Cobalamin, Microbiota and Epigenetics

Living reference work entry


Functional cobalamin (B12) status and assessment are inextricably intertwined with the human microbiome. Small bowel bacterial overgrowth can both cause and result from gastritis and alter dietary cobalamin absorption. Some bacterial species may produce human-inaccessible cobalamin corrinoids and may create competition for human-accessible cobalamin. Increased human-inaccessible corrinoids from bacterial production may raise the total corrinoid level assessed by the serum total cobalamin, limiting diagnostic utility and masking a deficiency of human-accessible cobalamin. Anaerobic bacteria may reverse the propionic to succinic acid pathway, converting methylmalonic acid back to propionic acid to release CO2; this could raise propionic acid and lower methylmalonic acid levels, limiting its diagnostic utility. Cobalamin deficiency limits enzymatic conversion of homocysteine to methionine and increases homocysteine levels. Increased homocysteine can be reduced by diversion into the transsulfuration pathway, limiting the diagnostic power of this metabolite. Finally, in the delicate balance between folate and cobalamin which regulates DNA synthesis, excess synthetic folate from public health policies can combine with bacterial folate production to mask the macrocytic anemia of cobalamin deficiency.

Small bowel bacterial overgrowth can increase propionic acid production and reduce cobalamin bioavailability. Both propionic acid administration and cobalamin deficiency can alter brain fatty acid levels and brain function and cause autistic symptomology. Essential fatty acid ratios can modify gut bacterial species which can, in turn, modify fatty acid composition and inflammation. Omega-3 supplementation can reverse many of the symptoms of propionic acid neurotoxicity. Cobalamin supplementation can raise omega-3 fatty acid levels in the brain and can improve autism symptomology. Therefore, there are strong epigenetic interrelationships among cobalamin and its enzymatic activity, propionic acid, essential fatty acids, folate, and the human bacterial microbiome.


Autism spectrum disorder B12 Brain-derived neurotrophic factor Cobalamin Dysbiosis Methylation Methylmalonic acid Propionic acid Micronucleated lymphocytes Polyunsaturated fatty acid Short-chain fatty acids Small bowel bacterial overgrowth 

List of Abbreviations


Arachidonic acid


Attention deficit hyperactivity disorder


Autism spectrum disorder; B12 = cobalamin


Brain-derived neurotrophic factor


Docosahexaenoic acid


Eicosapentaenoic acid


Intrinsic factor


Methylmalonyl-CoA mutase




Methionine synthase


Methylmalonic acid


Micronucleated lymphocytes MTHF = methyltetrahydrofolate


Propionic acid


Polyunsaturated fatty acid






Short-chain fatty acids


Small bowel bacterial overgrowth




  1. Adams JB, Johansen LJ, Powell LD et al (2011a) Gastrointestinal flora and gastrointestinal status in children with autism – comparisons to typical children and correlation with autism severity. BMC Gastroenterol 11:22CrossRefPubMedPubMedCentralGoogle Scholar
  2. Adams JB, Audhya T, McDonough-Means S et al (2011b) Nutritional and metabolic status of children with autism vs. neurotypical children, and the association with autism severity. Nutr Metab (London) 8(34):1–32Google Scholar
  3. Agrawal S, Nathani S (2009) Neuro-regression in vitamin B12 deficiency. BMJ Cas Rep 2009:bcr06.2008.0235Google Scholar
  4. Al-Owain M, Kaya N, Al-Shamrani H et al (2013) Autism spectrum disorder in a child with propionic acidemia. JIMD Rep 7:63–66CrossRefPubMedGoogle Scholar
  5. Andersen AD, Molbak L, Michaelsen KF et al (2011) Molecular fingerprints of the human fecal microbiota from 9 to 18 months old and the effect of fish oil supplementation. J Pediatr Gastroenterol Nutr 53(3):303–309CrossRefPubMedGoogle Scholar
  6. Beard CM, Panser LA, Katusic SKI (2011) Folic acid supplementation a risk for autism? Med Hypoth 77(1):15–17CrossRefGoogle Scholar
  7. Belitsos PC, Greenson JK, Yardley JH et al (1992) Association of gastric hypoacidity with opportunistic enteric infections in patients with AIDS. J Infect Dis 166(2):277–284CrossRefPubMedGoogle Scholar
  8. Bennett M (2001) Vitamin B12 deficiency, infertility and fetal loss. J Reprod Med 46(3):209–212PubMedGoogle Scholar
  9. Brandt LJ, Berstein LH, Wagle A (1977) Production of vitamin B12 analogues in patients with small-bowel bacterial overgrowth. Ann Intern Med 87(5):546–551CrossRefPubMedGoogle Scholar
  10. Bredenoord AJ, Baron A, Smout AJPM (2006) Symptomatic gastro-oesophageal reflux in a patient with achlorhydria. Gut 55(7):1054–1055CrossRefPubMedPubMedCentralGoogle Scholar
  11. Brigandi SA, Shao H, Qian SY et al (2015) Autistic children exhibit decreased levels of essential fatty acids in red blood cells. Int J Mol Sci 16(5):10061–10076CrossRefPubMedPubMedCentralGoogle Scholar
  12. Chiang PK, Gordon RK, Tal J et al (1996) S-Adenosylmethionine and methylation. FASEB J 10:471–480PubMedGoogle Scholar
  13. Clonan A, Roberts KE, Holdsworth M (2016) Socioeconomic and demographic drivers of red and processed meat consumption: implications for health and environmental sustainability. Proc Nutr Soc 75(3):367–373CrossRefPubMedPubMedCentralGoogle Scholar
  14. Coppede F (2009) The complex relationship between folate/homocysteine metabolism and risk of down Syndrome. Mutat Res 682(1):54–70CrossRefPubMedGoogle Scholar
  15. Coppede F, Denaro M, Tannorella P, Migliore L (2016) Increased MTHFR promotor methylation in young mothers of down Syndrome individuals. Mutat Res 787:1–6CrossRefPubMedGoogle Scholar
  16. Daniel CR, Cross AJ, Koebnick C et al (2011) Trends in meat consumption in the United States. Public Health Nutr 14(4):575–583CrossRefPubMedGoogle Scholar
  17. Davis DJ, Hecht PM, Jasarevic E et al (2017) Sex-specific effects of docosahexaenoic acid (DHA) on the microbiome and behaviour of socially-isolated mice. Brain Behav Immun 59:38–48CrossRefPubMedGoogle Scholar
  18. Degnan PH, Taga ME, Goodman AL (2014) Vitamin B12 as a modulator of gut microbial ecology. Cell Metab 20(5):769–778CrossRefPubMedPubMedCentralGoogle Scholar
  19. DeSoto MC, Hitlan RT (2012) Synthetic folic acid supplementation during pregnancy may increase risk of developing autism. J Ped Biochemist 2(4):251–261Google Scholar
  20. Dhobale M, Joshi S (2012) Altered maternal micronutrients (folic acid, vitamin B12) and omega 3 fatty acids through oxidative stress may reduce neurotrophic factors in preterm pregnancy. J Matern Fetal Neonatal Med 25(4):317–325CrossRefPubMedGoogle Scholar
  21. Diav-Citrin O, Arnon J, Schectman S (2005) The safety of proton pump inhibitors in pregnancy: a multicenter prospective controlled study. Aliment Pharmacol Ther 21(3):269–275CrossRefPubMedGoogle Scholar
  22. Duran M, Ketting D, Wadman SK et al (1973) Propionic acid, an artifact which can leave methylmalonic acidemia undiscovered. Clinica Chemica Acta 49:177–179CrossRefGoogle Scholar
  23. El-Ansary A, Al-Ayadhi L (2014) Relative abundance of short chain and polyunsaturated fatty acids in propionic acid-induced autistic features in rat pups as potential markers in autism. Lipids Health Dis 13:140CrossRefPubMedPubMedCentralGoogle Scholar
  24. El-Ansary AK, Al-Daihan SK, El-Gezeery AR (2011) On the protective effect of omega-3 against propionic acid-induced neurotoxicity in rat pups. Lipids Health Dis 10:142CrossRefPubMedPubMedCentralGoogle Scholar
  25. Fenech MF, Dreosti IE, Rinaldi JR (1997) Folate, vitamin B12, homocysteine status and chromosome damage rate in lymphocytes of older men. Carcinogenesis 18(7):1329–1336CrossRefPubMedGoogle Scholar
  26. Fenech M, Aitken C, Rinaldi J (1998) Folate, vitamin B12, homocysteine status and DNA damage in young Australian adults. Carcinogenesis 19(7):1163–1171CrossRefPubMedGoogle Scholar
  27. Finegold SM, Dowd SE, Gontcharova V et al (2010) Pyrosequencing study of fecal microflora of autistic and control children. Anaerobe 16(4):444–453CrossRefPubMedGoogle Scholar
  28. Fischbach MA, Sonnenburg JL (2011) Eating for two: how metabolism establishes interspecies interactions in the gut. Cell Host Microbe 10(4):336–347CrossRefPubMedPubMedCentralGoogle Scholar
  29. Fitzgerald K, Hyman M, Swift K (2012) Autism Spectrum disorders. Glob Adv Health Med 1(4):62–74CrossRefPubMedPubMedCentralGoogle Scholar
  30. Frye RE, Rose S, Slattery J et al (2015) Gastrointestinal dysfunction in autism spectrum disorder: the role of the mitochondria and the enteric microbiome. Microb Ecol Health Dis 26:2748Google Scholar
  31. Fujimori S (2015) What are the effects of proton pump inhibitors on the small intestine? World J Gastroenterol 21(22):6817–6819CrossRefPubMedPubMedCentralGoogle Scholar
  32. Gadgil M, Joshi K, Pandit A et al (2014) Imbalance of folic acid and vitamin B12 is associated with birth outcome: an Indian pregnant women study. Eur J Clin Nutr 68(6):726–729CrossRefPubMedGoogle Scholar
  33. Ghosh S, Molcan E, DeCoffe D et al (2013) Diets rich in n-6 PUFA induce intestinal microbial dysbiosis in aged mice. Brit J Nutr 110(3):515–523CrossRefPubMedGoogle Scholar
  34. Gille D, Schmid A (2015) Vitamin B12 in meat and dairy products. Nutr Rev 73(2):106–115CrossRefPubMedGoogle Scholar
  35. Gillies D, Sinn JK, Lad SS et al (2012) Polyunsaturated fatty acids (PUFA) for attention deficit hyperactivity disorder (ADHD) in children and adolescents. Cochrane Database Syst Rev 7:CD007986Google Scholar
  36. Guez S, Chiarelli G, Menni F et al (2012) Severe vitamin B12 deficiency in an exclusively breastfed 5-month-old Italian infant born to a mother receiving multivitamin supplementation during pregnancy. BMC Pediatr 12:85CrossRefPubMedPubMedCentralGoogle Scholar
  37. Haboubi NY, Lee GS, Montgomery RD (1991) Duodenal mucosal morphometry of elderly patients with small intestinal bacterial overgrowth: response to antibiotic treatment. Age Ageing 20(1):29–32CrossRefPubMedGoogle Scholar
  38. Jerneren F, Elshorbagy AK, Oulhaj A (2015) Brain atrophy in cognitively impaired elderly: the importance of long-chain w-3 fatty acids and B vitamin status in a randomized controlled trial. Am J Clin Nutr 102(1):215–221CrossRefPubMedGoogle Scholar
  39. Kaliannan K, Wang B, Li X-Y et al (2015) A host-microbiome interaction mediates the opposing effects of omega-6 and omega-3 fatty acids on endotoxemia. Sci Rep 5:11276CrossRefPubMedPubMedCentralGoogle Scholar
  40. Kim SK, Kim YC (2005) Effects of betaine supplementation on hepatic metabolism of sulphur-containing amino acids in mice. J Hepatol 42(6):907–913CrossRefPubMedGoogle Scholar
  41. Klee GG (2000) Cobalamin and folate evaluation: measurement of methylmalonic acid and homocysteine vs vitamin B12 and folate. Clin Chem 46(8):1277–1283PubMedGoogle Scholar
  42. Kobe T, Witte AV, Schnelle A et al (2016) Vitamin B-12 concentration, memory performance, and hippocampal structure in patients with mild cognitive impairment. Am J Clin Nutr 103(4):1045–1054CrossRefPubMedGoogle Scholar
  43. Kocaoglu C, Akin F, Caksen H et al (2014) Cerebral atrophy in a vitamin B12-deficient infant of a vegetarian mother. J Health Popul Nutr 32(2):367–371PubMedPubMedCentralGoogle Scholar
  44. Krautler B (2012) Biochemistry of B12-cofactors in human metabolism. Subcell Biochem 56:323–346CrossRefPubMedGoogle Scholar
  45. Kulkarni A, Dangat K, Kale A et al (2011) Effects of altered maternal folic acid, vitamin B12 and docosahexaenoic acid on placental global DNA methylation patterns in Wistar rats. PLoS One 6(3):e17706CrossRefPubMedPubMedCentralGoogle Scholar
  46. Lappinga PJ, Abraham SC, Murray JA et al (2010) Small intestinal bacterial growth: histopathological features and clinical correlates in an underrecognized entity. Arch Pathol Lab Med 134(2):264–270PubMedGoogle Scholar
  47. LeBlanc JG, Milani C, de Giori GS et al (2013) Bacteria as vitamin suppliers to their host: a gut microbiota perspective. Curr Opin Biotechnol 24(2):160–168CrossRefPubMedGoogle Scholar
  48. Lebwohl B, Green PH, Genta RM (2015) The coeliac stomach: gastritis in patients with coeliac disease. Alimen Pharmaco Ther 42(2):180–187CrossRefGoogle Scholar
  49. Lewis SJ, Franco S, Young G et al (1996) Altered bowel function and duodenal bacterial overgrowth in patients treated with omeprazole. Aliment Pharmacol Ther 10(4):557–561Google Scholar
  50. Lindenbaum J, Savage DG, Stabler SP et al (1990) Diagnosis of cobalamin deficiency: II. Relative sensitivities of serum cobalamin, methylmalonic acid, and total homocysteine concentrations. Am J Hematol 34:99–107CrossRefPubMedGoogle Scholar
  51. Lovblad K, Ramelli G, Remonda L et al (1997) Retardation of myelination due to dietary B12 deficiency: cranial MRI findings. Pediatr Radiol 27(2):155–158CrossRefPubMedGoogle Scholar
  52. MacFabe DF (2012) Short-chain fatty acid fermentation products of the gut microbiome: implications in autism spectrum disorders. Microb Ecol Health Dis 23:1–24Google Scholar
  53. MacFabe DF, Cain DP, Rodriguez-Capote K et al (2007) Neurobiological effects of intraventricular propionic acid in rats: possible role of short chain fatty acids on the pathogenesis and characteristics of autism spectrum disorders. Behav Brain Res 176(1):149–169CrossRefPubMedGoogle Scholar
  54. MacFarlane AJ, Greene-Finestone LS, Shi Y (2011) Vitamin B-12 and homocysteine status in a folate-replete population: results from the Canadian health measures survey. Am J Clin Nutr 94(4):1079–1087CrossRefPubMedGoogle Scholar
  55. Main PA, Thomas P, Esterman A et al (2013) Necrosis is increased in lymphoblastoid cell lines from children with autism compared with their non-autistic siblings under conditions of oxidative and nitrosative stress. Mutagenesis 28(4):475–484CrossRefPubMedPubMedCentralGoogle Scholar
  56. Marcoullis G, Parmentier Y, Nicolas JP et al (1980) Cobalamin malabsorption due to nondegradation of R proteins in the human intestine. Inhibited cobalamin absorption in exocrine pancreatic dysfunction. J Clin Invest 66(3):430–440CrossRefPubMedPubMedCentralGoogle Scholar
  57. McKoll KE, el-Omar E, Gillen D (1998) Interactions between H. Pylori infection, gastric secretion and anti-secretory therapy. Mr Med Bull 54(1):121–138CrossRefGoogle Scholar
  58. Meyniel D, Petit J, Bodin F et al (1981) Vitamin B12 deficiency in chronic atrophic gastritis. 3 cases (author’s transl). Nouvelle Presse Med 10(27):2281–2284Google Scholar
  59. Molloy AM, Kirke PN, Troendle JF et al (2009) Maternal vitamin B12 status and risk of neural tube defects in a population with high neural tube defect prevalence and no folic acid fortification. Pediatrics 123(3):917–923CrossRefPubMedPubMedCentralGoogle Scholar
  60. Morita H, Toh H, Fukuda S et al (2008) Comparative genome analysis of lactobacillus reuteri and lactobacillus fermentum reveal a genomic island for reuterin and cobalamin production. DNA Res 15(3):151–161CrossRefPubMedPubMedCentralGoogle Scholar
  61. Morris MS, Jacques PF, Rosenberg IJ et al (2007) Folate and vitamin B-12 status in relation to anemia, macrocytosis, and cognitive impairment in older Americans in the age of folic acid fortification. Am J Clin Nutr 85(1):193–2000PubMedPubMedCentralGoogle Scholar
  62. Muyshondt E, Schwartz SI (1964) Vitamin B12 absorption following vagectomy and gastric surgery. Ann Surg 160(5):788–792CrossRefPubMedPubMedCentralGoogle Scholar
  63. Obeid R, Kasoha M, Kirsch SH et al (2010) Concentrations of unmetabolized folic acid and primary folate forms in pregnant women at delivery and in umbilical cord blood. Am J Clin Nutr 92(6):1416–1422CrossRefPubMedGoogle Scholar
  64. Parletta N, Niyonsenga T, Duff J (2016) Omega-3 and omega-6 polyunsaturated fatty acid levels and correlations with symptoms in children with attention deficit hyperactivity disorder, autistic spectrum disorder and typically developing controls. PLoS One 11(5):e0156432CrossRefPubMedPubMedCentralGoogle Scholar
  65. Pickell L, Brown K, Li D et al (2011) High intakes of folic acid disrupts embryonic development in mice. Birth Defects Res A Clin Mol Teratol 91(1):8–19CrossRefPubMedGoogle Scholar
  66. Rathod R, Khaire A, Kemse N et al (2014) Maternal omega-3 fatty acid supplementation on vitamin B12 rich diet improves brain omega-3 fatty acids, neurotrophins and cognition in the Wistar rat offspring. Brain Dev 36(10):853–863CrossRefPubMedGoogle Scholar
  67. Rathod RS, Khaire AA, Aa K et al (2016) Effect of vitamin B12 and omega-3 fatty acid supplementation on brain neurotrophins and cognition in rats: a multigeneration study. Biochimie 128–129:201–208CrossRefPubMedGoogle Scholar
  68. Ríos-Covián D, Ruas-Madiedo P, Margolles A et al (2016) Intestinal short chain fatty acids and their link with diet and human health. Front Microbiol 7:185CrossRefPubMedPubMedCentralGoogle Scholar
  69. Robertson RC, Seira Oriach C, Murphy K et al (2016) Omega-3 polyunsaturated fatty acids critically regulate behaviour and gut microbiota development in adolescence and adulthood. Brain Behav Immun 59:21–37CrossRefPubMedGoogle Scholar
  70. Rossi M, Amaretti A, Raimondi S (2011) Folate production by probiotic bacteria. Forum Nutr 3(1):118–134Google Scholar
  71. Roy S, Kale A, Dangat K et al (2012) Maternal micronutrients (folic acid and vitamin B12) and omega 3 fatty acids: implications for neurodevelopmental risk in the rat offspring. Brain and Development 34(1):64–71CrossRefPubMedGoogle Scholar
  72. Ruscin JM, Page RL 2nd, Valuck RJ (2002) Vitamin B(12) deficiency associated with histamine(2)-receptor antagonists and a proton-pump inhibitor. Ann Pharmacother 36(5):812–816CrossRefPubMedGoogle Scholar
  73. Sable P, Kale A, Joshi A et al (2014) Maternal micronutrient imbalance alters gene expression of BDNF, NGF, TrkB and CREB in the offspring at an adult age. Int J Dev Neurosci 34:24–32CrossRefPubMedGoogle Scholar
  74. Saltzman JR, Kemp JA, Golner BB et al (1994) Effect of hypochlorhydria due to omeprazole treatment or atrophic gastritis on protein-bound vitamin B12 absorption. J Am Coll Nutr 13(6):584–591CrossRefPubMedGoogle Scholar
  75. Schjonsby H (1989) Vitamin B12 absorption and malabsorption. Gut 30:1686–1691CrossRefPubMedPubMedCentralGoogle Scholar
  76. Sipponen P, Kekki M, Seppala K et al (1996) The relationships between chronic gastritis and gastric acid secretion. Aliment Pharmacol Ther 10(1):103–118CrossRefPubMedGoogle Scholar
  77. Smith CH, Israel DM, Schreiber R et al (2013) Proton pump inhibitors for irritable infants. Can Fam Physician 59(2):153–156PubMedPubMedCentralGoogle Scholar
  78. Song Y, Liu C, Finegold SM (2004) Real-time PCR quantitation of clostridia in feces of autistic children. Appl Environ Microbiol 70(11):6459–6465CrossRefPubMedPubMedCentralGoogle Scholar
  79. Stipanuk MH, Ueki I (2011) Dealing with methionine/homocysteine sulfur: cysteine metabolism to taurine and inorganic sulfur. J Inherit Metab Dis 34(1):17–32CrossRefPubMedGoogle Scholar
  80. Sugahara H, Odamaki T, Hashikura N et al (2015) Differences in folate production by bifidobacteria of different origins. Biosci Microbiota Food Health 34(4):87–93CrossRefPubMedPubMedCentralGoogle Scholar
  81. Suter PM, Golner BB, Goldin BR et al (1991) Reversal of protein-bound vitamin B12 malabsorption with antibiotics in atrophic gastritis. Gastroenterology 101(4):1039–1045CrossRefPubMedGoogle Scholar
  82. Takahashi-Iñiguez T, García-Hernandez E, Arreguín-Espinosa R et al (2012) Role of vitamin B12 on methylmalonyl-CoA mutase activity. J Zhejiang Univ Sci B 13(6):423–437CrossRefPubMedPubMedCentralGoogle Scholar
  83. Tam C, O’Connor D, Koren G (2012) Circulating unmetabolized folic acid: relationship to folate status and effect of supplementation. Obstet Gynecol Int 2012:485179CrossRefPubMedPubMedCentralGoogle Scholar
  84. Therrien A, Bouchard S, Sidani S et al (2016) Prevalence of small intestinal bacterial overgrowth among chronic pancreatitis patients: a case-control study. Can J Gastroenterol Hepatol 2016:7424831–7424837PubMedPubMedCentralGoogle Scholar
  85. Thorens J, Froehlich F, Schwizer W et al (1996) Bacterial overgrowth during treatment with omeprazole compared with cimetidine: a prospective, randomized double blind study. Gut 39(1):54–59CrossRefPubMedPubMedCentralGoogle Scholar
  86. Van der Pol RJ, Smits MJ, van Wijk MP et al (2011) Efficacy of proton-pump inhibitors in children with gastroesophageal reflux disease: a systematic review. Pediatr 127(5):925–935CrossRefGoogle Scholar
  87. Voigt RG, Mellon MW, Katusic SK et al (2014) Dietary docosahexaenoic acid supplementation in children with autism. J Pediatr Gastroenterol Nutr 58(6):715–722PubMedGoogle Scholar
  88. Wakefield AJ, Murch SH, Anthony A et al (1998) Ileal-lymphoid-nodular hyperplasia, non-specific colitis, and pervasive developmental disorder in children (Retracted). Lancet 351(9103):637–641CrossRefPubMedGoogle Scholar
  89. Wall R, Ross RP, Shanahan F et al (2009) Metabolic activity of the enteric microbiota influences the fatty acid composition of murine and porcine liver and adipose tissues. Am J Clin Nutr 89(5):1393–1401CrossRefPubMedGoogle Scholar
  90. Wang L, Christophersen C, Sorich M et al (2012) Elevated fecal short chain fatty acid and ammonia concentrations in children with autism spectrum disorder. Dig Dis Sci 57(8):2096–2102CrossRefPubMedGoogle Scholar
  91. Waterland RA (2006) Assessing the effects of high methionine intake on DNA methylation. J Nutr 136(6):1706S–1710SPubMedGoogle Scholar
  92. Waterland RA, Dolinoy DC, Lin JR et al (2006) Maternal methyl supplements increase offspring DNA methylation at Axin fused. Genesis 44(9):401–406CrossRefPubMedGoogle Scholar
  93. Waterland RA, Travisano M, Tahiliani KG (2007) Diet-induced hypermethylation at agouti viable yellow is not inherited transgenerationally through the female. FASEB J 21(12):3380–3385CrossRefPubMedGoogle Scholar
  94. Williams PG (2007) Nutritional composition of red meat. Nutr Dietet 64(4):S113–S119CrossRefGoogle Scholar
  95. Wood IJ, Ralston M, Ungar B et al (1964) Vitamin B12 deficiency in chronic gastritis. Gut 5:27–37CrossRefPubMedPubMedCentralGoogle Scholar
  96. Wyckoff KF, Ganji V (2007) Proportion of individuals with low serum vitamin B-12 concentrations without macrocytosis is higher in the post folic acid fortification period than in the pre folic acid fortification period. Am J Clin Nutr 86(4):1187–1192PubMedGoogle Scholar
  97. Youness ER, Aly HF, El-Bassyouni HT et al (2016) Micronucleus assay and pro-oxidant status of patients with known chromosomal aneuploidy. Der Pharma Chemica 8(13):158–164Google Scholar
  98. Zhang Y, Hodgson NW, Trivedi MS et al (2016) Decreased brain levels of vitamin B12 in aging, autism and schizophrenia. PLoS One 11(1):e0146797CrossRefPubMedPubMedCentralGoogle Scholar

Authors and Affiliations

  1. 1.GuelphCanada

Personalised recommendations