title: Unfiltered coffee increases plasma homocysteine concentrations in healthy volunteers: a randomized trial.
abstract: BACKGROUND
  An elevated plasma homocysteine concentration is a putative risk factor for cardiovascular disease. Observational studies have reported an association between coffee consumption and plasma homocysteine concentrations.
  
  
  OBJECTIVE
  We studied the effect of coffee consumption on plasma homocysteine in a crossover trial. We used unfiltered coffee so as to include the possible effects of coffee diterpenes, which are removed by filtering.
  
  
  METHODS
  Sixty-four healthy volunteers (31 men and 33 women) with a mean (+/-SD) age of 43 +/- 11 y were randomly assigned to 2 groups. One group (n = 30) drank 1 L unfiltered cafetière (French press) coffee daily for 2 wk. Such coffee is rich in the cholesterol-raising diterpenes kahweol and cafestol. The other group (n = 34) received water, milk, broth, tea, and chocolate drinks instead of coffee. After a washout period of 8 wk, both groups received the alternate intervention for another 2 wk.
  
  
  RESULTS
  Consumption of 1 L unfiltered coffee/d for 2 wk significantly raised fasting plasma homocysteine concentrations by 10%, from 12.8 to 14.0 micromol/L.
  
  
  CONCLUSIONS
  Unfiltered coffee increases plasma homocysteine concentrations in volunteers with normal initial concentrations. It is unclear whether the effect is caused by the cholesterol-raising diterpenes present exclusively in unfiltered coffee or by factors that are also present in filtered coffee.
authors.affiliation: Departments of Gastroenterology and Hepatology, Internal Medicine, Pediatrics, and Clinical Chemistry, University Hospital Nijmegen, Netherlands. M.Grubben@gastro.azn.nl
authors.forename: M J
authors.initials: MJ
authors.lastname: Grubben
authors.forename: G H
authors.initials: GH
authors.lastname: Boers
authors.forename: H J
authors.initials: HJ
authors.lastname: Blom
authors.forename: R
authors.initials: R
authors.lastname: Broekhuizen
authors.forename: R
authors.initials: R
authors.lastname: de Jong
authors.forename: L
authors.initials: L
authors.lastname: van Rijt
authors.forename: E
authors.initials: E
authors.lastname: de Ruijter
authors.forename: D W
authors.initials: DW
authors.lastname: Swinkels
authors.forename: F M
authors.initials: FM
authors.lastname: Nagengast
authors.forename: M B
authors.initials: MB
authors.lastname: Katan
mesh_terms: D000328:Adult; D000368:Aged; D000410:Alanine Transaminase / Q000097:blood; D002318:Cardiovascular Diseases / Q000378:metabolism; D003069:Coffee / Q000378:metabolism*; D018592:Cross-Over Studies; D004032:Diet; D005260:Female; D006710:Homocysteine / Q000097:blood / Q000378:metabolism*; D006801:Humans; D008055:Lipids / Q000097:blood; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D014815:Vitamins / Q000097:blood
chemical_list: D003069:Coffee; D008055:Lipids; D014815:Vitamins; D006710:Homocysteine; D000410:Alanine Transaminase