Dietary Nitrate Increases VO2peak and Performance but Does Not Alter Ventilation or Efficiency in Patients With Heart Failure With Reduced Ejection Fraction

Abstract

Background: Patients with heart failure with reduced ejection fraction (HFrEF) exhibit lower efficiency, dyspnea, and diminished peak oxygen uptake (VO2peak) during exercise. Dietary nitrate (NO3-), a source of nitric oxide (NO), has improved these measures in some studies of other populations. We determined the effects of acute NO3- ingestion on exercise responses in 8 patients with HFrEF using a randomized, double-blind, placebo-controlled, crossover design.

Methods and results: Plasma NO3-, nitrite (NO2-), and breath NO were measured at multiple time points and respiratory gas exchange was determined during exercise after ingestion of beetroot juice containing or devoid of 11.2 mmol of NO3-. NO3- intake increased (P < .05-0.001) plasma NO3- and NO2- and breath NO by 1469 ± 245%, 105 ± 34%, and 60 ± 18%, respectively. Efficiency and ventilation during exercise were unchanged. However, NO3- ingestion increased (P < .05) VO2peak by 8 ± 2% (ie, from 21.4 ± 2.1 to 23.0 ± 2.3 mL.min-1.kg-1). Time to fatigue improved (P < .05) by 7 ± 3 % (ie, from 582 ± 84 to 612 ± 81 seconds).

Conclusions: Acute dietary NO3- intake increases VO2peak and performance in patients with HFrEF. These data, in conjunction with our recent data demonstrating that dietary NO3- also improves muscle contractile function, suggest that dietary NO3- supplementation may be a valuable means of enhancing exercise capacity in this population.

Keywords: Nitric oxide; VO(2)peak; exercise; heart failure.

Copyright © 2017 Elsevier Inc. All rights reserved.

Figures

Figure 1

CONSORT diagram illustrating flow of subjects through the study.

Figure 2

Experimental design (top panel) and protocol (bottom panel).

Figure 3

Effect of acute ingestion of beetroot juice either devoid of (Placebo; open bars) or containing (Nitrate; solid bars) 11.2 mmol of NO3- on plasma NO3- (top panel) and NO2- (middle panel) concentrations and breath NO levels (bottom panel) in patients with heart failure with reduced ejection fraction. Values are mean ± SE for n=8. 10′ Post = 10 min post-exercise. Nitrate significantly higher than than Placebo at same time point: *P<0.05, †P<0.01, ‡P<0.001.

Figure 4

Effect of acute ingestion of beetroot juice either devoid of (Placebo; open bar or symbols) or containing (Nitrate; solid bar or symbols) 11.2 mmol of NO3- on time to fatigue (top panel) and peak O2 consumption (VO2peak; bottom panel) during an incremental exercise test in patients with heart failure with reduced ejection fraction. Values are mean ± SE for n=8; individual results are also shown (circles, men; squares, women). *Nitrate significantly higher than Placebo: P<0.05.