National Heart and Lung Institute, Imperial College London, London, UK.
Clinical and Experimental Sciences, Southampton Hospital, Southampton, UK.
Thorax. 2022 Oct;77(10):968-975. doi: 10.1136/thoraxjnl-2021-217147. Epub 2021 Dec 1.
Dietary nitrate supplementation improves skeletal muscle oxygen utilisation and vascular endothelial function. We hypothesised that these effects might be sufficient to improve exercise performance in patients with COPD and hypoxia severe enough to require supplemental oxygen.
We conducted a single-centre, double-blind, placebo-controlled, cross-over study, enrolling adults with COPD who were established users of long-term oxygen therapy. Participants performed an endurance shuttle walk test, using their prescribed oxygen, 3 hours after consuming either 140 mL of nitrate-rich beetroot juice (BRJ) (12.9 mmol nitrate) or placebo (nitrate-depleted BRJ). Treatment order was allocated (1:1) by computer-generated block randomisation.
The primary outcome was endurance shuttle walk test time. The secondary outcomes included area under the curve to isotime for fingertip oxygen saturation and heart rate parameters during the test, blood pressure, and endothelial function assessed using flow-mediated dilatation. Plasma nitrate and nitrite levels as well as FE were also measured.
20 participants were recruited and all completed the study. Nitrate-rich BRJ supplementation prolonged exercise endurance time in all participants as compared with placebo: median (IQR) 194.6 (147.5-411.7) s vs 159.1 (121.9-298.5) s, estimated treatment effect 62 (33-106) s (p<0.0001). Supplementation also improved endothelial function: NR-BRJ group +4.1% (-1.1% to 14.8%) vs placebo BRJ group -5.0% (-10.6% to -0.6%) (p=0.0003).
Acute dietary nitrate supplementation increases exercise endurance in patients with COPD who require supplemental oxygen. ISRCTN14888729.
饮食硝酸盐补充可改善骨骼肌氧利用和血管内皮功能。我们假设这些作用足以改善患有 COPD 且缺氧严重需要补充氧气的患者的运动表现。
我们进行了一项单中心、双盲、安慰剂对照、交叉研究，纳入了长期接受氧疗的 COPD 成年患者。参与者在服用富含硝酸盐的甜菜根汁（BRJ）（12.9mmol 硝酸盐）或安慰剂（硝酸盐耗尽的 BRJ）后 3 小时，使用规定的氧气进行耐力穿梭步行测试。治疗顺序通过计算机生成的区块随机化分配（1:1）。
主要结果是耐力穿梭步行测试时间。次要结果包括测试期间指尖血氧饱和度和心率参数的曲线下面积到等时、血压以及使用血流介导的扩张评估的内皮功能。还测量了血浆硝酸盐和亚硝酸盐水平以及 FEV1。
共招募了 20 名参与者，所有人都完成了研究。与安慰剂相比，富含硝酸盐的 BRJ 补充剂延长了所有参与者的运动耐力时间：中位数（IQR）194.6（147.5-411.7）s 与 159.1（121.9-298.5）s，估计治疗效果为 62（33-106）s（p<0.0001）。补充剂还改善了内皮功能：NR-BRJ 组+4.1%（-1.1%至 14.8%）与安慰剂 BRJ 组-5.0%（-10.6%至-0.6%）（p=0.0003）。
急性饮食硝酸盐补充可增加需要补充氧气的 COPD 患者的运动耐力。ISRCTN83235729。
