title: Choline and betaine intake and risk of breast cancer among post-menopausal women.
abstract: BACKGROUND
  Choline and betaine, similar to folate, are nutrients involved in one-carbon metabolism and hypothesised to reduce breast cancer risk. No prospective study among post-menopausal women has examined choline and betaine intakes in relation to breast cancer risk.
  
  
  METHODS
  We examined the intake of choline and betaine and breast cancer risk among 74 584 post-menopausal women in the Nurses' Health Study. Nutrient intake was assessed using a validated food-frequency questionnaire six times since 1984. During 20 years of follow-up from 1984 until 2004, we documented 3990 incident cases of invasive breast cancer.
  
  
  RESULTS
  Overall, choline (mean+/-s.d.; 326+/-61 mg per day) and betaine (104+/-33 mg per day) intake was not associated with a reduced risk of post-menopausal breast cancer. Participants in the highest quintile of intakes had multivariate relative risks of 1.10 (95% confidence interval (95% CI): 0.99-1.22; P-value, test for trend=0.14) for choline and 0.98 (95% CI: 0.89-1.09; P-value, test for trend=0.96) for betaine, compared with those in the lowest quintiles of intakes. The results were similar in breast cancer stratified by hormone receptor (oestrogen receptor/progesterone receptor) status. The association between choline intake and breast cancer risk did not differ appreciably by alcohol intake (non-drinker, <15 or 15+ g per day) or several other breast cancer risk factors, including family history of breast cancer, history of benign breast disease, body mass index, post-menopausal hormone use, and folate intake.
  
  
  CONCLUSIONS
  We found no evidence that higher intakes of choline and betaine reduce risk of breast cancer among post-menopausal women.
authors.affiliation: Channing Laboratory, Department of Medicine, Harvard Medical School and Brigham and Women's Hospital, Boston, MA 02115, USA. eunyoung.cho@channing.harvard.edu
authors.forename: E
authors.initials: E
authors.lastname: Cho
authors.forename: M D
authors.initials: MD
authors.lastname: Holmes
authors.forename: S E
authors.initials: SE
authors.lastname: Hankinson
authors.forename: W C
authors.initials: WC
authors.lastname: Willett
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001622:Betaine / Q000008:administration & dosage*; D001943:Breast Neoplasms / Q000209:etiology*; D002794:Choline / Q000008:administration & dosage*; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage; D006801:Humans; D008875:Middle Aged; D017698:Postmenopause; D011446:Prospective Studies; D011960:Receptors, Estrogen / Q000032:analysis; D011980:Receptors, Progesterone / Q000032:analysis; D012306:Risk
chemical_list: D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D001622:Betaine; D005492:Folic Acid; D002794:Choline