Effects of n-3 fatty acids on macro- and microvascular function in subjects with type 2 diabetes mellitus

Abstract

Background: Recent evidence supports the protective effects of n - 3 (omega-3) fatty acids (n - 3 FAs), such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), on vascular function. Objective: We investigated the effects of EPA and DHA on post-prandial vascular function in subjects with type 2 diabetes mellitus. Design: In a double-blind, placebo-controlled, randomized, crossover manner, 34 subjects with type 2 diabetes mellitus received daily either 2 g purified EPA/DHA (termed n - 3 FAs) or olive oil (placebo) for 6 wk. At the end of this period, we measured macrovascular (brachial ultrasound of flow-mediated dilatation; FMD) and microvascular [laser-Doppler measurements of reactive hyperemia (RH) of the hand] function at fasting and 2, 4, and 6 h after a highfat meal (600 kcal, 21 g protein, 41 g carbohydrates, 40 g fat). Results: Fasting vascular function remained unchanged after n - 3 FAs and placebo. Postprandial FMD decreased from fasting after placebo, with a maximum decrease (38%) at 4 h - an effect that was significantly reduced (P = 0.03 for time • treatment interaction) by n - 3 FA supplementation (maximum decrease in FMD was at 4 h: 13%). RH remained unchanged after placebo, whereas it improved significantly (P = 0.04 for time • treatment interaction) after n - 3 FA supplementation (maximum increase was at 2 h: 27%). Conclusions: In subjects with type 2 diabetes mellitus, 6 wk of supplementation with n - 3 FAs reduced the postprandial decrease in macrovascular function relative to placebo. Moreover, n - 3 FA supplementation improved postprandial microvascular function. These observations suggest a protective vascular effect of n - 3 FAs. © 2010 American Society for Nutrition.