Vascular function decreases following the intake of a mixed meal in some, but not all studies. Differences in the relative amounts of dietary fat, carbohydrates and protein present in the mixed-meal challenges may have contributed to these apparently inconsistent results. Well-designed trials - comparing under rigorously standardized conditions - on the effects of macronutrients on postprandial vascular function are missing. The primary objective of the current study is thus to evaluate in overweight and slightly obese men the effects of the three macronutrients (fat, carbohydrates, and protein) on postprandial vascular function, as assessed by brachial artery flow-mediated vasodilation (FMD). Secondary objectives are to examine postprandial effects on other markers reflecting vascular function, plasma markers for low-grade systemic inflammation and endothelial dysfunction, blood pressure, and serum lipid and plasma glucose metabolism.

Inclusion Criteria:

• Aged between 18-70 years
• Men
• BMI between 25-35 kg/m2 (overweight and slightly obese)
• Fasting plasma glucose < 7.0 mmol/L
• Fasting serum total cholesterol < 8.0 mmol/L
• Fasting serum triacylglycerol < 2.2 mmol/L
• Systolic blood pressure < 160 mmHg and diastolic blood pressure < 100 mmHg
• No current smoker
• No diabetic patients
• No familial hypercholesterolemia
• No abuse of drugs
• No more than 3 alcoholic consumptions per day
• Stable body weight (weight gain or loss < 3 kg in the past three months)
• No use of dietary supplements known to interfere with the main study outcomes as judged by the principal investigator
• No use of medication to treat blood pressure, lipid or glucose metabolism
• No use of an investigational product within another biomedical intervention trial within the previous 1-month
• No severe medical conditions that might interfere with the study, such as epilepsy, asthma, kidney failure or renal insufficiency, chronic obstructive pulmonary disease, inflammatory bowel diseases, auto inflammatory diseases and rheumatoid arthritis
• No active cardiovascular disease like congestive heart failure or cardiovascular event, such as an acute myocardial infarction or cerebrovascular accident
• Willingness to give up being a blood donor from 8 weeks before the start of the study, during the study and for 4 weeks after completion of the study
• No difficult venipuncture as evidenced during the screening visit

Exclusion Criteria:

• Women
• Fasting plasma glucose ≥ 7.0 mmol/L
• Fasting serum total cholesterol ≥ 8.0 mmol/L
• Fasting serum triacylglycerol ≥ 2.2 mmol/L
• Systolic blood pressure ≥ 160 mmHg and/or diastolic blood pressure ≥ 100 mmHg
• Current smoker, or smoking cessation < 12 months
• Diabetic patients
• Familial hypercholesterolemia
• Abuse of drugs
• More than 3 alcoholic consumptions per day
• Unstable body weight (weight gain or loss > 3 kg in the past three months)
• Use of dietary supplements known to interfere with the main study outcomes as judged by the principal investigator
• Use medication to treat blood pressure, lipid or glucose metabolism
• Use of an investigational product within another biomedical intervention trial within the previous 1-month
• Severe medical conditions that might interfere with the study, such as epilepsy, asthma, kidney failure or renal insufficiency, chronic obstructive pulmonary disease, inflammatory bowel diseases, auto inflammatory diseases and rheumatoid arthritis
• Active cardiovascular disease like congestive heart failure or cardiovascular event, such as an acute myocardial infarction or cerebrovascular accident
• Not willing to give up being a blood donor from 8 weeks before the start of the study, during the study or for 4 weeks after completion of the study
• Not or difficult to venipuncture as evidenced during the screening visit