title: Serum betaine but not choline is inversely associated with breast cancer risk: a case-control study in China.
abstract: OBJECTIVE
  Choline and betaine are important for DNA methylation and synthesis, and may affect tumor carcinogenesis. To our knowledge, no previous study has examined the association between serum choline and betaine and breast cancer risk. This study aimed to examine whether serum choline and betaine were inversely associated with breast cancer risk among Chinese women.
  
  
  METHODS
  This hospital-based case-control study consecutively recruited 510 breast cancer cases and 518 frequency-matched (age and residence) controls, and blood samples were available for 500 cases and 500 controls. Serum choline and betaine were assayed by high-performance liquid chromatography-tandem mass spectrometry. Multiple unconditional logistic regression was used to estimate odds ratios (ORs) and 95 % confidence intervals (CIs).
  
  
  RESULTS
  An inverse association with breast cancer risk was observed for serum betaine (fourth vs first quartile adjusted OR 0.68, 95 % CI 0.47-0.97) and for the ratio of serum betaine to choline (fourth vs first quartile adjusted OR 0.70, 95 % CI 0.48-1.00), but not for serum choline (fourth vs first quartile adjusted OR 0.80, 95 % CI 0.56-1.15). Serum betaine was inversely associated with breast cancer risk in subjects with below-median dietary folate intake (fourth vs first quartile adjusted OR 0.48, 95 % CI 0.30-0.77).
  
  
  CONCLUSIONS
  This study suggested that serum betaine but not choline was inversely associated with breast cancer risk. This result needed to be further confirmed by the prospective studies.
authors.affiliation: Department of Medical Statistics and Epidemiology, School of Public Health, Sun Yat-sen University, 74 Zhongshan Road 2, Guangzhou, 510080, China.
authors.forename: Yu-Feng
authors.initials: YF
authors.lastname: Du
authors.affiliation: Nursing Department, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, 510080, China.
authors.forename: Fang-Yu
authors.initials: FY
authors.lastname: Lin
authors.affiliation: Department of Clinical Laboratory, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, 510080, China.
authors.forename: Wei-Qing
authors.initials: WQ
authors.lastname: Long
authors.affiliation: Department of Medical Statistics and Epidemiology, School of Public Health, Sun Yat-sen University, 74 Zhongshan Road 2, Guangzhou, 510080, China.
authors.forename: Wei-Ping
authors.initials: WP
authors.lastname: Luo
authors.affiliation: Department of Medical Statistics and Epidemiology, School of Public Health, Sun Yat-sen University, 74 Zhongshan Road 2, Guangzhou, 510080, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Yan
authors.affiliation: Department of Medical Statistics and Epidemiology, School of Public Health, Sun Yat-sen University, 74 Zhongshan Road 2, Guangzhou, 510080, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Xu
authors.affiliation: Department of Vascular Surgery, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, 510080, China.
authors.forename: Xiong-Fei
authors.initials: XF
authors.lastname: Mo
authors.affiliation: Department of Medical Statistics and Epidemiology, School of Public Health, Sun Yat-sen University, 74 Zhongshan Road 2, Guangzhou, 510080, China. zhangcx3@mail.sysu.edu.cn.
authors.forename: Cai-Xia
authors.initials: CX
authors.lastname: Zhang
mesh_terms: D000328:Adult; D000368:Aged; D001622:Betaine / Q000097:blood*; D001943:Breast Neoplasms / Q000097:blood* / Q000453:epidemiology; D016022:Case-Control Studies; D002681:China; D002794:Choline / Q000097:blood*; D004032:Diet; D015444:Exercise; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage / Q000097:blood; D006801:Humans; D016015:Logistic Models; D008875:Middle Aged; D009752:Nutritional Status; D012307:Risk Factors; D012959:Socioeconomic Factors
chemical_list: D001622:Betaine; D005492:Folic Acid; D002794:Choline
keywords: Breast cancer risk; Case–control study; Serum betaine; Serum choline