title: Hydroxyhydroquinone-free coffee: a double-blind, randomized controlled dose-response study of blood pressure.
abstract: OBJECTIVE
  Coffee is rich in chlorogenic acids (CGA), whose metabolites may have beneficial effects such as anti-hypertensive effects. However, trial results concerning the effects of coffee on blood pressure (BP) are not consistent. A recent study suggested that hydroxyhydroquinone (HHQ), produced by the roasting of green coffee beans, inhibits the effect of CGA. In the present study, the dose-response for CGA in HHQ-free coffee on BP were investigated in mildly hypertensive men and women.
  
  
  RESULTS
  The trial design was a double-blind, randomized controlled trial, with five study groups including, control, zero-dose, low-dose, middle-dose and high-dose. The control beverage was identical to ordinary coffee. The others contained reduced HHQ levels, compared to ordinary coffee, and the CGA were adjusted in target concentration. A total of 203 subjects were randomly allocated. Each subject drank one cup of coffee per day. The study involved a screening and a baseline observation period of 6 weeks and an intervention period of 4 weeks. BP response showed CGA has an anti-hypertensive effect in a dose-dependent manner in HHQ-free coffee, and ordinary coffee showed almost no effect. As a result, a significant correlation between BP change and the three dose-response patterns was observed (p<0.001).
  
  
  CONCLUSIONS
  This study demonstrates a dose-dependent decrease in BP for CGA in HHQ-free coffee.
authors.affiliation: Health Care Food Research Laboratories, Kao Corporation, 2-1-3 Bunka, Sumida, Tokyo 131-8501, Japan. yamaguchi.tohru@kao.co.jp
authors.forename: Tohru
authors.initials: T
authors.lastname: Yamaguchi
authors.forename: Akiro
authors.initials: A
authors.lastname: Chikama
authors.forename: Kenta
authors.initials: K
authors.lastname: Mori
authors.forename: Takuya
authors.initials: T
authors.lastname: Watanabe
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Shioya
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Katsuragi
authors.forename: Ichiro
authors.initials: I
authors.lastname: Tokimitsu
mesh_terms: D000328:Adult; D000368:Aged; D001794:Blood Pressure / Q000187:drug effects*; D002726:Chlorogenic Acid / Q000494:pharmacology*; D003069:Coffee / Q000737:chemistry*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D006873:Hydroquinones / Q000032:analysis*; D006973:Hypertension / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged
chemical_list: D003069:Coffee; D006873:Hydroquinones; C013038:hydroxyhydroquinone; D002726:Chlorogenic Acid