title: Effects of dietary nitrate supplementation on the oxygen cost of exercise and walking performance in individuals with type 2 diabetes: a randomized, double-blind, placebo-controlled crossover trial.
abstract: Dietary nitrate supplementation has been shown to reduce the oxygen (O2) cost of exercise and enhance exercise tolerance in healthy individuals. This study assessed whether similar effects could be observed in individuals with type 2 diabetes (T2DM). In a randomized, double-blind, placebo-controlled crossover study, 48 participants with T2DM supplemented their diet for 4 days with either nitrate-rich beetroot juice (70ml/day, 6.43mmol nitrate/day) or nitrate-depleted beetroot juice as placebo (70ml/day, 0.07mmol nitrate/day). After each intervention period, resting plasma nitrate and nitrite concentrations were measured subsequent to participants completing moderate-paced walking. Pulmonary gas exchange was measured to assess the O2 cost of walking. After a rest period, participants performed the 6-min walk test (6MWT). Relative to placebo, beetroot juice resulted in a significant increase in plasma nitrate (placebo, 57±66 vs beetroot, 319±110µM; P < 0.001) and plasma nitrite concentration (placebo, 680±256 vs beetroot, 1065±607nM; P < 0.001). There were no differences between placebo juice and beetroot juice for the O2 cost of walking (946±221 vs 939±223ml/min, respectively; P = 0.59) and distance covered in the 6MWT (550±83 vs 554±90m, respectively; P = 0.17). Nitrate supplementation did not affect the O2 cost of moderate-paced walking or improve performance in the 6MWT. These findings indicate that dietary nitrate supplementation does not modulate the response to exercise in individuals with T2DM.
authors.affiliation: College of Life and Environmental Sciences, Sport and Health Sciences, University of Exeter, Exeter EX1 2LU, Devon, UK; University of Exeter Medical School and NIHR Exeter Clinical Research Facility, Royal Devon and Exeter Hospital, Exeter, Devon, UK.
authors.forename: Anthony I
authors.initials: AI
authors.lastname: Shepherd
authors.affiliation: University of Exeter Medical School and NIHR Exeter Clinical Research Facility, Royal Devon and Exeter Hospital, Exeter, Devon, UK.
authors.forename: Mark
authors.initials: M
authors.lastname: Gilchrist
authors.affiliation: University of Exeter Medical School and NIHR Exeter Clinical Research Facility, Royal Devon and Exeter Hospital, Exeter, Devon, UK.
authors.forename: Paul G
authors.initials: PG
authors.lastname: Winyard
authors.affiliation: College of Life and Environmental Sciences, Sport and Health Sciences, University of Exeter, Exeter EX1 2LU, Devon, UK.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Jones
authors.affiliation: Warsaw University of Life Sciences, Warsaw, Poland.
authors.forename: Ewelina
authors.initials: E
authors.lastname: Hallmann
authors.affiliation: Warsaw University of Life Sciences, Warsaw, Poland.
authors.forename: Renata
authors.initials: R
authors.lastname: Kazimierczak
authors.affiliation: Warsaw University of Life Sciences, Warsaw, Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Rembialkowska
authors.affiliation: University of Exeter Medical School and NIHR Exeter Clinical Research Facility, Royal Devon and Exeter Hospital, Exeter, Devon, UK.
authors.forename: Nigel
authors.initials: N
authors.lastname: Benjamin
authors.affiliation: University of Exeter Medical School and NIHR Exeter Clinical Research Facility, Royal Devon and Exeter Hospital, Exeter, Devon, UK.
authors.forename: Angela C
authors.initials: AC
authors.lastname: Shore
authors.affiliation: College of Life and Environmental Sciences, Sport and Health Sciences, University of Exeter, Exeter EX1 2LU, Devon, UK. Electronic address: d.p.wilkerson@ex.ac.uk.
authors.forename: Daryl P
authors.initials: DP
authors.lastname: Wilkerson
mesh_terms: D000368:Aged; D000975:Antioxidants / Q000032:analysis; D027461:Beta vulgaris / Q000737:chemistry; D003131:Combined Modality Therapy; D018592:Cross-Over Studies; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism / Q000628:therapy*; D019587:Dietary Supplements; D004311:Double-Blind Method; D005081:Exercise Therapy; D005260:Female; D000067030:Fruit and Vegetable Juices / Q000032:analysis; D006801:Humans; D008297:Male; D008875:Middle Aged; D009566:Nitrates / Q000008:administration & dosage*; D010101:Oxygen Consumption; D016896:Treatment Outcome; D016138:Walking
chemical_list: D000975:Antioxidants; D009566:Nitrates
keywords: Blood pressure; Exercise; Free radicals; Nitrate; Nitric oxide; Type 2 diabetes