title: Organic grape juice intake improves functional capillary density and postocclusive reactive hyperemia in triathletes.
abstract: OBJECTIVE
  The aim of this study was to evaluate the effect of organic grape juice intake on biochemical variables and microcirculatory parameters in triathlon athletes.
  
  
  BACKGROUND
  The physiological stress that is imposed by a strenuous sport, such as a triathlon, together with an insufficient amount of antioxidants in the diet may cause oxidative imbalance and endothelial dysfunction.
  
  
  METHODS
  Ten adult male triathletes participated in this study. A venous blood sample was drawn before (baseline) and after 20 days of organic grape juice intake (300 ml/day). Serum insulin, plasma glucose and uric acid levels, the total content of polyphenols, and the erythrocyte superoxide dismutase activity were determined. The functional microcirculatory parameters (the functional capillary density, red blood cell velocity at baseline and peak levels, and time required to reach the peak red blood cell velocity during postocclusive reactive hyperemia after a one-min arterial occlusion) were evaluated using nailfold videocapillaroscopy.
  
  
  RESULTS
  Compared with baseline levels, the peak levels of serum insulin ( p = 0.02), plasma uric acid ( p = 0.04), the functional capillary density ( p = 0.003), and the red blood cell velocity (p < 0.001) increased, whereas the plasma glucose level (p,0.001), erythrocyte superoxide dismutase activity ( p = 0.04), and time required to reach red blood cell velocity during postocclusive reactive hyperemia ( p = 0.04) decreased after organic grape juice intake.
  
  
  CONCLUSIONS
  Our data showed that organic grape juice intake improved glucose homeostasis, antioxidant capacity, and microvascular function, which may be due to its high concentration of polyphenols. These results indicate that organic grape juice has a positive effect in endurance athletes.
authors.affiliation: Department of Basic and Experimental Nutrition, State University of Rio de Janeiro, Brazil.
authors.forename: Mariana Correa
authors.initials: MC
authors.lastname: Gonçalves
authors.forename: Flavia Fioruci
authors.initials: FF
authors.lastname: Bezerra
authors.forename: Elis Cristina de Araujo
authors.initials: EC
authors.lastname: Eleutherio
authors.forename: Eliete
authors.initials: E
authors.lastname: Bouskela
authors.forename: Josely
authors.initials: J
authors.lastname: Koury
mesh_terms: D000328:Adult; D056352:Athletes; D001628:Beverages; D001786:Blood Glucose / Q000378:metabolism; D004912:Erythrocytes / Q000201:enzymology; D058870:Food, Organic; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D006940:Hyperemia / Q000378:metabolism*; D007328:Insulin / Q000097:blood; D008297:Male; D008833:Microcirculation / Q000502:physiology; D018384:Oxidative Stress / Q000187:drug effects; D059808:Polyphenols / Q000378:metabolism; D012867:Skin / Q000098:blood supply*; D013312:Stress, Physiological / Q000502:physiology*; D013482:Superoxide Dismutase / Q000378:metabolism; D014527:Uric Acid / Q000097:blood; D027843:Vitis / Q000737:chemistry*
chemical_list: D001786:Blood Glucose; D007328:Insulin; D059808:Polyphenols; D014527:Uric Acid; D013482:Superoxide Dismutase