Acute Dietary Nitrate Supplementation and Exercise Performance in COPD: A Double-Blind, Placebo-Controlled, Randomised Controlled Pilot Study

Double-blind, placebo-controlled, randomised controlled pilot study in adults with COPD, including GOLD stage II-IV disease, recruited from outpatient settings and not receiving long-term oxygen therapy. In the nitrate-rich beetroot juice arm, 21 participants completed the study.

A single oral dose of 140 mL nitrate-rich BEET-IT Sport Stamina Shot containing 0.8 g nitrate (12.9 mmoles nitrate) was given 3 hours before endurance cycle ergometry. The comparator was 140 mL nitrate-depleted beetroot juice.

Acute nitrate supplementation did not improve endurance cycling time at 70% maximum workload, but it produced measurable physiological effects. Endurance time was 5.65 (3.90-10.40) minutes with nitrate versus 6.40 (4.01-9.67) minutes with placebo (p = 0.50). Isotime VO2 was lower after nitrate, 16.6 (6.0) versus 17.2 (6.0) ml/min/kg (p = 0.043), and resting diastolic blood pressure fell more, -7±8 mmHg versus -1±8 mmHg (p = 0.008). Plasma nitrate increased from 37.0 ± 16.4 μM at baseline to 820.2 ± 187.7 μM post-dose and 917.1 ± 291.6 μM at peak exercise (p < 0.0001); no adverse effects were noted except beeturia. The authors concluded the intervention was safe and inexpensive, but further work is needed to identify COPD phenotypes that may benefit.

This was a small pilot study with only 21 completers in the active arm, limiting power to detect performance effects. The intervention was acute and short-term, so it does not address sustained efficacy or longer-term safety. Findings are specific to a COPD outpatient population and may not generalize to other phenotypes or more severe disease.