, faster and easier to perform. In addition, it is know that the postprandial phase results in activation of leukocytes. This activation of leukocytes is likely to contribute to ED, but the exact underling mechanism remains unclear.

Inclusion Criteria:

• male, caucasian

Exclusion Criteria: • Allergic to cow milk or dairy products

• Body mass index (BMI) < 18 or > 25 kg/m2
• Urine glucose concentrations outside normal ranges (>0,25 g/l)
• Fasting blood glucose outside the normal range (3 - 5.5 mmol/L)
• Tobacco smoking
• Taking medication or food supplements.
• Received inoculations within 2 months of starting the study or planned to during the study
• Donated or intended to donate blood from 2 months before the study till two months after the study
• Blood Hb values below 8.4 mmol/L
• Diagnosed with any long-term medical condition (e.g., diabetes, hemophilia, cardiovascular disease, anemia, gastrointestinal disease, renal failure)
• High blood pressure (systolic BP> 140 mmHg and/or diastolic BP>90 mmHg)