Dietary Macronutrients Do Not Differently Affect Postprandial Vascular Endothelial Function in Apparently Healthy Overweight and Slightly Obese Men

Well-designed trials comparing side-by-side effects of macronutrients on postprandial endothelial function are missing. Therefore, we investigated under well-controlled and isocaloric condition effects of fat, carbohydrates, and protein on postprandial endothelial function as assessed by brachial artery flow-mediated vasodilation (FMD), an important non-invasive technique to assess endothelial function. Eighteen apparently healthy overweight and slightly obese men (BMI 26.0–35.0 kg/m2) completed this randomized, double-blinded, cross-over trial. The study consisted of three test days each separated by a wash-out period of at least 1 week. After an overnight fast, men received an isocaloric meal providing 3987 kJ (953 kcal) that was either high in dietary fat (En% fat [F]/carbohydrates [C]/protein [P]: 52.3, 39.2, 8.0), carbohydrates (En% F/C/P: 9.6, 81.5, 8.6), or protein (En% F/C/P: 10.6, 51.5, 36.9). Fasting and 2-h postprandial FMD responses were measured. A postprandial decrease of 1.2% point in FMD was observed after the high-protein meal (P = 0.015). However, postprandial changes did not differ between meals (P = 0.45). An increase in baseline brachial artery diameters was observed after the high-protein meal (P < 0.001) and changes differed between meals (P = 0.020). A meal*time interaction was found for plasma glucose concentrations, with the most pronounced increases after the high-carbohydrate meal at T15, T30, T60, and T90 (P < 0.05). A significant time and meal (P < 0.001), but no time*meal effect (P = 0.06) was found for serum insulin concentrations. Increases in serum triacylglycerol concentrations did not differ between meals (P = 0.014). Macronutrients did not differently affect postprandial endothelial function in apparently healthy overweight and slightly obese men. Trial registration number (ClinicalTrials.gov) NCT03139890 in May 2017