title: Enhanced bone metabolism in vegetarians--the role of vitamin B12 deficiency.
abstract: BACKGROUND
  Vitamin B12 deficiency and bone fractures are common in vegetarians. However, a direct relationship between vitamin B12 status and bone metabolism in vegetarians has not been tested sufficiently.
  
  
  METHODS
  Our study included 96 vegetarians (23 German vegans, and 54 German and 19 Indian lacto-, lacto-ovo-vegetarians) and 89 omnivores (Germans and Asian-Indian immigrants in Oman). Blood concentrations of total vitamin B12, holotranscobalamin (holoTC), 25OH-vitamin D (25(OH)D), total homocysteine (tHcy), methylmalonic acid (MMA), and the bone turnover markers (BTMs) bone alkaline phosphatase (BAP), osteocalcin (OC), pro-collagen type I N-terminal peptide (PINP) and C-terminal telopeptides of collagen I (CTx) were measured.
  
  
  RESULTS
  Vegetarians from both population groups exhibited significantly higher concentrations of tHcy, MMA, folate, and BAP, but lower concentrations of holoTC and cobalamin compared with omnivores from the same population. Additionally, German vegetarians had higher circulating activities of BAP as well as higher CTx, OC, and PINP compared with their omnivorous controls. HoloTC and MMA were correlated with OC, CTx and BAP. Subjects with low vitamin B12 status (holoTC < or =35 pmol/L and MMA >271 nmol/L) had significantly lower serum concentrations of 25(OH)D, but higher tHcy and the BTMs P1NP, BAP, OC, and CTx, compared with subjects with normal vitamin B12 status. Multiple regression analysis showed that the association between BTMs and markers of vitamin B12 status was independent from the association with 25(OH)D. Approximately 12%-14% of the variation in the concentration of BTMs was explained by a regression model including holoTC, MMA and 25(OH)D. The strictness of the diet was not related to the magnitude of change in BTMs.
  
  
  CONCLUSIONS
  Low vitamin B12 status is related to increased bone turnover in vegetarians which is independent from vitamin D status.
authors.affiliation: Department of Clinical Chemistry and Laboratory Medicine/Central Laboratory, University Hospital, Saarland University, Homburg/Saar, Germany. kchwher@uks.eu
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Herrmann
authors.forename: Rima
authors.initials: R
authors.lastname: Obeid
authors.forename: Heike
authors.initials: H
authors.lastname: Schorr
authors.forename: Ulrich
authors.initials: U
authors.lastname: Hübner
authors.forename: Jürgen
authors.initials: J
authors.lastname: Geisel
authors.forename: Marga
authors.initials: M
authors.lastname: Sand-Hill
authors.forename: Nayyar
authors.initials: N
authors.lastname: Ali
authors.forename: Markus
authors.initials: M
authors.lastname: Herrmann
mesh_terms: D000328:Adult; D000368:Aged; D044466:Asian People; D015415:Biomarkers / Q000097:blood / Q000378:metabolism; D001842:Bone and Bones / Q000378:metabolism*; D014676:Diet, Vegetarian; D005858:Germany; D006801:Humans; D007194:India; D008875:Middle Aged; D014806:Vitamin B 12 Deficiency / Q000097:blood / Q000378:metabolism*
chemical_list: D015415:Biomarkers