A double blind randomized placebo control crossover trial on the effect of dietary nitrate supplementation on exercise tolerance in stable moderate chronic obstructive pulmonary disease

Study answer

What this study found

BR nitrate did not significantly improve endurance: ESWT distance increased by 11% (79 m) but p = 0.494; ESWT time to fatigue increased by 0.6 minutes (6%) but p = 0.693. Distances were 721.6 ± 587.5 m on placebo vs 800.0 ± 584.3 m on BR. Safety: resting systolic BP decreased by ~10 mmHg at 1 hour; one participant developed symptomatic postural hypotension and was excluded; diastolic BP and dyspnea scores showed no significant changes. Conclusion: Routine acute dietary nitrate supplementation with BR is not supported to enhance submaximal exercise endurance in moderate COPD; observed…

Study & population

Design: double-blind, computer-randomized, placebo-controlled crossover trial at a tertiary Australian hospital.

Intervention

Beetroot juice containing nitrate; 70 mL per dose delivering 4.8 mmol NO3−; taken orally twice daily for three days prior to endurance shuttle walk testing, with a final dose on the morning of testing.

Key limitation

High attrition (35 enrolled; 19 completed); no biochemical verification of nitrate/nitrite levels; no plasma measures to confirm exposure or kinetics; relatively small sample with large variability; potential carryover effects in a crossover design; limited generalizability to COPD phenotypes beyond GOLD II;…

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Original abstract