title: Caffeine, coffee, and tea intake and urinary estrogens and estrogen metabolites in premenopausal women.
abstract: BACKGROUND
  Prior studies have found weak inverse associations between breast cancer and caffeine and coffee intake, possibly mediated through their effects on sex hormones.
  
  
  METHODS
  High-performance liquid chromatography/tandem mass spectrometry was used to quantify levels of 15 individual estrogens and estrogen metabolites (EM) among 587 premenopausal women in the Nurses' Health Study II with mid-luteal phase urine samples and caffeine, coffee, and/or tea intakes from self-reported food frequency questionnaires. Multivariate linear mixed models were used to estimate geometric means of individual EM, pathways, and ratios by intake categories, and P values for tests of linear trend.
  
  
  RESULTS
  Compared with women in the lowest quartile of caffeine consumption, those in the top quartile had higher urinary concentrations of 16α-hydroxyestrone (28% difference; Ptrend = 0.01) and 16-epiestriol (13% difference; Ptrend = 0.04), and a decreased parent estrogens/2-, 4-, 16-pathway ratio (Ptrend = 0.03). Coffee intake was associated with higher 2-catechols, including 2-hydroxyestradiol (57% difference, ≥4 cups/day vs. ≤6 cups/week; Ptrend = 0.001) and 2-hydroxyestrone (52% difference; Ptrend = 0.001), and several ratio measures. Decaffeinated coffee was not associated with 2-pathway metabolism, but women in the highest (vs. lowest) category of intake (≥2 cups/day vs. ≤1-3 cups/month) had significantly lower levels of two 16-pathway metabolites, estriol (25% difference; Ptrend = 0.01) and 17-epiestriol (48% difference; Ptrend = 0.0004). Tea intake was positively associated with 17-epiestriol (52% difference; Ptrend = 0.01).
  
  
  CONCLUSIONS
  Caffeine and coffee intake were both associated with profiles of estrogen metabolism in premenopausal women.
  
  
  CONCLUSIONS
  Consumption of caffeine and coffee may alter patterns of premenopausal estrogen metabolism.
authors.affiliation: Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, Massachusetts. jss235@mail.harvard.edu.
authors.forename: Julia S
authors.initials: JS
authors.lastname: Sisti
authors.affiliation: Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, Massachusetts. Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts. Department of Biostatistics and Epidemiology, School of Public Health and Health Sciences, University of Massachusetts, Amherst, Massachusetts.
authors.forename: Susan E
authors.initials: SE
authors.lastname: Hankinson
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland.
authors.forename: Neil E
authors.initials: NE
authors.lastname: Caporaso
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland.
authors.forename: Fangyi
authors.initials: F
authors.lastname: Gu
authors.affiliation: Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, Massachusetts. Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: Rulla M
authors.initials: RM
authors.lastname: Tamimi
authors.affiliation: Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: Bernard
authors.initials: B
authors.lastname: Rosner
authors.affiliation: Cancer Research Technology Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland.
authors.forename: Xia
authors.initials: X
authors.lastname: Xu
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, Bethesda, Maryland.
authors.forename: Regina
authors.initials: R
authors.lastname: Ziegler
authors.affiliation: Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, Massachusetts. Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: A Heather
authors.initials: AH
authors.lastname: Eliassen
mesh_terms: D000328:Adult; D002110:Caffeine / Q000737:chemistry*; D002853:Chromatography, Liquid / Q000379:methods*; D003069:Coffee / Q000737:chemistry*; D015331:Cohort Studies; D004967:Estrogens / Q000652:urine*; D005260:Female; D006801:Humans; D008875:Middle Aged; D017697:Premenopause / Q000652:urine*; D011446:Prospective Studies; D053719:Tandem Mass Spectrometry / Q000379:methods*; D013662:Tea / Q000737:chemistry*
chemical_list: D003069:Coffee; D004967:Estrogens; D013662:Tea; D002110:Caffeine