Effect of fat-reformulated dairy food consumption on postprandial flow-mediated dilatation and cardiometabolic risk biomarkers compared with conventional dairy: a randomized controlled trial

Background: Longer-term consumption of saturated fatty acid (SFA)-reduced, monounsaturated fatty acid (MUFA)-enriched dairy products have been reported to improve fasting flow-mediated vasodilation (FMD). Yet, their impact on endothelial function in the postprandial state warrants investigation.
Objective: To compare the impact of a fatty acid (FA)-modified with a conventional (control) dairy diet on the postprandial %FMD (primary outcome) and systemic cardiometabolic responses to representative meals, and retrospectively explore whether treatment effects differ by apolipoprotein (APO)E or endothelial nitric oxide synthase (eNOS) Glu298Asp gene polymorphisms.
Methods: In a crossover-design randomized controlled study, 52 adults with moderate cardiovascular disease risk consumed dairy products [38% total energy intake (%TE) from fat: FA-modified (target: 16%TE SFAs; 14%TE MUFAs) or control (19%TE SFAs; 11%TE MUFAs)] for 12-wk, separated by an 8-wk washout. Blood sampling and FMD measurements (0-480 min) were performed pre- and post-intervention after sequential mixed meals that were representative of the assigned dairy diets (0 min; ~50 g fat; 330 min; ~30 g fat).
Results: Relative to pre-intervention (∆), the FA-modified dairy diet and meals (treatment) attenuated the increase in the incremental AUC (iAUC), but not AUC, for the %FMD response observed with the conventional treatment (-135 ± 69 vs +199 ± 82 % x min; P = 0.005). The ∆ iAUC, but not AUC, for the apoB response decreased after FA-modified yet increased after the conventional treatment (-4 ± 3 vs +3 ± 3 mg/mL x min; P = 0.004). The ∆ iAUC decreased for total plasma SFAs (P = 0.003) and trans 18:1 (P < 0.0001) and increased for cis-MUFAs (P < 0.0001) following conventional, relative to the FA-modified treatment. No treatment x APOE- or eNOS-genotype interactions were evident for any outcome.
Conclusions: This study provides novel insights into the longer-term effects of FA-modified dairy food consumption on postprandial cardiometabolic responses. This study was registered at clinicaltrials.gov as NCT02089035.