title: Metabolic evidence of vitamin B-12 deficiency, including high homocysteine and methylmalonic acid and low holotranscobalamin, is more pronounced in older adults with elevated plasma folate.
abstract: BACKGROUND
  An analysis of data from the National Health and Nutrition Examination Survey indicated that in older adults exposed to folic acid fortification, the combination of low serum vitamin B-12 and elevated folate is associated with higher concentrations of homocysteine and methylmalonic acid and higher odds ratios for cognitive impairment and anemia than the combination of low vitamin B-12 and nonelevated folate. These findings await confirmation in other populations.
  
  
  OBJECTIVE
  The purpose was to compare metabolic indicators of vitamin B-12 status, cognitive function, and depressive symptoms among elderly Latinos with elevated and nonelevated plasma folate.
  
  
  METHODS
  Cross-sectional data were analyzed for 1535 subjects (age: >or=60 y) from the Sacramento Area Latino Study on Aging. Subjects were divided into 4 groups on the basis of plasma vitamin B-12 (< or >or=148 pmol/L) and folate (<or= or >45.3 nmol/L). Homocysteine, methylmalonic acid, holotranscobalamin, ratio of holotranscobalamin to vitamin B-12, Modified Mini-Mental State Examination, delayed recall, and depressive symptom scores were compared between the groups.
  
  
  RESULTS
  Individuals with low vitamin B-12 and elevated folate (n = 22) had the highest concentrations of homocysteine and methylmalonic acid and the lowest concentration of holotranscobalamin and ratio of holotranscobalamin to vitamin B-12 when compared with all other groups (P <or= 0.003). No differences in Modified Mini-Mental State Examination, delayed recall, and depressive symptom scores were observed between the low vitamin B-12 and elevated-folate group compared with other groups.
  
  
  CONCLUSIONS
  Low vitamin B-12 is associated with more pronounced metabolic evidence of vitamin B-12 deficiency when folate is elevated than when folate is not elevated. These data should be considered when assessing the potential costs, risks, and benefits of folic acid and vitamin B-12 fortification programs.
authors.affiliation: School of Medicine, Department of Medical Pathology and Laboratory Medicine, University of California, Davis, CA, USA.
authors.forename: Joshua W
authors.initials: JW
authors.lastname: Miller
authors.forename: Marjorie G
authors.initials: MG
authors.lastname: Garrod
authors.forename: Lindsay H
authors.initials: LH
authors.lastname: Allen
authors.forename: Mary N
authors.initials: MN
authors.lastname: Haan
authors.forename: Ralph
authors.initials: R
authors.lastname: Green
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D005260:Female; D005492:Folic Acid / Q000097:blood*; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D008297:Male; D008764:Methylmalonic Acid / Q000097:blood*; D008875:Middle Aged; D014155:Transcobalamins / Q000032:analysis*; D014806:Vitamin B 12 Deficiency / Q000097:blood*
chemical_list: D014155:Transcobalamins; D006710:Homocysteine; D008764:Methylmalonic Acid; D005492:Folic Acid