Effects of Beetroot Powder with or without L-Arginine on Postprandial Vascular Endothelial Function: Results of a Randomized Controlled Trial with Abdominally Obese Men.

Ellen T H C Smeets,Johan De Vogel-Van Den Bosch,Peter J Joris,Joris Hoeks,Robert J J Hageman,Ronald P Mensink

doi:10.3390/nu12113520

Abstract

Background: Through effects on nitric oxide bioavailability, vascular endothelial function is improved after the intake of a high amount of nitrate or L-arginine, but decreased after the intake of a high-fat meal. Therefore, we compared the effects of beetroot powder with or without L-arginine on postprandial brachial artery flow-mediated vasodilation (FMD) after consumption of a high-fat mixed-meal. Methods: Eighteen abdominally obese men completed this randomized, double-blinded, cross-over trial. The study consisted of five test days, each separated by a wash-out period of at least one week. Participants received in random order, a blended meal with a control or nutritional supplement consisting of beetroot powder providing 200 mg nitrate, beetroot with 0.8 g of L-arginine, beetroot with 1.5 g of L-arginine, or 3.0 g of L-arginine. Participants then fasted and 2 h postprandial FMD measurements were performed. Results: No significant differences between meals were observed for postprandial FMD (p = 0.45) levels. However, there was a non-significant trend towards a more beneficial postprandial FMD response with the beetroot-containing meals as compared with meals without beetroot. Conclusion: This trial could not provide evidence for beneficial additive effects of a single dose of beetroot powder combined with L-arginine on postprandial endothelial function in abdominally obese men.

Highlights

Nitric oxide (NO) is a gas that contributes to the maintenance of a healthy endothelial function, as it prevents long-term atherosclerotic disease progression and cardiovascular event rates because it exerts important vasodilatory, anti-inflammatory, antithrombotic, anti-proliferative, and anti-adhesive effects [1,2,3]
One participant was excluded from all statistical analyses due to a chronic disease that was not reported during the screening visit but became evident by high plasma hsCRP values during all test days (i.e., 10–57 mg/L)
Double-blinded, cross-over study with healthy, abdominally obese men, nutritional supplements containing beetroot and/or various amounts of L-arginine powder did not differently affect postprandial flow-mediated vasodilation (FMD) when consumed with a high-fat mixed-meal

Summary

Introduction

Nitric oxide (NO) is a gas that contributes to the maintenance of a healthy endothelial function, as it prevents long-term atherosclerotic disease progression and cardiovascular event rates because it exerts important vasodilatory, anti-inflammatory, antithrombotic, anti-proliferative, and anti-adhesive effects [1,2,3]. A high-fat meal may lower NO bioavailability, resulting in an impaired postprandial FMD [6]. Our group has shown that consumption of beetroot juice providing about 500 mg of nitrate improves postprandial FMD two hours after consumption of a high-fat meal challenge in overweight and slightly obese men [8]. The results of our recent meta-analysis of randomized controlled trials suggest that high-dose L-arginine supplementation improves postprandial FMD in humans [10]. Through effects on nitric oxide bioavailability, vascular endothelial function is improved after the intake of a high amount of nitrate or L-arginine, but decreased after the intake of a high-fat meal. We compared the effects of beetroot powder with or without L-arginine on postprandial brachial artery flow-mediated vasodilation (FMD) after consumption of a high-fat mixed-meal.

Methods

Results

Conclusion