Dietary nitrate supplementation and exercise tolerance in patients with heart failure with reduced ejection fraction.

American journal of physiology. Regulatory, integrative and comparative physiology
Citations:49
Influential Citations:3
Interventional (Human) Studies
83
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Methods
Double-blind, randomized crossover design. Ten male participants with heart failure with reduced ejection fraction (LVEF ~32%, NYHA II-III; ischemic heart disease 8, dilated cardiomyopathy 2). Age 63 ± 5 years. Stable medical therapy. Recruited from outpatient Heart Failure Clinic; 13 screened, 10 completed.
Intervention
Beetroot juice regimen: two 70-ml bottles daily for 9 consecutive days; nitrate-rich juice contained approximately 6.45 mmol nitrate per bottle; morning bottle consumed ~2 hours before testing and the afternoon bottle later in the day; placebo beverage was nitrate-depleted beetroot juice; bottles identical in packaging.
Results
Plasma nitrite concentration increased with nitrate-rich supplementation to about 240 ± 48 nM vs 56 ± 8 nM with placebo (P ≤ 0.05). Time to exercise intolerance did not differ significantly (placebo 495 ± 53 s vs nitrate 489 ± 58 s; P > 0.05). No significant differences were observed in arterial blood pressure, central hemodynamics (stroke volume, heart rate, cardiac output), pulmonary O2 uptake kinetics, skeletal muscle oxygenation, or blood lactate during rest-to-low- and rest-to-high-intensity transitions. Dietary nitrate via beetroot juice did not improve cardiorespiratory function or exercise tolerance in moderately impaired HFrEF; elevated plasma nitrite confirms uptake but did not translate to functional benefits. Further research is needed to identify subgroups, dosing, or duration that might yield benefits.
Limitations
Small, all-male sample (n=10) at a single center; short duration per arm (9 days); crossover design with potential carryover despite washout; limited generalizability to women or more severe disease; results may not apply to HF with preserved ejection fraction or non-ischemic etiologies.

Abstract

Endothelial dysfunction and reduced nitric oxide (NO) signaling are key abnormalities leading to skeletal muscle oxygen delivery-utilization mismatch and poor physical capacity in patients with heart failure with reduced ejection fraction (HFrEF). Or...