title: Moderate coffee consumption increases plasma glutathione but not homocysteine in healthy subjects.
abstract: BACKGROUND
  The consumption of unfiltered coffee, containing bioactive diterpenes, causes an increase in plasma homocysteine concentration. A slight increase in plasma homocysteine is also caused by large quantities of filtered coffee. Coffee terpenes also raise plasma glutathione in mice.
  
  
  OBJECTIVE
  To verify the effect of Italian-style coffee consumption on the plasma concentration of glutathione and homocysteine in healthy subjects.
  
  
  METHODS
  Twenty-two volunteers consumed five cups of coffee per day for 1 week and maintained their usual diet. Five subjects were enrolled as controls. The intervention trial was preceded and followed by seven coffee-free days.
  
  
  RESULTS
  Plasma glutathione increased by 16% (P < 0.05) on coffee consumption, and returned to the original concentration after the washout period. The increase in plasma homocysteine concentration (13% after 1 week of coffee intake) was not significant. No differences in glutathione or homocysteine concentration were observed in the control group. No variation of plasma hydroperoxide concentration was detectable.
  
  
  CONCLUSIONS
  A coffee intake regimen, representing the average consumption of coffee drinkers in Italy, increased the plasma concentration of glutathione, but no significant increase in the plasma homocysteine concentration was detected.
authors.affiliation: Dipartimento di Scienza degli Alimenti, Università di Napoli Federico II, Napoli, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Esposito
authors.forename: F
authors.initials: F
authors.lastname: Morisco
authors.forename: V
authors.initials: V
authors.lastname: Verde
authors.forename: A
authors.initials: A
authors.lastname: Ritieni
authors.forename: A
authors.initials: A
authors.lastname: Alezio
authors.forename: N
authors.initials: N
authors.lastname: Caporaso
authors.forename: V
authors.initials: V
authors.lastname: Fogliano
mesh_terms: D000328:Adult; D001628:Beverages; D003069:Coffee; D004326:Drinking; D005260:Female; D005978:Glutathione / Q000097:blood*; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D008297:Male
chemical_list: D003069:Coffee; D006710:Homocysteine; D005978:Glutathione