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A Pilot Study of Dietary Nitrate Supplementation in Anaemic Patients
Date: 30 March 2020
University of Exeter
Doctor of Medicine
Introduction Anaemia causes debilitating symptoms in people with cancer, partly through reduced tissue oxygenation. Nitrate supplementation, via reduction to nitrite then nitric oxide, attenuates the effects of systemic hypoxia on muscle metabolism. Nitric oxide also influences cerebral blood flow, neurotransmission and platelet ...
Introduction Anaemia causes debilitating symptoms in people with cancer, partly through reduced tissue oxygenation. Nitrate supplementation, via reduction to nitrite then nitric oxide, attenuates the effects of systemic hypoxia on muscle metabolism. Nitric oxide also influences cerebral blood flow, neurotransmission and platelet aggregation. Aims To examine the feasibility of recruiting patients with cancer-related anaemia to a pilot study, and to estimate differences in outcome measures and predict resources required for a larger study investigating how nitrate supplementation affects thrombogenicity, muscle phosphocreatine recovery, exercise tolerance, cognition and quality of life. Methods This prospective, balanced randomised crossover study recruited 33 participants. Cycle ergometry, bloods, 31P-magnetic resonance spectroscopy and quality of life & cognition questionnaires were completed at two baseline visits and two visits post-supplementation with either nitrate-rich (BR) or nitrate-depleted (PL) beetroot juice. Results 85% of 33 screened patients were enrolled. 26 completed all visits. Plasma nitrate concentration was 8.4±58.8µM (mean±SD) at baseline and 78±33.5µM post-BR (p=<0.001*). Nitrite was 142±79nM (baseline) and 923±1006nM post-BR (p=0.000*). Haemoglobin concentration was 111.4±9.8g/l (baseline), 109.1±10.9g/l post-BR but 114.6±12g/l post-PL (p=0.028*). FACT-An quality of life score was 146±20 at baseline and improved to 152±24 post-PL and 150±25 post-BR (p=0.025*). Baseline FACT-cog cognitive function was 105±23 and improved to 109±24 post-PL and 108±23 post-BR (p=0.03*). Gas exchange threshold was53±11W post-PL; baseline was 51±12W, BR 50±12W, p=0.0238*. Baseline systolic blood pressure was 122±15mmHg, higher than post-BR (117±15mmHg) and post-PL (116±15mmHg), p=0.0081*). Oxygen uptake, peak power, phosphocreatine recovery, diastolic blood pressure and platelet aggregometry were not significantly affected. Conclusion This pilot study recruited and retained participants well. The enterosalivary circulation of nitrate was intact. The study was not powered to prove or disprove its hypotheses, but demonstrated that clinical factors (particularly haemoglobin concentration which varied because of chemotherapy and cancer progression/response) in this unstable population should influence future study design.
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