title: Dietary intake of B vitamins and methionine and breast cancer risk.
abstract: OBJECTIVE
  We investigated prospectively the relationship between dietary intakes of methionine and B vitamins associated with one-carbon metabolism and breast cancer risk, including modification by age, hormone receptor status and alcohol consumption. Interactions between different B vitamins and methionine were also examined.
  
  
  METHODS
  During follow-up of 20,756 women from the Melbourne Collaborative Cohort Study for an average of 16 years, we ascertained 936 incident breast cancers. Dietary intakes were estimated using a 121-item food frequency questionnaire. Hazard ratios (HR) and 95 % confidence intervals were estimated using Cox regression.
  
  
  RESULTS
  We found weak evidence for an inverse association between breast cancer risk and riboflavin intake (fourth versus first quartile, HR Q4 vs. Q1 = 0.84 (0.69, 1.01); p linear trend = 0.05) and a positive association for vitamin B12 (HR Q4 vs. Q1 = 1.21 (1.00, 1.46); p linear trend = 0.06). We did not find any significant interactions between alcohol consumption and any of the B vitamins or methionine intake (all p interaction > 0.17) or between methionine or folate intake and any other B vitamins (all p interaction > 0.07). No association varied by tumor hormone receptor status (all p homogeneity > 0.14).
  
  
  CONCLUSIONS
  We found weak evidence of an inverse association between breast cancer risk and riboflavin intake and a positive association with vitamin B12.
authors.affiliation: Cancer Epidemiology Centre, Cancer Council Victoria, 1 Rathdowne Street, Carlton, VIC, 3053, Australia. julie.bassett@cancervic.org.au
authors.forename: Julie K
authors.initials: JK
authors.lastname: Bassett
authors.forename: Laura
authors.initials: L
authors.lastname: Baglietto
authors.forename: Allison M
authors.initials: AM
authors.lastname: Hodge
authors.forename: Gianluca
authors.initials: G
authors.lastname: Severi
authors.forename: John L
authors.initials: JL
authors.lastname: Hopper
authors.forename: Dallas R
authors.initials: DR
authors.lastname: English
authors.forename: Graham G
authors.initials: GG
authors.lastname: Giles
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001315:Australia / Q000453:epidemiology; D001943:Breast Neoplasms / Q000453:epidemiology / Q000209:etiology* / Q000517:prevention & control*; D019587:Dietary Supplements; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008715:Methionine / Q000008:administration & dosage*; D008875:Middle Aged; D011379:Prognosis; D011446:Prospective Studies; D012307:Risk Factors; D014803:Vitamin B Complex / Q000008:administration & dosage*
chemical_list: D014803:Vitamin B Complex; D008715:Methionine