title: Associations of coffee consumption with markers of liver injury in the insulin resistance atherosclerosis study.
abstract: BACKGROUND
  Coffee consumption has been associated with reduced risk of developing type 2 diabetes mellitus (T2DM) however, the mechanism for this association has yet to be elucidated. Non-alcoholic fatty liver disease (NAFLD) characterizes and predicts T2DM yet the relationship of coffee with this disorder remains unclear. Our aim was to investigate the associations of coffee with markers of liver injury in 1005 multi-ethnic, non-diabetic adults in the Insulin Resistance Atherosclerosis Study.
  
  
  METHODS
  Dietary intake was assessed using a validated 114-item food frequency questionnaire. Alanine aminotransferase (ALT), aspartate aminotransferase (AST) and fetuin-A were determined in fasting blood samples and the validated NAFLD liver fat score was calculated. Multivariate linear regression assessed the contribution of coffee to variation in markers of liver injury.
  
  
  RESULTS
  Caffeinated coffee showed significant inverse associations with ALT (β = -0.08, p = 0.0111), AST (β = -0.05, p = 0.0155) and NAFLD liver fat score (β = -0.05, p = 0.0293) but not with fetuin-A (β = 0.04, p = 0.17). When the highest alcohol consumers were excluded, these associations remained (ALT β = -0.11, p = 0.0037; AST β = -0.05, p = 0.0330; NAFLD liver fat score β = -0.06, p = 0.0298). With additional adjustment for insulin sensitivity, the relationship with ALT remained significant (ALT β = -0.08, p = 0.0400; AST β = -0.03, p = 0.20; NAFLD liver fat score β = -0.03, p = 0.27). There were no significant associations of decaffeinated coffee with liver markers.
  
  
  CONCLUSIONS
  These analyses indicate a beneficial impact of caffeinated coffee on liver morphology and/or function, and suggest that this relationship may mediate the well-established inverse association of coffee with risk of T2DM.
authors.affiliation: Department of Nutritional Sciences, University of Toronto, Toronto, ON, Canada. jolynn.dickson@sickkids.ca.
authors.forename: J C
authors.initials: JC
authors.lastname: Dickson
authors.affiliation: Department of Epidemiology and Biostatistics, University of South Carolina, Columbia, SC, USA. liese@mailbox.sc.edu.
authors.forename: A D
authors.initials: AD
authors.lastname: Liese
authors.affiliation: Division of Clinical Epidemiology, University of Texas Health Sciences Center at San Antonio, San Antonio, TX, USA. lorenzo@uthscsa.edu.
authors.forename: C
authors.initials: C
authors.lastname: Lorenzo
authors.affiliation: University of Texas Health Science Center, San Antonio, TX, USA. smhaffner1@gmail.com.
authors.forename: S M
authors.initials: SM
authors.lastname: Haffner
authors.affiliation: Lipomics Technologies, West Sacramento, CA, USA. smwatkins@lipomics.com.
authors.forename: S M
authors.initials: SM
authors.lastname: Watkins
authors.affiliation: Singulex, Inc., Alameda, CA, USA. sarahhamren@gmail.com.
authors.forename: S J
authors.initials: SJ
authors.lastname: Hamren
authors.affiliation: Singulex, Inc., Alameda, CA, USA. j.stiles@singulex.com.
authors.forename: J K
authors.initials: JK
authors.lastname: Stiles
authors.affiliation: Division of Public Health Sciences, School of Medicine, Wake Forest University, Winston-Salem, NC, USA. lwgnkcht@wfubmc.edu.
authors.forename: L E
authors.initials: LE
authors.lastname: Wagenknecht
authors.affiliation: Department of Nutritional Sciences, University of Toronto, Toronto, ON, Canada. anthony.hanley@utoronto.ca.|Departments of Medicine and Dalla Lana School of Public Health, University of Toronto and Leadership Sinai Centre for Diabetes, Mt Sinai Hospital, University of Toronto, 150 College Street, Room 341, Toronto, ON, M5S 3E2, Canada. anthony.hanley@utoronto.ca.
authors.forename: A J
authors.initials: AJ
authors.lastname: Hanley
mesh_terms: D000410:Alanine Transaminase / Q000097:blood*; D001219:Aspartate Aminotransferases / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D002110:Caffeine; D003069:Coffee; D003924:Diabetes Mellitus, Type 2 / Q000097:blood; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D016014:Linear Models; D008099:Liver / Q000473:pathology*; D008111:Liver Function Tests; D008297:Male; D008875:Middle Aged; D065626:Non-alcoholic Fatty Liver Disease / Q000097:blood; D065840:Protective Factors; D011795:Surveys and Questionnaires; D060749:alpha-2-HS-Glycoprotein / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D003069:Coffee; D060749:alpha-2-HS-Glycoprotein; D002110:Caffeine; D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase