title: Urinary 3,3'-diindolylmethane: a biomarker of glucobrassicin exposure and indole-3-carbinol uptake in humans.
abstract: BACKGROUND
  Brassica vegetable consumption may confer a protective effect against cancer, possibly attributable to their glucosinolates. Glucobrassicin is a predominant glucosinolate and is the precursor of indole-3-carbinol (I3C), a compound with anticancer effects. However, objective assessments of I3C uptake from Brassica vegetables have not been successful.
  
  
  METHODS
  We conducted a randomized, crossover trial to test whether 3,3'-diindolylmethane (DIM, a metabolite of I3C) excreted in the urine after consumption of raw Brassica vegetables with divergent glucobrassicin concentrations is a marker of I3C uptake from such foods. Twenty-five subjects were fed 50 g of either raw "Jade Cross" Brussels sprouts (high glucobrassicin concentration) or "Blue Dynasty" cabbage (low glucobrassicin concentration) once daily for 3 days. All urine was collected for 24 hours after vegetable consumption each day. After a washout period, subjects crossed over to the alternate vegetable. Urinary DIM was measured using a novel liquid chromatography-electrospray ionization-tandem mass spectrometry-selected reaction monitoring (LC-ESI-MS/MS-SRM) method with [(2)H2]DIM as internal standard.
  
  
  RESULTS
  Urinary DIM was consistently and significantly higher after Brussels sprouts feeding than after cabbage feeding, as evidenced by an average difference of 8.73 pmol/mg creatinine (95% confidence interval, 5.36-12.10; P = 0.00002).
  
  
  CONCLUSIONS
  We have successfully quantified urinary DIM after uptake of I3C from food, and demonstrated that differences in glucobrassicin exposure are reflected in urinary DIM levels.
  
  
  CONCLUSIONS
  Our LC-ESI-MS/MS-SRM method and the results of our study indicate urinary DIM is a measure of I3C uptake from Brassica vegetables, a finding that can be utilized in prospective epidemiologic and chemoprevention studies.
authors.affiliation: Authors' Affiliations: Divisions of Hematology, Oncology, and Transplantation and Epidemiology and Community Health; Masonic Cancer Center, and Departments of Urology and Psychiatry, University of Minnesota, Minneapolis; Departments of Food Science and Nutrition and Horticultural Science, University of Minnesota, St. Paul; and Southern Research and Outreach Center, University of Minnesota, Waseca, Minnesota.
authors.forename: Naomi
authors.initials: N
authors.lastname: Fujioka
authors.forename: Cheryl E
authors.initials: CE
authors.lastname: Ainslie-Waldman
authors.forename: Pramod
authors.initials: P
authors.lastname: Upadhyaya
authors.forename: Steven G
authors.initials: SG
authors.lastname: Carmella
authors.forename: Vincent A
authors.initials: VA
authors.lastname: Fritz
authors.forename: Charles
authors.initials: C
authors.lastname: Rohwer
authors.forename: Yunhua
authors.initials: Y
authors.lastname: Fan
authors.forename: Diane
authors.initials: D
authors.lastname: Rauch
authors.forename: Chap
authors.initials: C
authors.lastname: Le
authors.forename: Dorothy K
authors.initials: DK
authors.lastname: Hatsukami
authors.forename: Stephen S
authors.initials: SS
authors.lastname: Hecht
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000652:urine; D001937:Brassica; D018592:Cross-Over Studies; D005260:Female; D005961:Glucosinolates / Q000008:administration & dosage* / Q000493:pharmacokinetics; D006801:Humans; D007211:Indoles / Q000008:administration & dosage* / Q000493:pharmacokinetics* / Q000652:urine*; D008297:Male; D008875:Middle Aged; D053719:Tandem Mass Spectrometry; D055815:Young Adult
chemical_list: D015415:Biomarkers; D005961:Glucosinolates; D007211:Indoles; C016517:indole-3-carbinol; C048308:glucobrassicin; C016392:3,3'-diindolylmethane