Acute Dietary Nitrate Supplementation Improves Flow Mediated Dilatation of the Superficial Femoral Artery in Healthy Older Males.

Meegan A Walker,Christopher D Askew,Daniel J Green,Luke Mcilvenna,Tom G Bailey,Jason D Allen

doi:10.3390/nu11050954

Abstract

Aging is often associated with reduced leg blood flow, increased arterial stiffness, and endothelial dysfunction, all of which are related to declining nitric oxide (NO) bioavailability. Flow mediated dilatation (FMD) and passive leg movement (PLM) hyperaemia are two techniques used to measure NO-dependent vascular function. We hypothesised that acute dietary nitrate (NO3−) supplementation would improve NO bioavailability, leg FMD, and PLM hyperaemia. Fifteen healthy older men (69 ± 4 years) attended two experiment sessions and consumed either 140 mL of concentrated beetroot juice (800 mg NO3−) or placebo (NO3−-depleted beetroot juice) in a randomised, double blind, cross-over design study. Plasma nitrite (NO2−) and NO3−, blood pressure (BP), augmentation index (AIx75), pulse wave velocity (PWV), FMD of the superficial femoral artery, and PLM hyperaemia were measured immediately before and 2.5 h after consuming NO3− and placebo. Placebo had no effect but NO3− led to an 8.6-fold increase in plasma NO2−, which was accompanied by an increase in FMD (NO3−: +1.18 ± 0.94% vs. placebo: 0.23 ± 1.13%, p = 0.002), and a reduction in AIx75 (NO3−: −8.7 ± 11.6% vs. placebo: −4.6 ± 5.5%, p = 0.027). PLM hyperaemia, BP, and PWV were unchanged during both trials. This study showed that a dose of dietary NO3− improved NO bioavailability and enhanced endothelial function as measured by femoral artery FMD. These findings provide insight into the specific central and peripheral vascular responses to dietary NO3− supplementation in older adults.

Highlights

Cardiovascular diseases are the leading cause of morbidity and mortality worldwide [1] and there is considerable interest in strategies to promote healthy aging
Several factors contribute to the age-related decline in cardiovascular health, and a central determinant is the bioavailability of nitric oxide (NO)
The primary aim of this placebo-controlled, double-blind, cross-over design study was to determine whether NO3 − supplementation would improve vascular function in older adults

Summary

Introduction

Cardiovascular diseases are the leading cause of morbidity and mortality worldwide [1] and there is considerable interest in strategies to promote healthy aging. NO bioavailability [5], which contributes to age-related increases in blood pressure and vascular stiffness [6] and the associated risk of cardiovascular events [3,7]. Impairments in NO bioavailability may lead to a reduction in limb blood flow, possibly through the role of NO in functional sympatholysis [8] and endothelium-dependent vasodilation [9,10]. The decrease in blood flow is evident in the legs [11,12] and is associated with reduced muscle function and diminished exercise capacity. Strategies to improve NO bioavailability, and thereby improve vascular function and enhance leg blood flow, may help in the prevention and management of age-related cardiovascular impairments

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