Endothelial dysfunction, combined with inflammation, plays a significant role in the development of atherosclerosis and risk of cardiovascular disease (CVD)⁽ Reference Libby ^{1 )}. Reduction in dietary saturated fatty acid (SFA) intake is a key dietary recommendation for CVD risk reduction⁽ Reference Astrup, Dyerberg and Elwood ^{2 )}. However, it remains unclear whether monounsaturated fatty acids (MUFA) or n-6 polyunsaturated fatty acids (n-6 PUFA) are the optimal fatty acids to replace dietary SFA. The aim of this study was to determine the effects of substitution of SFA with either MUFA or n-6 PUFA on circulating markers of endothelial function and inflammation in men and women at increased risk of developing CVD.

A total of 195 men and women at increased CVD risk (mean age 44 (sd 10) years and BMI 26.9 ( sd 4.0) kg/m²) participated in a 16-week, parallel, randomised, controlled, single-blinded intervention study (DIVAS – (Dietary Intervention and VAscular function Study; ClinicalTrials.gov NCT01478958). Participants were randomly assigned (minimised for gender, age, BMI and CVD risk score) to one of the following isoenergetic diets: SFA-rich (target composition: 36% of total energy (%E) as total fat, 17%E SFA, 11%E MUFA, 4%E n-6 PUFA), MUFA-rich (36% E total fat, 9%E SFA, 19%E MUFA, 4%E n-6 PUFA), or n-6 PUFA-rich (36% E total fat, 9%E SFA, 13%E MUFA, 10%E n-6 PUFA). A flexible dietary model was developed to deliver the dietary interventions in which exchangeable fats in the habitual diet were replaced by study foods (spreads, oils, snacks) with a specific fatty acid composition. Vascular cell adhesion molecule-1 (VCAM-1), intracellular cell adhesion molecule-1 (ICAM-1), interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), E-Selectin, P-Selectin, von Willebrand factor (vWf) and C-Reactive protein (CRP) were determined by immunoassays in the fasting blood samples collected at baseline and following 16 weeks of intervention.

Blood E-Selectin levels (P=0.025) were significantly influenced by dietary fat composition. It was observed that there was a differential response after the MUFA-rich compared with the SFA-rich diet in which E-Selectin levels decreased after MUFA (Week16–Week0: −2.33 (sem 0.91) ng/ml) compared to the increase following the SFA-rich diet (Week16–Week0: 1.27 ( sem 1.01) ng/ml), (P=0.008). There were no significant effects of treatment on blood VCAM-1, ICAM-1, IL-6, TNF-α, P-Selectin, vWf and CRP.

In conclusion, this study suggests that replacement of dietary SFA with MUFA may have beneficial effects on circulating levels of E-Selectin.