title: Black tea improves endothelial function in renal transplant recipients.
abstract: BACKGROUND
  Endothelial damage and dysfunction are commonplace in renal transplant recipients. Impaired endothelial function is an important contributor to cardiovascular diseases. We hypothesized that short-term black tea consumption may improve endothelium-dependent arterial dilation in kidney recipients.
  
  
  METHODS
  Fifteen recipients were studied on an outpatient basis in a single, university-affiliated clinic. Inclusion criteria were stable and good allograft function. The main exclusion criteria were uncontrolled hypertension, smoking, alcohol consumption, coffee drinking, diabetes mellitus, and coronary artery disease, or a history of upper limb vascular manipulations. After overnight fasting, the brachial artery diameter (BAD) was measured at the end of diastole using an ultrasound machine before (basal BAD) and 1 minute after temporary ( approximately 3 minutes) external occlusion (posthyperemia BAD). Flow-mediated vasodilation (FMV) and percent of FMV (FMV%) were calculated by appropriate formula. FMV and FMV% were determined at baseline and 2 hours after consuming 0.5 L freshly brewed black tea. For control, the study was repeated for each patient the next day and FMV and FMV% were determined before and 2 hours after consuming 0.5 L of water.
  
  
  RESULTS
  The men age of patients was 37.2 +/- 9.7 years (range, 25 to 50) with a male:female ratio of 3:2. Patients were 26.8 +/- 10.6 months postrenal transplantation. Black tea consumption significantly increased posthyperemia BAD, FMV, and FMV% (P<.05). However, water consumption did not alter the basal or posthyperemia BAD, FMV, or FMV% (P>.05).
  
  
  CONCLUSIONS
  Based on our study, short-term consumption of black tea may improve endothelial function and endothelium-dependent arterial vasodilation in renal transplant recipients.
authors.affiliation: Department of Nephrology, Tabriz Medical University, Tabriz, Iran. ardalanm@tbzmed.ac.ir
authors.forename: M R
authors.initials: MR
authors.lastname: Ardalan
authors.forename: M K
authors.initials: MK
authors.lastname: Tarzamni
authors.forename: M M
authors.initials: MM
authors.lastname: Shoja
authors.forename: R S
authors.initials: RS
authors.lastname: Tubbs
authors.forename: B
authors.initials: B
authors.lastname: Rahimi-Ardabili
authors.forename: K
authors.initials: K
authors.lastname: Ghabili
authors.forename: H T
authors.initials: HT
authors.lastname: Khosroshahi
mesh_terms: D000328:Adult; D001916:Brachial Artery; D004730:Endothelium, Vascular / Q000502:physiology*; D005260:Female; D006801:Humans; D016030:Kidney Transplantation / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D018579:Patient Selection; D013662:Tea / Q000502:physiology*; D014184:Transplantation, Homologous; D014664:Vasodilation / Q000502:physiology*
chemical_list: D013662:Tea