title: The plasma bioavailability of nitrate and betanin from Beta vulgaris rubra in humans.
abstract: OBJECTIVE
  To evaluate the plasma bioavailability of betanin and nitric oxide (NOx) after consuming beetroot juice (BTJ) and whole beetroot (BF). BTJ and BF were also analysed for antioxidant capacity, polyphenol content (TPC) and betalain content.
  
  
  METHODS
  Ten healthy males consumed either 250 ml of BTJ, 300 g of BF or a placebo drink, in a randomised, crossover design. Venous plasma samples were collected pre (baseline), 1, 2, 3, 5 and 8 h post-ingestion. Betanin content in BTJ, BF and plasma was analysed with reverse-phase high-performance liquid chromatography (HPLC) and mass spectrometry detection (LCMS). Antioxidant capacity was estimated using the Trolox equivalent antioxidant capacity (TEAC) and polyphenol content using Folin-Ciocalteu colorimetric methods [gallic acid equivalents (GAE)] and betalain content spectrophotometrically.
  
  
  RESULTS
  TEAC was 11.4 ± 0.2 mmol/L for BTJ and 3.4 ± 0.4 μmol/g for BF. Both BTJ and BF contained a number of polyphenols (1606.9 ± 151 mg/GAE/L and 1.67 ± 0.1 mg/GAE/g, respectively), betacyanins (68.2 ± 0.4 mg/betanin equivalents/L and 19.6 ± 0.6 mg/betanin equivalents/100 g, respectively) and betaxanthins (41.7 ± 0.7 mg/indicaxanthin equivalents/L and 7.5 ± 0.2 mg/indicaxanthin equivalents/100 g, respectively). Despite high betanin contents in both BTJ (~194 mg) and BF (~66 mg), betanin could not be detected in the plasma at any time point post-ingestion. Plasma NOx was elevated above baseline for 8 h after consuming BTJ and 5 h after BF (P < 0.05).
  
  
  CONCLUSIONS
  These data reveal that BTJ and BF are rich in phytonutrients and may provide a useful means of increasing plasma NOx bioavailability. However, betanin, the major betalain in beetroot, showed poor bioavailability in plasma.
authors.affiliation: Department of Sport, Exercise and Rehabilitation, Faculty of Health and Life Sciences, Northumbria University, Newcastle-upon-Tyne, NE1 8ST, UK. tom.clifford@northumbria.ac.uk.
authors.forename: Tom
authors.initials: T
authors.lastname: Clifford
authors.affiliation: Department of Sport, Exercise and Rehabilitation, Faculty of Health and Life Sciences, Northumbria University, Newcastle-upon-Tyne, NE1 8ST, UK.
authors.forename: Costas M
authors.initials: CM
authors.lastname: Constantinou
authors.affiliation: Department of Sport, Exercise and Rehabilitation, Faculty of Health and Life Sciences, Northumbria University, Newcastle-upon-Tyne, NE1 8ST, UK.
authors.forename: Karen M
authors.initials: KM
authors.lastname: Keane
authors.affiliation: Institute of Cellular Medicine, Newcastle University, Newcastle-upon-Tyne, UK.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: West
authors.affiliation: Department of Sport, Exercise and Rehabilitation, Faculty of Health and Life Sciences, Northumbria University, Newcastle-upon-Tyne, NE1 8ST, UK.|Water Research Group, School of Environmental Sciences and Development, Northwest University, Potchefstroom, South Africa.
authors.forename: Glyn
authors.initials: G
authors.lastname: Howatson
authors.affiliation: Institute of Cellular Medicine, Newcastle University, Newcastle-upon-Tyne, UK.
authors.forename: Emma J
authors.initials: EJ
authors.lastname: Stevenson
mesh_terms: D000328:Adult; D000975:Antioxidants / Q000008:administration & dosage / Q000493:pharmacokinetics; D027461:Beta vulgaris / Q000737:chemistry*; D050859:Betacyanins / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics; D050858:Betalains / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D050860:Betaxanthins / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics; D001682:Biological Availability; D002851:Chromatography, High Pressure Liquid; D018592:Cross-Over Studies; D000067030:Fruit and Vegetable Juices; D006801:Humans; D008297:Male; D009566:Nitrates / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D009569:Nitric Oxide / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics; D018517:Plant Roots / Q000737:chemistry; D059808:Polyphenols / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics; D011725:Pyridines / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics; D055815:Young Adult
chemical_list: D000975:Antioxidants; D050859:Betacyanins; D050860:Betaxanthins; D009566:Nitrates; D059808:Polyphenols; D011725:Pyridines; C469628:indicaxanthin; D009569:Nitric Oxide; D050858:Betalains
keywords: Antioxidant; Beetroot; Betalains; Bioavailability; Nitric oxide