title: Acute black tea consumption improves cutaneous vascular function in healthy middle-aged humans.
abstract: Dietary flavonoids, such as those present in black tea, are associated with reduced risk of cardiovascular disease (CVD), possibly through improving nitric oxide (NO) mediated vascular function. The aim of this study was to examine the effect of acute black tea ingestion on cutaneous microvascular function.
  
  
  
  Twenty healthy participants (58 ± 5 y, 9 men) attended two experimental trials (tea, placebo), 7-days apart in a randomised, controlled, double-blind, cross-over design. Participants ingested a single dose of 200 ml black tea or placebo, followed by assessment of forearm cutaneous perfusion using laser-Doppler flowmetry (LDF) using three distinct heating protocols, enabling us to distinguish between axon- and endothelium-dependent vasodilation: 1. rapid 42°C, 2. rapid 39°C and 3. gradual 42°C. On the contralateral arm, full-field laser perfusion imaging (FLPI) was used to assess forearm perfusion during gradual 42°C. Data were presented as cutaneous vascular conductance (CVC; flux/mean arterial pressure, MAP) and CVC expressed as a percentage of maximal CVC (%CVCmax).
  
  
  
  Rapid local heating to 39°C or 42°C demonstrated no effect of tea for flux, CVC or %CVCmax(all P > 0.05). Gradual local heating to 42 °C, however, produced a higher skin blood flow following black tea ingestion for absolute CVC (P = 0.04) when measured by LDF, and higher absolute flux (P < 0.001) and CVC (P < 0.001) measured with FLPI. No effect of tea was found for %CVCmaxwhen assessed by either LDF or FLPI.
  
  
  
  Acute tea ingestion enhanced cutaneous vascular responses to gradual local heating to 42 °C in healthy, middle-aged participants, possibly through a mechanism related to activation of endothelium-derived chemical mediators, such as NO. These improvements may contribute to the cardiovascular health benefits of regular tea ingestion.
authors.affiliation: Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK.
authors.forename: Kirsty A
authors.initials: KA
authors.lastname: Woodward
authors.affiliation: Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK.
authors.forename: Nicola D
authors.initials: ND
authors.lastname: Hopkins
authors.affiliation: Unilever Research & Development, Olivier van Noortlaan 120, 3133 AT, Vlaardingen, The Netherlands.
authors.forename: Richard
authors.initials: R
authors.lastname: Draijer
authors.affiliation: Unilever Research & Development, Olivier van Noortlaan 120, 3133 AT, Vlaardingen, The Netherlands.
authors.forename: Young
authors.initials: Y
authors.lastname: de Graaf
authors.affiliation: Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK.
authors.forename: David A
authors.initials: DA
authors.lastname: Low
authors.affiliation: Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK; Radboud Institute for Health Sciences, Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands. Electronic address: d.thijssen@ljmu.ac.uk.
authors.forename: Dick H J
authors.initials: DHJ
authors.lastname: Thijssen
mesh_terms: D001132:Arm / Q000098:blood supply* / Q000000981:diagnostic imaging; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D005419:Flavonoids; D006801:Humans; D008297:Male; D008833:Microcirculation / Q000187:drug effects / Q000502:physiology; D008875:Middle Aged; D055420:Perfusion Imaging; D012867:Skin / Q000098:blood supply* / Q000000981:diagnostic imaging; D013662:Tea
chemical_list: D005419:Flavonoids; D013662:Tea
keywords: Cardiovascular health; Flavonoids; Microcirculation; Tea; Vascular function