title: Coffee consumption and circulating B-vitamins in healthy middle-aged men and women.
abstract: BACKGROUND
  Coffee consumption has been associated with several risk factors for coronary heart disease, including increased cholesterol, increased blood pressure, and increased plasma total homocysteine (tHcy). tHcy is determined by several B-vitamins. However, reports about the association between coffee intake and B-vitamin status are few.
  
  
  METHODS
  We measured plasma B-vitamins and tHcy in a cohort of 10,601 healthy, middle-aged Norwegian men and women. Information about lifestyle factors, including coffee consumption, smoking, alcohol use, height, and weight, was obtained by interview.
  
  
  RESULTS
  Coffee consumption was dose-dependently associated with reduced plasma B-vitamin concentrations. Compared with coffee abstainers, individuals drinking >or=4 cups/day had 11.7% (P < 0.001), 14.1% (P < 0.001), and 5.5% (P = 0.01) lower plasma concentrations of folate, pyridoxal phosphate, and riboflavin, respectively, and the mean tHcy concentration was 6.8% (P < 0.001) higher. Quantile regression analysis showed essentially no difference in B-vitamin concentrations between coffee consumption categories at low vitamin concentrations but a progressive increase in the difference at higher concentrations. This pattern of differences (effect profile) was found independently of smoking status, alcohol intake, and sex. The decrease in folate explained approximately half of the increase in tHcy.
  
  
  CONCLUSIONS
  Coffee consumption was associated with reduced circulating B-vitamin concentrations. The observed effect profiles indicated that coffee consumption preferentially affected the upper, but not the lower, part of the B-vitamin concentration distributions. We hypothesize that coffee consumption may increase the loss of surplus B-vitamins by excretion in urine.
authors.affiliation: LOCUS for Homocysteine and Related Vitamins, Department of Internal Medicine, Pharmacology Section, University of Bergen, Bergen, Norway. arve.ulvik@farm.uib.no
authors.forename: Arve
authors.initials: A
authors.lastname: Ulvik
authors.forename: Stein Emil
authors.initials: SE
authors.lastname: Vollset
authors.forename: Geir
authors.initials: G
authors.lastname: Hoff
authors.forename: Per Magne
authors.initials: PM
authors.lastname: Ueland
mesh_terms: D000428:Alcohol Drinking / Q000453:epidemiology; D015992:Body Mass Index; D003069:Coffee; D005260:Female; D005492:Folic Acid / Q000097:blood; D006262:Health; D006710:Homocysteine / Q000097:blood; D006801:Humans; D008019:Life Style; D008297:Male; D008875:Middle Aged; D012907:Smoking / Q000453:epidemiology; D014803:Vitamin B Complex / Q000097:blood* / Q000652:urine
chemical_list: D003069:Coffee; D006710:Homocysteine; D014803:Vitamin B Complex; D005492:Folic Acid