title: Dietary factors of one-carbon metabolism and prostate cancer risk.
abstract: BACKGROUND
  Folate is hypothesized to be inversely associated with the risk of several cancers, but such a potential association has not been well studied for prostate cancer. Vitamin B-6, vitamin B-12, methionine, and alcohol can influence folate-related metabolism.
  
  
  OBJECTIVE
  The objective was to investigate the associations between dietary factors of one-carbon metabolism and prostate cancer risk within the alpha-Tocopherol, beta-Carotene Cancer Prevention Study.
  
  
  METHODS
  Of the cohort's 27 111 Finnish male smokers aged 50-69 y who had complete dietary data, 1270 had a diagnosis of incident prostate cancer between 1985 and 2002. Folate, vitamin B-6, vitamin B-12, methionine, and alcohol intakes were estimated from a 276-item modified dietary history questionnaire. Cox proportional hazard models, adjusted for age and vitamin supplement use, estimated relative risks (RR) and 95% CIs.
  
  
  RESULTS
  Vitamin B-6 intake was inversely associated with prostate cancer risk (RR for highest versus lowest quintile: 0.88; 95% CI: 0.72, 1.07; P for trend = 0.045), whereas vitamin B-12 intake was associated with significantly increased risk (RR = 1.36; 95% CI: 1.14, 1.96; P for trend = 0.01). No association between folate or alcohol intake and prostate cancer risk was observed. No differences were found in the above associations according to stage of disease or subgroups of several potential effect modifiers.
  
  
  CONCLUSIONS
  We found no convincing evidence for a protective role of one-carbon metabolism against prostate cancer, although these observations can be generalized only to smokers. The possible modest protective association with vitamin B-6 and the significantly elevated risk with vitamin B-12 intake warrant further investigation.
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, MD, 20892, USA. weinstes@mail.nih.gov
authors.forename: Stephanie J
authors.initials: SJ
authors.lastname: Weinstein
authors.forename: Rachael
authors.initials: R
authors.lastname: Stolzenberg-Solomon
authors.forename: Pirjo
authors.initials: P
authors.lastname: Pietinen
authors.forename: Philip R
authors.initials: PR
authors.lastname: Taylor
authors.forename: Jarmo
authors.initials: J
authors.lastname: Virtamo
authors.forename: Demetrius
authors.initials: D
authors.lastname: Albanes
mesh_terms: D000368:Aged; D000428:Alcohol Drinking; D002244:Carbon / Q000378:metabolism*; D016022:Case-Control Studies; D019587:Dietary Supplements; D004311:Double-Blind Method; D000431:Ethanol / Q000008:administration & dosage; D005387:Finland / Q000453:epidemiology; D005492:Folic Acid / Q000008:administration & dosage; D006801:Humans; D008297:Male; D008715:Methionine / Q000008:administration & dosage; D008875:Middle Aged; D019875:One-Carbon Group Transferases / Q000378:metabolism; D016016:Proportional Hazards Models; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000139:chemically induced / Q000453:epidemiology* / Q000378:metabolism / Q000517:prevention & control*; D016032:Randomized Controlled Trials as Topic; D018570:Risk Assessment; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects; D014805:Vitamin B 12 / Q000008:administration & dosage / Q000009:adverse effects; D025101:Vitamin B 6 / Q000008:administration & dosage; D024502:alpha-Tocopherol / Q000008:administration & dosage; D019207:beta Carotene / Q000008:administration & dosage
chemical_list: D019207:beta Carotene; D000431:Ethanol; D002244:Carbon; D025101:Vitamin B 6; D005492:Folic Acid; D008715:Methionine; D019875:One-Carbon Group Transferases; D024502:alpha-Tocopherol; D014805:Vitamin B 12