Abstract/Summary

Background: Elevated postprandial triacylglycerol concentrations, impaired vascular function and hypertension are important independent cardiovascular disease (CVD) risk factors in women. However, the effects of meal fat composition on postprandial lipemia and vascular function in postmenopausal women are unknown. Objective: This study investigated the impact of sequential meals rich in saturated (SFAs), monounsaturated (MUFAs) or n-6 polyunsaturated fatty acids (PUFAs) on postprandial flow-mediated dilatation (FMD, primary outcome measure), vascular function and associated CVD risk biomarkers (secondary outcomes) in postmenopausal women. Methods: A double-blind, randomized, cross-over, postprandial study was conducted with 32 postmenopausal women (58 ± 1 years, BMI 25.9 ± 0.7 kg/m2). After fasting overnight, participants consumed high-fat meals at breakfast (0 min; 50 g fat, containing 33-36 g SFAs, MUFAs or n-6 PUFAs) and lunch (330 min; 30 g fat, containing 19-20 g SFAs, MUFAs or n-6 PUFAs), on separate occasions. Blood samples were collected before breakfast and regularly after the meals for 480 min, with specific time points selected for measuring vascular function and blood pressure. Results: Postprandial FMD, laser Doppler imaging and digital volume pulse responses were not different after consuming the test fats. The incremental AUC (IAUC) for diastolic blood pressure was lower (-0.5-fold) after the MUFA than SFA-rich meals (P=0.009), with a similar trend for systolic blood pressure (-0.4-fold; P=0.012). This corresponded with a lower IAUC (-6.4-fold) for the plasma nitrite response after the SFA than MUFA-rich meals (P=0.010). The soluble intercellular adhesion molecule-1 (sICAM-1) time course profile, AUC and IAUC were lower after the n-6 PUFA than SFA and MUFA-rich meals (P≤0.001). Lipids, glucose and markers of insulin sensitivity did not differ between the test fats. Conclusions: Our study revealed a differential impact of meal fat composition on blood pressure, plasma nitrite and sICAM-1, but no effect on postprandial FMD or lipemia in postmenopausal women.