title: Dietary nitrate supplementation in COPD: an acute, double-blind, randomized, placebo-controlled, crossover trial.
abstract: BACKGROUND
  The acute consumption of dietary nitrate has been shown to improve exercise capacity in athletes, healthy adults and subjects with peripheral vascular disease. Many COPD patients have reduced exercise capacity. We hypothesized that acute nitrate consumption might increase incremental shuttle walk test (ISWT) distance in COPD subjects.
  
  
  METHODS
  Eleven COPD subjects were randomly assigned to consume either a high nitrate or a matched, low nitrate beverage in a double-blind, randomized, placebo-controlled, crossover design. ISWT distance was measured both before and 3 h after the beverage and change was recorded. After a 7-day washout, ISWT distances were re-measured before and 3 h after the alternate beverage and changes were recorded.
  
  
  RESULTS
  We observed an increase in ISWT distance after consuming the high nitrate juice (25 m) compared with a reduction after the low nitrate juice (14 m) (p < 0.01). This improvement in exercise capacity was associated with significant increases in serum nitrate (p < 0.000005) and nitrite (p < 0.01) levels and a significant lowering of resting blood pressure (<0.05).
  
  
  CONCLUSIONS
  In patients with stable COPD, the acute consumption of dietary nitrate increased serum nitrate/nitrite levels and exercise capacity and was associated with a decrease in resting blood pressure. Nitrate consumption might alter exercise capacity in COPD patients.
authors.affiliation: Respiratory and Sleep Diagnostics Department, Connolly Hospital, Blanchardstown, Dublin 15, Ireland; School of Medicine and Medical Sciences, University College Dublin, Belfield, Dublin 4, Ireland. Electronic address: kerleyc@tcd.ie.
authors.forename: Conor P
authors.initials: CP
authors.lastname: Kerley
authors.affiliation: Respiratory and Sleep Diagnostics Department, Connolly Hospital, Blanchardstown, Dublin 15, Ireland.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Cahill
authors.affiliation: Respiratory and Sleep Diagnostics Department, Connolly Hospital, Blanchardstown, Dublin 15, Ireland.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Bolger
authors.affiliation: Respiratory and Sleep Diagnostics Department, Connolly Hospital, Blanchardstown, Dublin 15, Ireland.
authors.forename: Aisling
authors.initials: A
authors.lastname: McGowan
authors.affiliation: Respiratory and Sleep Diagnostics Department, Connolly Hospital, Blanchardstown, Dublin 15, Ireland.
authors.forename: Conor
authors.initials: C
authors.lastname: Burke
authors.affiliation: Respiratory and Sleep Diagnostics Department, Connolly Hospital, Blanchardstown, Dublin 15, Ireland.
authors.forename: John
authors.initials: J
authors.lastname: Faul
authors.affiliation: Respiratory and Sleep Diagnostics Department, Connolly Hospital, Blanchardstown, Dublin 15, Ireland.
authors.forename: Liam
authors.initials: L
authors.lastname: Cormican
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001794:Blood Pressure / Q000187:drug effects; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005080:Exercise Test / Q000187:drug effects; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D009566:Nitrates / Q000008:administration & dosage* / Q000097:blood; D009569:Nitric Oxide / Q000097:blood; D009573:Nitrites / Q000097:blood; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood / Q000178:diet therapy* / Q000503:physiopathology; D016138:Walking
chemical_list: D009566:Nitrates; D009573:Nitrites; D009569:Nitric Oxide
keywords: Beetroot; COPD; Dietary nitrate; Exercise tolerance; Nitric oxide; Nitrite