Oral nitrate supplementation to enhance pulmonary rehabilitation in COPD: ON-EPIC a multicentre, double-blind, placebo-controlled, randomised parallel group study.
Level 2 - randomized trial
Multicentre, double-blind, placebo-controlled randomised trial.
PubMed 32376732 · doi:10.1136/thoraxjnl-2019-214278
What was done
A multicentre, double-blind, placebo-controlled randomised trial at four UK centres evaluated adults with GOLD grade II–IV COPD and MRC dyspnoea score 3–5 or functional limitation enrolled in an 8-week, twice-weekly pulmonary rehabilitation (PR) programme. 165 participants were randomised (1:1) to consume either 140 mL of nitrate-rich beetroot juice (12.9 mmol nitrate) or nitrate-deplete placebo beetroot juice 3 hours prior to each PR session. The primary outcome was the change in incremental shuttle walk test (ISWT) distance. Secondary outcomes included quality of life, physical activity, endothelial function via flow-mediated dilatation, fat-free mass index, and blood pressure.
What was found
165 participants were recruited and randomised (78 active, 87 placebo); primary outcome data were analysed for 57 active and 65 placebo participants. Active nitrate supplementation significantly improved ISWT distance compared to placebo: median (IQR) change +60 m (10, 85) versus +30 m (0, 70), estimated treatment effect 30 m (95% CI 10 to 40; p = 0.027). Active treatment also lowered systolic blood pressure: median change -5.0 mm Hg (-5.0, -3.0) versus control +6.0 mm Hg (-1.0, 15.5), estimated treatment effect -7 mm Hg (p < 0.0005). No significant serious adverse events were reported. Numeric values for quality of life, physical activity, endothelial function, and fat-free mass were not reported in the abstract.
Why it matters
Pre-exercise dietary nitrate supplementation appears to be an effective, non-pharmacological adjunct to pulmonary rehabilitation that enhances functional exercise capacity and blood pressure control in COPD.
Limits
There was notable attrition between randomisation (n = 165) and completion (n = 122 analysed). Findings for multiple secondary outcomes (e.g., quality of life, physical activity, endothelial function) lacked quantitative reporting in the abstract, and long-term maintenance of benefit was not assessed.
Cited by
- contradicts Gastrointestinal distress is a well-documented side effect of beetroot and citrulline supplementation.