One Week of Daily Dosing With Beetroot Juice Improves Submaximal Endurance and Blood Pressure in Older Patients With Heart Failure and Preserved Ejection Fraction

Abstract

Objectives: This study sought to determine whether a relatively low single dose or a week-long dosage of dietary inorganic nitrate could improve exercise tolerance in patients with heart failure with preserved ejection fraction (HFpEF).

Background: Exercise intolerance is the primary manifestation of HFpEF and is largely due to noncardiac factors that reduce oxygen delivery to active skeletal muscles. A recent study showed improved exercise capacity in patients with HFpEF after a single, acute dose of beetroot juice (BRJ) (12.9 mmol inorganic nitrate) while another recent study showed neutral and negative effects of an organic nitrate.

Methods: Twenty HFpEF patients (69 ± 7 years of age ) were enrolled in an initial cross-over design comparing a single, acute dose of BRJ (6.1 mmol nitrate) to a nitrate-depleted placebo BRJ. A second phase, 1 week of daily doses, used an all-treated design in which patients consumed BRJ for an average of 7 days. The primary outcome of the study was submaximal aerobic endurance, measured as cycling time to exhaustion at 75% of measured maximal power output.

Results: No adverse events were associated with the intervention. Submaximal aerobic endurance improved 24% after 1 week of daily BRJ dosing (p = 0.02) but was not affected by the single, acute dose of the BRJ compared to placebo. Consumption of BRJ significantly reduced resting systolic blood pressure and increased plasma nitrate and nitrite in both of the dosing schemes.

Conclusions: One week of daily dosing with BRJ (6.1 mmol inorganic nitrate) significantly improves submaximal aerobic endurance and blood pressure in elderly HFpEF patients.

Keywords: exercise; heart failure with preserved ejection fraction; nitrate; nitric oxide; nitrite.

Copyright © 2016 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1. Plasma nitrite and nitrate

Mean ± SE of plasma nitrite and plasma nitrate after a single, acute dose (panel A) and after 1-week of daily dosing (panel B). White columns represent placebo and black columns represent BRJ. **=p

Figure 2. Exercise Time

Submaximal exercise time (sec.) with placebo and single, acute dose of BRJ (panel A) and with placebo and 1-week of daily dosing of BRJ (panel B). Black squares represent mean values. Circles and lines represent individual values.

Figure 3. Oxygen Consumption and Blood Pressure

VO2 (ml/kg/min) and systolic blood pressure (mmHg) at rest, after unloaded cycling, after 2 and 4 minutes of cycling, and at volitional exhaustion with single, acute dosing (panel A) and with 1-week of daily dosing (panel B). The solid line represents placebo and the dotted line represents BRJ. **=p<0.001; *=p<0.05.