title: A dose-response meta-analysis reveals an association between vitamin B12 and colorectal cancer risk.
abstract: The current meta-analysis evaluated the association between vitamin B12 intake and blood vitamin B12 level and colorectal cancer (CRC) risk.
  
  
  
  The PubMed and EMBASE databases were searched. A dose-response analysis was performed with generalized least squares regression, with the relative risk (RR) and 95 % CI as effect values.
  
  
  
  The meta-analysis included seventeen studies.
  
  
  
  A total of 10 601 patients.
  
  
  
  The non-linear dose-response relationship between total vitamin B12 intake and CRC risk was insignificant (P=0·690), but the relationship between dietary vitamin B12 intake and CRC risk was significant (P<0·001). Every 4·5 μg/d increment in total and dietary vitamin B12 intake was inversely associated with CRC risk (total intake: RR=0·963; 95 % CI 0·928, 0·999; dietary intake: RR=0·914; 95 % CI 0·856, 0·977). The inverse association between vitamin B12 intake and CRC risk was also significant when vitamin B12 intake was over a dosage threshold, enhancing the non-linear relationship. The non-linear dose-response relationship between blood vitamin B12 level and CRC risk was insignificant (P=0·219). There was an insignificant association between every 150 pmol/l increment in blood vitamin B12 level and CRC risk (RR=1·023; 95 % CI 0·881, 1·187).
  
  
  
  Our meta-analysis indicates that evidence supports the use of vitamin B12 for cancer prevention, especially among populations with high-dose vitamin B12 intake, and that the association between CRC risk and total vitamin B12 intake is stronger than between CRC risk and dietary vitamin B12 intake only.
authors.affiliation: 1Department of Anesthesiology,First Hospital of China Medical University,Heping District,Shenyang City,People's Republic of China.
authors.forename: Nai-Hui
authors.initials: NH
authors.lastname: Sun
authors.affiliation: 2Department of Surgical Oncology and General Surgery,First Hospital of China Medical University,155 North Nanjing Street,Heping District,Shenyang City 110001,People's Republic of China.
authors.forename: Xuan-Zhang
authors.initials: XZ
authors.lastname: Huang
authors.affiliation: 3Administration Section of the Party and Government Office of China Medical University,Shenyang City,People's Republic of China.
authors.forename: Shuai-Bo
authors.initials: SB
authors.lastname: Wang
authors.affiliation: 2Department of Surgical Oncology and General Surgery,First Hospital of China Medical University,155 North Nanjing Street,Heping District,Shenyang City 110001,People's Republic of China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Li
authors.affiliation: 2Department of Surgical Oncology and General Surgery,First Hospital of China Medical University,155 North Nanjing Street,Heping District,Shenyang City 110001,People's Republic of China.
authors.forename: Long-Yi
authors.initials: LY
authors.lastname: Wang
authors.affiliation: 2Department of Surgical Oncology and General Surgery,First Hospital of China Medical University,155 North Nanjing Street,Heping District,Shenyang City 110001,People's Republic of China.
authors.forename: Hong-Chi
authors.initials: HC
authors.lastname: Wang
authors.affiliation: 2Department of Surgical Oncology and General Surgery,First Hospital of China Medical University,155 North Nanjing Street,Heping District,Shenyang City 110001,People's Republic of China.
authors.forename: Chang-Wang
authors.initials: CW
authors.lastname: Zhang
authors.affiliation: 2Department of Surgical Oncology and General Surgery,First Hospital of China Medical University,155 North Nanjing Street,Heping District,Shenyang City 110001,People's Republic of China.
authors.forename: Cong
authors.initials: C
authors.lastname: Zhang
authors.affiliation: 2Department of Surgical Oncology and General Surgery,First Hospital of China Medical University,155 North Nanjing Street,Heping District,Shenyang City 110001,People's Republic of China.
authors.forename: Hong-Peng
authors.initials: HP
authors.lastname: Liu
authors.affiliation: 2Department of Surgical Oncology and General Surgery,First Hospital of China Medical University,155 North Nanjing Street,Heping District,Shenyang City 110001,People's Republic of China.
authors.forename: Zhen-Ning
authors.initials: ZN
authors.lastname: Wang
mesh_terms: D015179:Colorectal Neoplasms / Q000453:epidemiology*; D004032:Diet; D006801:Humans; D012307:Risk Factors; D014805:Vitamin B 12 / Q000008:administration & dosage* / Q000097:blood*
chemical_list: D014805:Vitamin B 12
keywords: Colorectal cancer; Meta-analysis; Vitamin B12