SFAs do not impair endothelial function and arterial stiffness1–3

Background: It is uncertain whether saturated fatty acids (SFAs) impair endothelial function and contribute to arterial stiffening. Objective: We tested the effects of replacing SFAs with monoun-saturated fatty acids (MUFAs) or carbohydrates on endothelial func-tion and arterial stiffness. Design: With the use of a parallel-designed randomized controlled trial in 121 insulin-resistant men and women, we measured vascu-lar function after 1 mo of consumption of a high-SFA (HS) diet and after 24 wk after random assignment to the HS diet or diets that contained,10 % SFAs and were high in either MUFAs or carbo-hydrates. The primary outcome was a change in flow-mediated dilation (FMD), and secondary outcomes were changes in carotid to femoral pulse wave velocity (PWV) and plasma 8-isoprostane F2a-III concentrations. Results: For 112 participants with data available for analysis on the specified outcomes, no significant differences were shown. FMD with the HS reference diet was 6.7 6 2.2%, and changes (95% CIs) after 6 mo of intervention were +0.3 (20.4, 1.1), 20.2 (20.8, 0.5), and 20.1 (20.6, 0.7) with HS, high-MUFA (HM), and high-carbohydrate (HC) diets, respectively. After consumption of the HS reference diet, the geometric mean (6SD) PWVwas 7.676 1.62 m/s, and mean percentages of changes (95 % CIs) were 21.0 (26.2, 4.3) with the HS diet, 2.7 (21.4, 6.9) with the HM diet, and 21.0 (25.5, 3.4) with the HC diet. With the HS reference diet, the geometric mean (6SD) plasma 8-isoprostane F2a-III concentration was 176 6 85 pmol/L, and mean percentage of changes (95 % CIs) were 1 (212, 14) with the HS diet, 6 (25, 16) with the HM diet, and 4 (27, 16) with the HC diet. Conclusion: The replacement of SFAs with MUFAs or carbohydrates in healthy subjects does not affect vascular function. This trial wa