title: Association of homocysteine, vitamin B12, and folate with bone mineral density in postmenopausal women: a meta-analysis.
abstract: BACKGROUND
  The relationship of homocysteine (Hcy), folate, and vitamin B12 with bone mineral density (BMD) has been investigated in postmenopausal women. However, the relationship is still controversial.
  
  
  OBJECTIVE
  To evaluate the association of Hcy, folate, vitamin B12 and BMD in postmenopausal women with a meta-analysis.
  
  
  METHODS
  We searched for all published articles indexed in Medline (1950-2012), Embase (1974-2012), and China National Knowledge Infrastructure (1994-2012). Any case-control or cohort study relating to Hcy, vitamin B12, folate, and BMD was included, and the data were extracted independently by two reviewers. Criteria for inclusion were the assessment of Hcy, vitamin B12, folate, and BMD in postmenopausal women as outcomes. We performed this meta-analysis with Review Manager 5.1 software. Odds ratios and 95 % confidence intervals (CI) were used to evaluate the results.
  
  
  RESULTS
  Six eligible studies were selected for meta-analysis. Our analysis suggested that vitamin B12 and Hcy levels were significantly higher in postmenopausal osteoporosis (PMOP) group than that in controls (P = 0.007, <0.05; 95 % CI 3.06-19.38 and P = 0.0003, <0.05; 95 % CI 0.75-2.52, respectively). Folate level was lower in PMOP group than that in controls, but this difference was not statistically significant (P = 0.09, 95 % CI -3.33 to 0.25).
  
  
  CONCLUSIONS
  Hcy and vitamin B12, but not folate, were related to BMD in PMOP. Extra vitamin B12 may not play a protective role for osteoporosis in postmenopausal women. Future studies are needed to confirm them, especially the relationship between increased vitamin B12 and BMD.
authors.affiliation: Department of Obstetrics and Gynecology, The First Affiliated Hospital of Nanjing Medical University, 300 Guangzhou Road, 210029, Nanjing, China.
authors.forename: Hongxiu
authors.initials: H
authors.lastname: Zhang
authors.forename: Xincheng
authors.initials: X
authors.lastname: Tao
authors.forename: Jie
authors.initials: J
authors.lastname: Wu
mesh_terms: D015519:Bone Density; D016022:Case-Control Studies; D002681:China; D015331:Cohort Studies; D016001:Confidence Intervals; D005260:Female; D005492:Folic Acid / Q000097:blood*; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000097:blood; D017698:Postmenopause / Q000097:blood*; D014805:Vitamin B 12 / Q000097:blood*
chemical_list: D006710:Homocysteine; D005492:Folic Acid; D014805:Vitamin B 12