Postprandial fatty acid profile, but not cardiometabolic risk markers, is modulated by dairy fat manipulation in adults with moderate cardiovascular disease risk: the randomized controlled REplacement of SaturatEd fat in dairy on Total cholesterol (RESET) study

Background: Chronic consumption of dairy products with a saturated fatty acid (SFA)- reduced, monounsaturated fatty acid (MUFA)-enriched content was shown to impact favourably on brachial artery flow-mediated dilatation (FMD). However, their acute effect on postprandial cardiometabolic risk biomarkers requires investigation.
Objective: The effects of sequential high-fat mixed meals rich in fatty acid (FA)-modified or conventional (control) dairy products on postprandial FMD (primary outcome) and systemic cardiometabolic biomarkers in adults with moderate cardiovascular risk (≥50% above population mean) were compared.
Methods: In a randomized cross-over trial, fifty-two participants (mean ± SEM age 53 ± 2 y; BMI 25.9 ± 0.5 kg/m2 ) consumed high-dairy fat breakfast (0 min; ~50 g total fat: Modified: 25 g SFAs, 20 g MUFAs; Control: 32 g SFAs, 12 g MUFAs) and lunch (330 min; ~30 g total fat; Modified: 15 g SFAs, 12 g MUFAs; Control: 19 g SFAs, 7 g MUFAs). Blood samples were obtained before and until 480 min after breakfast, with FMD assessed at 0, 180, 300 and 420 min. Data were analysed by linear mixed models.
Results: Postprandial changes in cardiometabolic biomarkers were comparable between the different dairy meals, with the exception of a tendency for a 4% higher area under the curve (AUC) for the %FMD response following the modified dairy fat meals (P = 0.075). Plasma total lipid FA analysis revealed that incremental AUC responses were 53% lower for total SFAs, 214% and 258% higher for total cis-MUFAs (predominantly cis-9 18:1), and trans 18:1 respectively following the modified, relative to control dairy meals (all P < 0.0001).
Conclusions: In adults at moderate cardiovascular risk, acute consumption of sequential high fat meals containing FA-modified dairy products had little impact on postprandial endothelial function or systemic cardiometabolic biomarkers, but a differential effect on the plasma total lipid FA profile, relative to conventional dairy fat meals.