title: Vitamin B-12 treatment of asymptomatic, deficient, elderly Chileans improves conductivity in myelinated peripheral nerves, but high serum folate impairs vitamin B-12 status response assessed by the combined indicator of vitamin B-12 status.
abstract: BACKGROUND
  It is uncertain whether vitamin B-12 supplementation can improve neurophysiologic function in asymptomatic elderly with low vitamin B-12 status or whether folate status affects responses to vitamin B-12 supplementation.
  
  
  OBJECTIVE
  We assessed the effects of a single intramuscular injection of 10 mg vitamin B-12 (which also contained 100 mg vitamin B-6 and 100 mg vitamin B-1) on vitamin B-12 status and neurophysiologic function in elderly community-dwelling Chileans with low serum vitamin B-12 concentrations who were consuming bread fortified with folic acid.
  
  
  METHODS
  A pretreatment and posttreatment study was conducted in 51 participants (median ± SD age: 73 ± 3 y; women: 47%) with serum vitamin B-12 concentrations <120 pmol/L at screening. Vitamin B-12 status was defined by combining vitamin B-12, plasma total homocysteine (tHcy), methylmalonic acid (MMA), and holotranscobalamin into one variable [combined indicator of vitamin B-12 status (cB-12)]. The response to treatment was assessed by measuring cB-12 and neurophysiologic variables at baseline and 4 mo after treatment.
  
  
  RESULTS
  Treatment increased serum vitamin B-12, holotranscobalamin, and cB-12 (P < 0.001) and reduced plasma tHcy and serum MMA (P < 0.001). Treatment produced consistent improvements in conduction in myelinated peripheral nerves; the sensory latency of both the left and right sural nerves improved on the basis of faster median conduction times of 3.1 and 3.0 ms and 3.3 and 3.4 ms, respectively (P < 0.0001). A total of 10 sensory potentials were newly observed in sural nerves after treatment. Participants with high serum folate at baseline (above the median, ≥33.9 nmol/L) had less improvement in cB-12 (P < 0.001) than did individuals whose serum folate was less than the median concentration (i.e., with a concentration <33.9 nmol/L).
  
  
  CONCLUSIONS
  Asymptomatic Chilean elderly with poor vitamin B-12 status displayed improved conductivity in myelinated peripheral nerves after vitamin B-12 treatment and an interaction with folate status, which was detected only with the use of cB-12. This trial was registered at www.controlled-trials.com as ISRCTN02694183.
authors.affiliation: USDA/Agricultural Research Service, Western Human Nutrition Research Center, Davis, CA;
authors.forename: Alex
authors.initials: A
authors.lastname: Brito
authors.affiliation: Department of Neurological Science, Faculty of Medicine, and.
authors.forename: Renato
authors.initials: R
authors.lastname: Verdugo
authors.affiliation: Institute of Nutrition and Food Technology, University of Chile, Santiago, Chile;
authors.forename: Eva
authors.initials: E
authors.lastname: Hertrampf
authors.affiliation: Department of Nutritional Sciences, Rutgers University, New Brunswick, NJ; Department of Pathology and Laboratory Medicine, University of California, Davis, CA; and.
authors.forename: Joshua W
authors.initials: JW
authors.lastname: Miller
authors.affiliation: Department of Pathology and Laboratory Medicine, University of California, Davis, CA; and.
authors.forename: Ralph
authors.initials: R
authors.lastname: Green
authors.affiliation: Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark.
authors.forename: Sergey N
authors.initials: SN
authors.lastname: Fedosov
authors.affiliation: USDA/Agricultural Research Service, Western Human Nutrition Research Center, Davis, CA;
authors.forename: Setareh
authors.initials: S
authors.lastname: Shahab-Ferdows
authors.affiliation: Institute of Nutrition and Food Technology, University of Chile, Santiago, Chile;
authors.forename: Hugo
authors.initials: H
authors.lastname: Sanchez
authors.affiliation: Institute of Nutrition and Food Technology, University of Chile, Santiago, Chile;
authors.forename: Cecilia
authors.initials: C
authors.lastname: Albala
authors.affiliation: Department of Neurological Science, Faculty of Medicine, and.
authors.forename: Jose L
authors.initials: JL
authors.lastname: Castillo
authors.affiliation: Department of Neurological Science, Faculty of Medicine, and.
authors.forename: Jose M
authors.initials: JM
authors.lastname: Matamala
authors.affiliation: Institute of Nutrition and Food Technology, University of Chile, Santiago, Chile;
authors.forename: Ricardo
authors.initials: R
authors.lastname: Uauy
authors.affiliation: USDA/Agricultural Research Service, Western Human Nutrition Research Center, Davis, CA; lindsay.allen@ars.usda.gov.
authors.forename: Lindsay H
authors.initials: LH
authors.lastname: Allen
mesh_terms: D000368:Aged; D002677:Chile; D019587:Dietary Supplements; D005260:Female; D005492:Folic Acid / Q000097:blood*; D005527:Food, Fortified; D006710:Homocysteine / Q000097:blood; D006801:Humans; D008297:Male; D008764:Methylmalonic Acid / Q000097:blood; D009413:Nerve Fibers, Myelinated / Q000187:drug effects* / Q000502:physiology; D009431:Neural Conduction / Q000187:drug effects*; D009752:Nutritional Status; D010525:Peripheral Nerves / Q000187:drug effects* / Q000502:physiology; D014805:Vitamin B 12 / Q000097:blood / Q000494:pharmacology / Q000627:therapeutic use; D014806:Vitamin B 12 Deficiency / Q000097:blood / Q000188:drug therapy*; D014803:Vitamin B Complex / Q000097:blood / Q000494:pharmacology / Q000627:therapeutic use
chemical_list: D006710:Homocysteine; D014803:Vitamin B Complex; D008764:Methylmalonic Acid; D005492:Folic Acid; D014805:Vitamin B 12
keywords: Chile; elderly; folate; folic acid fortification; holotranscobalamin; methylmalonic acid; nerve conductivity; total homocysteine; vitamin B-12