title: Dietary nitrate supplementation improves reaction time in type 2 diabetes: development and application of a novel nitrate-depleted beetroot juice placebo.
abstract: BACKGROUND
  In this substudy of the effect of dietary nitrate on blood pressure, endothelial function, and insulin sensitivity in type 2 diabetes, we report the development of a novel nitrate depleted beetroot juice for use clinical trials and determine if dietary nitrate supplementation improved cognitive function in patients with type 2 diabetes mellitus.
  
  
  METHODS
  Beetroot juice was treated with the anion exchange resin Purolite A520e. UV-vis-spectrophotometry, and a blind taste test were performed along with determination of sugar content, measurement of ascorbate and dehydroascorbate, the ionic composition of juice and Proton NMR. Subsequently, 27 patients, age 67.2±4.9 years, (18 male) were recruited for a double blind, randomised, placebo-controlled crossover trial. Participants were randomised to begin in either order beetroot juice (nitrate content 7.5 mmol per 250 ml) or placebo (nitrate depleted beetroot juice nitrate content 0.002 mmol per 250 ml). At the end of each 2 week supplementation period cognitive function was assessed using E-prime, E-Studio software with 5 separate tests being performed. The tests utilised in the present study have been adapted from the Cambridge Neuropsychological Test Automated Battery (CANTAB).
  
  
  RESULTS
  The differences in the UV-vis spectra were comparable to the natural variation found in differing cultivars. There were no discernable differences in taste, sugar content, or Proton NMR. Ascorbate and dehydroascorbate were undetectable in either juice. After 2 weeks of beetroot juice simple reaction time was significantly quicker in the active arm at 327±40 ms versus 341.8±52.7 ms in the placebo arm, mean difference 13.9±25.6 ms (95% CI 3.8-24.0 ms), p=0.009. No other measures of cognitive function differed between treatment arms.
  
  
  CONCLUSIONS
  We have developed an effective placebo beetroot juice for use in trials of supplementation of dietary nitrate. Two weeks supplementation of the diet with 7.5 mmol of nitrate per day caused a significant improvement in simple reaction time in individuals with T2DM.
authors.affiliation: NIHR Exeter Clinical Research Facility and Institute of Biomedical and Clinical Science, University of Exeter Medical School (Previously Peninsula College of Medicine and Dentistry), University of Exeter, Exeter EX2 5AX, UK. Electronic address: m.gilchrist@exeter.ac.uk.
authors.forename: Mark
authors.initials: M
authors.lastname: Gilchrist
authors.affiliation: NIHR Exeter Clinical Research Facility and Institute of Biomedical and Clinical Science, University of Exeter Medical School (Previously Peninsula College of Medicine and Dentistry), University of Exeter, Exeter EX2 5AX, UK.
authors.forename: Paul G
authors.initials: PG
authors.lastname: Winyard
authors.affiliation: NIHR Exeter Clinical Research Facility and Institute of Biomedical and Clinical Science, University of Exeter Medical School (Previously Peninsula College of Medicine and Dentistry), University of Exeter, Exeter EX2 5AX, UK.
authors.forename: Jon
authors.initials: J
authors.lastname: Fulford
authors.affiliation: NIHR Exeter Clinical Research Facility and Institute of Biomedical and Clinical Science, University of Exeter Medical School (Previously Peninsula College of Medicine and Dentistry), University of Exeter, Exeter EX2 5AX, UK.
authors.forename: Christine
authors.initials: C
authors.lastname: Anning
authors.affiliation: NIHR Exeter Clinical Research Facility and Institute of Biomedical and Clinical Science, University of Exeter Medical School (Previously Peninsula College of Medicine and Dentistry), University of Exeter, Exeter EX2 5AX, UK.
authors.forename: Angela C
authors.initials: AC
authors.lastname: Shore
authors.affiliation: NIHR Exeter Clinical Research Facility and Institute of Biomedical and Clinical Science, University of Exeter Medical School (Previously Peninsula College of Medicine and Dentistry), University of Exeter, Exeter EX2 5AX, UK.
authors.forename: Nigel
authors.initials: N
authors.lastname: Benjamin
mesh_terms: D000368:Aged; D027461:Beta vulgaris / Q000737:chemistry*; D001628:Beverages; D018592:Cross-Over Studies; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy*; D019587:Dietary Supplements; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D009566:Nitrates / Q000008:administration & dosage* / Q000494:pharmacology / Q000627:therapeutic use*; D010919:Placebos; D011930:Reaction Time / Q000187:drug effects*
chemical_list: D009566:Nitrates; D010919:Placebos
keywords: Beetroot juice; Beetroot placebo; Cognitive function; Dietary nitrate; Nitrate depleted placebo; Nitrite; Reaction time; Type 2 diabetes