BMJ Open Respir Res 2021 Sep;8(1):e000948. Impact of dietary nitrate supplementation on exercise capacity and cardiovascular parameters in chronic respiratory disease: a systematic review and meta-analysis Abdullah S Alsulayyim 1 2, Ali M Alasmari 1 3, Saeed M Alghamdi 1 4, Michael I Polkey 1, Nicholas S Hopkinson 5
1 National Heart and Lung Institute, Imperial College London, London, UK.
2 Faculty of Applied Medical Sciences, Respiratory Therapy Department, Jazan University, Jazan, Saudi Arabia.
3 Faculty of Medical Rehabilitation Sciences, Taibah University, Madinah, Saudi Arabia.
4 Clinical Technology Department, Umm Al-Qura University, College of Applied Medical Science, Makkah, Saudi Arabia.
5 National Heart and Lung Institute, Imperial College London, London, UK email@example.com.
Abstract Background: Dietary nitrate supplementation, usually in the form of beetroot juice, may improve exercise performance and endothelial function. We undertook a systematic review and meta-analysis to establish whether this approach has beneficial effects in people with respiratory disease. Methods: A systematic search of records up to March 2021 was performed on PubMed, CINAHL, MEDLINE (Ovid), Cochrane and Embase to retrieve clinical trials that evaluated the efficacy of dietary nitrate supplementation on cardiovascular parameters and exercise capacity in chronic respiratory conditions. Two authors independently screened titles, abstracts and full texts of potential studies and performed the data extraction. Results: After full-text review of 67 papers, eleven (two randomised controlled trials and nine crossover trials) involving 282 participants met the inclusion criteria. Three were single dose; seven short term; and one, the largest (n=122), done in the context of pulmonary rehabilitation. Pooled analysis showed that dietary nitrate supplementation reduced systolic blood pressure (BP), diastolic BP and mean arterial pressure (mean difference (95% CI), -3.39 mm Hg (-6.79 to 0.01); p=0.05 and -2.20 mm Hg (-4.36 to -0.03); p=0.05 and -4.40 mm Hg (-7.49 to -1.30); p=0.005, respectively). It was associated with increased walk distance in the context of pulmonary rehabilitation (standardised mean difference (95% CI), 0.47 (0.11 to 0.83), p=0.01), but no effect was identified in short-term studies (0.08 (-0.32 to 0.49). Conclusion: Dietary nitrate supplementation may have a beneficial effect on BP and augment the effect of pulmonary rehabilitation on exercise capacity. Short-term studies do not suggest a consistent benefit on exercise capacity.
Oral nitrate supplementation to enhance pulmonary rehabilitation in COPD: ON-EPIC a multicentre, double-blind, placebo-controlled, randomised parallel group study Affiliations
1 National Heart and Lung Institute, Royal Brompton Campus, Imperial College London, London, UK.
2 Respiratory Medicine, Royal Brompton and Harefield NHS Foundation Trust, London, UK.
3 Greenwich Adult Community Health Service, Oxleas NHS Foundation Trust, Dartford, Kent, UK.
4 Respiratory Medicine, Maidstone and Tunbridge Wells NHS Trust, Maidstone, Kent, UK.
5 Musgrove Park Hospital, Taunton and Somerset NHS Foundation Trust, Taunton, Somerset, UK.
6 National Heart and Lung Institute, Royal Brompton Campus, Imperial College London, London, UK firstname.lastname@example.org.