title: A randomized controlled trial of green tea catechins in protection against ultraviolet radiation-induced cutaneous inflammation.
abstract: Safe systemic protection from the health hazards of ultraviolet radiation (UVR) in sunlight is desirable. Green tea is consumed globally and is reported to have anti-inflammatory properties, which may be mediated through the impact on cyclooxygenase and lipoxygenase pathways. Recent data suggest that green tea catechins (GTCs) reduce acute UVR effects, but human trials examining their photoprotective potential are scarce.
  
  
  
  We performed a double-blind, randomized, placebo-controlled trial to examine whether GTCs protect against clinical, histologic, and biochemical indicators of UVR-induced inflammation.
  
  
  
  Healthy adults (aged 18-65 y, phototypes I-II) were randomly allocated to 1350 mg encapsulated green tea extract (540 mg GTC) with 50 mg vitamin C or placebo twice daily for 3 mo. Impact on skin erythema, dermal leukocytic infiltration, and concentrations of proinflammatory eicosanoids was assessed after solar-simulated UVR challenge, and subject compliance was determined through assay of urinary GTC metabolite epigallocatechin glucuronide.
  
  
  
  Volunteers were assigned to the active (n = 25) or the placebo (n = 25) group. After supplementation, median (IQR) sunburn threshold (minimal erythema dose) was 28 (20-28) and 20 (20-28) mJ/cm(2) in the active and placebo groups, respectively (nonsignificant), with no difference in AUC analysis for measured erythema index after a geometric series of 10 UVR doses. Skin immunohistochemistry showed increased neutrophil and CD3(+) T-lymphocyte numbers post-UVR in both groups (P < 0.01) with no statistically significant differences between groups after supplementation. Cyclooxygenase and lipoxygenase metabolites prostaglandin E2 (vasodilator) and 12-hydroxyeicosatetraenoicacid (chemoattractant), respectively, increased after UVR (P < 0.05), with no differences between supplementation groups.
  
  
  
  Oral GTC (1080 mg/d) with vitamin C over 3 mo did not significantly reduce skin erythema, leukocyte infiltration, or eicosanoid response to UVR inflammatory challenge. This trial was registered at clinicaltrials.gov as NCT01032031.
authors.affiliation: Centre for Dermatology, Institute of Inflammation and Repair, University of Manchester, Manchester Academic Health Science Centre, Salford Royal NHS Foundation Trust, Manchester, United Kingdom;
authors.forename: Mark D
authors.identifier: http://orcid.org/0000-0001-8602-7279
authors.initials: MD
authors.lastname: Farrar
authors.affiliation: Manchester Pharmacy School, Faculty of Medical and Human Sciences, University of Manchester, Manchester, United Kingdom;
authors.forename: Anna
authors.identifier: http://orcid.org/0000-0002-1314-413X
authors.initials: A
authors.lastname: Nicolaou
authors.affiliation: School of Food Science and Nutrition, University of Leeds, Leeds, United Kingdom; and.
authors.forename: Kayleigh A
authors.initials: KA
authors.lastname: Clarke
authors.affiliation: Centre for Dermatology, Institute of Inflammation and Repair, University of Manchester, Manchester Academic Health Science Centre, Salford Royal NHS Foundation Trust, Manchester, United Kingdom;
authors.forename: Sarah
authors.initials: S
authors.lastname: Mason
authors.affiliation: Bradford School of Pharmacy, Faculty of Life Sciences, University of Bradford, Bradford, United Kingdom.
authors.forename: Karen A
authors.initials: KA
authors.lastname: Massey
authors.affiliation: Bradford School of Pharmacy, Faculty of Life Sciences, University of Bradford, Bradford, United Kingdom.
authors.forename: Tristan P
authors.initials: TP
authors.lastname: Dew
authors.affiliation: Centre for Dermatology, Institute of Inflammation and Repair, University of Manchester, Manchester Academic Health Science Centre, Salford Royal NHS Foundation Trust, Manchester, United Kingdom;
authors.forename: Rachel E B
authors.identifier: http://orcid.org/0000-0002-5162-7503
authors.initials: RE
authors.lastname: Watson
authors.affiliation: School of Food Science and Nutrition, University of Leeds, Leeds, United Kingdom; and.
authors.forename: Gary
authors.initials: G
authors.lastname: Williamson
authors.affiliation: Centre for Dermatology, Institute of Inflammation and Repair, University of Manchester, Manchester Academic Health Science Centre, Salford Royal NHS Foundation Trust, Manchester, United Kingdom; lesley.e.rhodes@manchester.ac.uk.
authors.forename: Lesley E
authors.identifier: http://orcid.org/0000-0002-9107-6654
authors.initials: LE
authors.lastname: Rhodes
mesh_terms: D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid / Q000378:metabolism; D000284:Administration, Oral; D000328:Adult; D000975:Antioxidants / Q000494:pharmacology; D001205:Ascorbic Acid / Q000494:pharmacology; D002392:Catechin / Q000494:pharmacology* / Q000652:urine; D019587:Dietary Supplements; D015232:Dinoprostone / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004890:Erythema / Q000188:drug therapy; D005260:Female; D006801:Humans; D007249:Inflammation / Q000188:drug therapy* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D012867:Skin / Q000187:drug effects; D013471:Sunburn / Q000188:drug therapy / Q000209:etiology; D013662:Tea / Q000737:chemistry*; D014466:Ultraviolet Rays / Q000009:adverse effects*; D055815:Young Adult
chemical_list: D000975:Antioxidants; D013662:Tea; D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; D002392:Catechin; D015232:Dinoprostone; D001205:Ascorbic Acid
keywords: green tea catechins; human skin; inflammation; photoprotection; ultraviolet radiation