title: B vitamin intakes and incidence of colorectal cancer: results from the Women's Health Initiative Observational Study cohort.
abstract: BACKGROUND
  The role of one-carbon metabolism nutrients in colorectal carcinogenesis is not fully understood. Associations might be modified by mandated folic acid (FA) fortification or alcohol intake.
  
  
  OBJECTIVE
  We investigated associations between intakes of folate, riboflavin, vitamin B-6, and vitamin B-12 and colorectal cancer (CRC) in the Women's Health Initiative Observational Study, stratified by time exposed to FA fortification and alcohol intake.
  
  
  METHODS
  A total of 88,045 postmenopausal women were recruited during 1993-1998; 1003 incident CRC cases were ascertained as of 2009. Quartiles of dietary intakes were compared; HRs and 95% CIs were estimated by Cox proportional hazards models.
  
  
  RESULTS
  Dietary and total intakes of vitamin B-6 in quartile 4 compared with quartile 1 (HR: 0.80; 95% CI: 0.66, 0.97 and HR: 0.80; 95% CI: 0.66, 0.99, respectively) and total intakes of riboflavin (HR: 0.81; 95% CI: 0.66, 0.99) were associated with reduced risk of CRC overall and of regionally spread disease. In current drinkers who consumed <1 drink (13 g alcohol)/wk, B vitamin intakes were inversely associated with CRC risk (P-interaction < 0.05). Dietary folate intake was positively associated with CRC risk among women who had experienced the initiation of FA fortification for 3 to <9 y (P-interaction < 0.01).
  
  
  CONCLUSIONS
  Vitamin B-6 and riboflavin intakes from diet and supplements were associated with a decreased risk of CRC in postmenopausal women. Associations of B vitamin intake were particularly strong for regional disease and among women drinkers who consumed alcohol infrequently. Our study provides new evidence that the increased folate intake during the early postfortification period may have been associated with a transient increase in CRC risk.
authors.affiliation: Division of Preventive Oncology, National Center for Tumor Diseases, Heidelberg, Germany.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Zschäbitz
authors.forename: Ting-Yuan David
authors.initials: TY
authors.lastname: Cheng
authors.forename: Marian L
authors.initials: ML
authors.lastname: Neuhouser
authors.forename: Yingye
authors.initials: Y
authors.lastname: Zheng
authors.forename: Roberta M
authors.initials: RM
authors.lastname: Ray
authors.forename: Joshua W
authors.initials: JW
authors.lastname: Miller
authors.forename: Xiaoling
authors.initials: X
authors.lastname: Song
authors.forename: David R
authors.initials: DR
authors.lastname: Maneval
authors.forename: Shirley A A
authors.initials: SA
authors.lastname: Beresford
authors.forename: Dorothy
authors.initials: D
authors.lastname: Lane
authors.forename: James M
authors.initials: JM
authors.lastname: Shikany
authors.forename: Cornelia M
authors.initials: CM
authors.lastname: Ulrich
mesh_terms: D000368:Aged; D000428:Alcohol Drinking / Q000009:adverse effects; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control; D004032:Diet / Q000009:adverse effects; D019587:Dietary Supplements; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use; D005500:Follow-Up Studies; D005527:Food, Fortified / Q000009:adverse effects; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012256:Riboflavin / Q000008:administration & dosage / Q000627:therapeutic use; D014481:United States / Q000453:epidemiology; D025101:Vitamin B 6 / Q000008:administration & dosage / Q000627:therapeutic use; D014803:Vitamin B Complex / Q000008:administration & dosage* / Q000009:adverse effects / Q000627:therapeutic use; D014804:Vitamin B Deficiency / Q000209:etiology / Q000503:physiopathology
chemical_list: D014803:Vitamin B Complex; D025101:Vitamin B 6; D005492:Folic Acid; D012256:Riboflavin