SFAs do not impair endothelial function and arterial stiffness

Risck Study Group ,Thomas Ab Sanders,Fiona J Lewis,Louise M Goff,Philip J Chowienczyk

doi:10.3945/ajcn.113.063644

Abstract

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 monounsaturated fatty acids (MUFAs) or carbohydrates on endothelial function and arterial stiffness.Design: With the use of a parallel-designed randomized controlled trial in 121 insulin-resistant men and women, we measured vascular 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 carbohydrates. 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 F2α-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 ± 2.2%, and changes (95% CIs) after 6 mo of intervention were +0.3 (−0.4, 1.1), −0.2 (−0.8, 0.5), and −0.1 (−0.6, 0.7) with HS, high-MUFA (HM), and high-carbohydrate (HC) diets, respectively. After consumption of the HS reference diet, the geometric mean (±SD) PWV was 7.67 ± 1.62 m/s, and mean percentages of changes (95% CIs) were −1.0 (−6.2, 4.3) with the HS diet, 2.7 (−1.4, 6.9) with the HM diet, and −1.0 (−5.5, 3.4) with the HC diet. With the HS reference diet, the geometric mean (±SD) plasma 8-isoprostane F2α-III concentration was 176 ± 85 pmol/L, and mean percentage of changes (95% CIs) were 1 (−12, 14) with the HS diet, 6 (−5, 16) with the HM diet, and 4 (−7, 16) with the HC diet.Conclusion: The replacement of SFAs with MUFAs or carbohydrates in healthy subjects does not affect vascular function. This trial was registered at Current Controlled Trials (http://www.controlled-trials.com/ISRCTN) as ISRCTN 29111298.

Highlights

It has been well established that SFAs influence plasma lipid concentrations, but their effects on arterial function remain uncertain [1]
Compared with the HS reference diet, SFA intakes fell to,10% of energy, and the intake of monounsaturated fatty acids (MUFAs) was greater with the MUFA diet, and the intake of carbohydrates was greater with HC diets
The intake of PUFA margarine and g walnuts (PUFA) was lower with the HC than MUFA diet, but the size of the difference was small, and analyses of the plasma phospholipid composition showed no differences between treatments in proportions of PUFAs

Summary

Introduction

It has been well established that SFAs influence plasma lipid concentrations, but their effects on arterial function remain uncertain [1]. The plasma concentration of plasma 8-isoprostane F2a-III is regarded as a robust marker of increased free-radical oxidation, and we have previously shown that high-fat meals (50 g) compared with carbohydrates result in increased plasma concentrations of this metabolite [8, 9] and transiently impaired endothelial function [8, 10]. It is uncertain whether saturated fatty acids (SFAs) impair endothelial function and contribute to arterial stiffening.

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