Oral nitrate supplementation improves cardiovascular risk markers in COPD: ON-BC a randomised controlled trial

Abstract

BACKGROUND: Short term studies suggest that dietary nitrate supplementation may improve cardiovascular risk profile, lowering blood pressure (BP) and enhancing endothelial function. It is not clear if these beneficial effects are sustained and whether they apply in people with COPD, who have a worse cardiovascular profile than those without COPD. Nitrate-rich beetroot juice BRJ (NR-BRJ) is a convenient dietary source of nitrate. METHODS: The ON-BC trial was a randomized, double-blind, placebo-controlled parallel group study in stable COPD patients with home systolic BP (SBP) measurement ≥130 mmHg. Participants were randomly allocated (1:1) using computer-generated, block randomization to either 70 mL of NR-BRJ (400 mg NO3 -) (n=40) or an otherwise identical nitrate-depleted placebo juice Pl-BRJ (0 mg NO3 -) (n=41), once daily for 12 weeks. The primary endpoint was between group change in home SBP measurement. Secondary outcomes included change in 6-minute walking distance (6MWD) and measures of endothelial function (reactive hyperaemia index (RHI) and augmentation index (AIx75)) using an EndoPAT device. Plasma nitrate and platelet function were also measured. RESULTS: Compared to placebo, active treatment lowered SBP (Hodges-Lemman treatment effect MD[95% CI]; -4.5[-3.0 to -5.9] improved 6MWD (+30.0 m [15.7 to 44.2], p<0.001), RHI +0.34 (0.03 to 0.63) p=0.03, and AIx75 -7.61% [-14.3 to -0.95], p=0.026. CONCLUSIONS: In people with COPD, prolonged dietary nitrate supplementation in the form of beetroot juice produces a sustained reduction in BP, associated with an improvement in endothelial function and exercise capacity.