Individuals following vegetarian diets are at risk for developing vitamin B12 deficiency owing to suboptimal intake. As vitamin B12 is essential for the synthesis of nucleic acids, erythrocytes and in the maintenance of myelin, deficiency may result in a variety of symptoms. Some of these symptoms may be severe while others may be irreversible. The objective of this review was to assess vitamin B12 deficiency, based on reported serum vitamin B12, among individuals adhering to different types of vegetarian diets. A systematic literature search was carried out using multiple search engines including PubMed, Medline, CINAHL plus, ERIC, Nursing and Allied Health Collection and Nursing/Academic Edition. The inclusion criteria consisted of original studies that assessed serum vitamin B12, studies written in English, non-case studies and studies that reported actual percentages of vitamin B12 deficiency. Forty research studies were included. The deficiency prevalence among infants reached 45%. The deficiency among the children and adolescents ranged from 0 to 33.3%. Deficiency among pregnant women ranged from 17 to 39%, dependent on the trimester. Adults and elderly individuals had a deficiency range of 0–86.5%. Higher deficiency prevalence was reported in vegans than in other vegetarians. Thus, with few exceptions, the reviewed studies documented relatively high deficiency prevalence among vegetarians. Vegans who do not ingest vitamin B12 supplements were found to be at especially high risk. Vegetarians, especially vegans, should give strong consideration to the use of vitamin B12 supplements to ensure adequate vitamin B12 intake. Vegetarians, regardless of the type of vegetarian diet they adhere to, should be screened for vitamin B12 deficiency.
This is a preview of subscription content
Subscribe to Journal
Get full journal access for 1 year
only $9.92 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Tax calculation will be finalised during checkout.
Get time limited or full article access on ReadCube.
All prices are NET prices.
National Institute of Health NIH Office of Dietary Supplements. Dietary Supplement Fact Sheet: Vitamin B12. Available at: http://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/. Accessed on 15 November 2013.
Institute of Medicine. Food and Nutrition Board Dietary Reference Intakes: Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. Washington, DC, USA: National Academy Press, 1998.
Craig WJ . Nutrition concerns and health effects of vegetarian diets. Nutr Clin Pract 2010; 25: 613–620.
Elmadfa I, Singer I . Vitamin B-12 and homocysteine statues among vegetarians: a global perspective. Am J Clin Nutr 2009; 89: 1693s–1698s.
Herrmann W, Obeid R . Causes and early diagnosis of vitamin B12 deficiency. Dtsch Arztebl Int 2008; 105: 680–685.
Escott-Stump S . Nutrition and Diagnosis-Related Care. Baltimore, MD, USA: Lippincott Williams & Wilkins, 2008.
Pawlak R, James PS, Raj S, Cullum-Dugan D, Lucus D . How prevalent is vitamin B12 deficiency among vegetarians? Nutr Rev 2013; 71: 110–117.
Gammon CS, vonHurst PR, Coad J, Kruger R, Stonehouse W . Vegetarianism, vitamin B12 status, and insulin resistance in a group of predominately overweight/obese South Asian women. Nutr 2012; 28: 20–24.
Gilsing AMJ, Crowe FL, Lloyd-Wright Z, Sanders TA, Appleby PN, Allen NE et al. Serum concentrations of vitamin B12 and folate in British male omnivores, vegetarians, and vegans: results from a cross-sectional analysis of the EPIC-Oxford cohort study. Eur J Clin Nutr 2010; 64: 933–939.
Donaldson MS . Metabolic vitamin B12 status on a mostly raw vegan diet with follow-up using tablets, nutritional yeast, or probiotic supplements. Ann Nutr Metab 2000; 44: 229–234.
Lowik MRH, Schrijver J, Odink J, van den Berg H, Wedel M . Long-term effects of a vegetarian diet on the nutritional status of elderly people (Dutch Nutrition Surveillance System). J Am Coll Nutr 1990; 9: 600–609.
Bar-Sella P, Rakover Y, Ratner D . Vitamin B12 and folate levels in long-term vegans. Isr J Med Sci 1990; 26: 309–312.
Pongstaporn W, Bunyaratavej A . Hematological parameters, ferritin and vitamin B12 in vegetarians. J Med Assoc Thai 1999; 82: 304–310.
Leung SSF, Lee RHY, Sung RYT, Luo HY, Kam CW, Yuen MP et al. Growth and nutrition of Chinese vegetarian children in Hong Kong. J Paediatr 2001; 37: 247–253.
Gupta AK, Damji A, Uppaluri A . Vitamin B12 deficiency—prevalence among South Asians at a Toronto clinic. Can Fam Physician 2004; 50: 743–747.
Barghouti FF, Younes NA, Halaseh LJ, Said TT, Ghraiz SM . High frequency of low serum levels of vitamin B12 among patients attending Jordan University Hospital. East Mediterr Health J 2009; 15: 853–860.
Krajcovicova-Kudlackova M, Blazicek P, Mislanova C et al. Nutritional determinants of plasma homocysteine. Bratisl Lek Listy 2007; 108: 510–515.
Yajnik CS, Deshpande SS, Lubree HG, Naik SS, Bhat DS, Uradey BS et al. Vitamin B12 deficiency and hyperhomocysteinemia in rural and urban Indians. J Assoc Physicians India 2006; 54: 775–782.
Morad M, Gringols M, Kandel I, Valachovicova M, Paukova V, Spustova V . Vitamin B12 deficiency in persons with intellectual disability in a vegetarian residential care community. Scientific World J. 2005; 5: 58–61.
Madry E, Lisowska A, Grebowiec P, Walkowiak J . The impact of vegan diet on B-12 status in healthy omnivores: five-year prospective study. Acta Sci Pol Technol Aliment 2012; 11: 209–213.
Lee Y, Krawinkel M . The nutritional status of iron, folate, and vitamin B-12 of Buddhist vegetarians. Asia Pac J Clin Nutr 2011; 20: 42–49.
Yen CE, Yen CH, Cheng CH, Huang YC . Vitamin B-12 status is not associated with plasma homocysteine in parents and their preschool children: lacto-ovo, lacto, and ovo vegetarians and omnivores. J Am Coll Nutr 2010; 29: 7–13.
Majchrzak D, Singer I, Manner M, Rust P, Genser D, Wagner KH et al. B-vitamin status and concentrations of homocysteine in Austrian omnivores, vegetarians and vegans. Ann Nutr Metab 2006; 50: 485–491.
Karabudak E, Kiziltan G, Cigerim N . A comparison of some of the cardiovascular risk factor in vegetarian and omnivorous Turkish females. J Hum Nutr Diet 2008; 21: 13–22.
Rush EC, Chhichha P, Hinckon E, Nabiryo C . Dietary patterns and vitamin B12 status of migrant Indian preadolescent girls. Eur J Clin Nutr 2009; 63: 585–587.
Waldmann A, Koschizke JW, Leitzmann C, Hahn A . German vegan study: diet, life-style factors, and cardiovascular risk profile. Ann Nutr Metab 2005; 49: 366–372.
Koebnick C, Hoffmann I, Dagnelie PC, Heins UA, Wickramasinghe SN, Ratnayaka ID et al. Long-term ovo-lacto vegetarian diet impairs vitamin B-12 status in pregnant women. J Nutr 2004; 134: 3319–3326.
Waldmann A, Koschizke JW, Leitzman C, Hahn A . Homocysteine and cobalamin status in German vegans. Public Health Nutr 2004; 7: 467–472.
Herrmann W, Schorr H, Obeid R, Geisel J . Vitamin B-12 status, particularly holotranscobalamin II and methylmalonic acid concentrations, and hyperhomocysteinemia in vegetarians. Am J Clin Nutr 2003; 78: 131–136.
Carmel R, Mallidi PV, Vinarskiy S, Brar S, Frouhar Z . Hyperhomocysteinemia and cobalamin deficiency in young Asian Indians in the United States. Am J Hematol 2002; 70: 107–114.
Larsson C, Johansson G . Dietary intake and nutritional status of young vegans and omnivores in Sweden. Am J Clin Nutr 2002; 76: 100–106.
Bissoli L, Di Francesco V, Ballarin A, Mandragona R, Trespidi R, Brocco G et al. Effect of vegetarian diet on homocysteine levels. Ann Nutr Metab 2002; 46: 73–79.
Hung CJ, Huang PC, Lu SC, Li YH, Huang HB, Lin BF et al. Plasma homocysteine levels in Taiwanese vegetarians are higher than those of omnivores. J Nutr 2002; 132: 152–158.
Refsum H, Yajnik CS, Gadkari M, Schneede J, Vollset SE, Orning L et al. Hyperhomocysteinemia and elevated methylmalonic acid indicate a high prevalence of cobalamin deficiency in Asian Indians. Am J Clin Nutr 2001; 74: 233–241.
Herrmann W, Schorr H, Purschwitz K, Rassoui F, Richter V . Total homocysteine, vitamin B12, and total antioxidant status in vegetarians. Clinical Chemistry. 2001; 47, 1094–1101.
Krajcovicova-Kudlackova M, Blazicek P, Kopcova J, Bederova A, Babinska K . Homocysteine levels in vegetarians versus omnivores. Ann Nutr Metab 2000; 44: 135–138.
Haddad EH, Berk LS, Kettering JD, Hubbard RW, Peters WR . Dietary intake and biochemical, hematologic, and immune status of vegans compared with nonvegetarians. Am J Clin Nutr 1999; 70: 586S–593S.
Hokin BD, Butler T . Cyanocobalamin (vitamin B-12) status in Seventh-day Adventist ministers in Australia. Am J Clin Nutr 1999; 70: 576S–578S.
Alexander D, Ball MJ, Mann J . Nutrient intake and haematological status of vegetarians and age-sex matched omnivores. Eu J Clin Nutr 1994; 48: 538–546.
Woo J, Kwok T, Ho SC, Sham A, Lau E . Nutritional status of elderly Chinese vegetarians. Age and Aging 1998; 27: 455–461.
Krivosikova Z, Krajcovicova-Kudlackova M, Spustova V et al. The association between high plasma homocysteine levels and lower bone mineral density in Slovak women: the impact of vegetarian diet. Eur J Nutr 2010; 49: 147–153.
Ingenbleek Y, McCully KS . Vegetarian produces subclinical malnutrition, hyperhomocysteinemia, and atherogenesis. Nutr 2012; 28: 148–153.
Rauma AL, Torronen R, Hanninen O, Mykkanen H . Vitamin B-12 status of long-term adherents of a strict uncooked vegan diet (‘living food diet’) is compromised. J Nutr 1995; 125: 2511–2515.
Miller DR, Specker BL, Ho ML, Norman EJ . Vitamin B-12 status in a macrobiotic community. Am J Clin Nutr 1991; 53: 524–529.
Specker BL, Miller D, Norman EJ, Greene H, Hayes KC . Increased urinary methylmalonic acid excretion in breast-fed infants of vegetarian mother and identification of an acceptable dietary source of vitamin B-12. Am J Clin Nutr 1988; 47: 89–92.
Crane M, Sample C . Vitamin B12 studies in total vegetarians (vegans). J Nutr Med 1994; 4: 419–430.
Dagnelie PC, van Staveren WA, Vergote FJVRA, Dingjan PG, van den Berg H, Hautvast JGAJ . Increased risk of vitamin B-12 and iron deficiency in infants on macrobiotic diets. Am J Clin Nutr 1989; 50: 818–824.
Rowlett R University of North Carolina at Chapel Hill SI units for clinical data. How many? A dictionary of units of measurement. Available at: http://www.unc.edu/~rowlett/units/scales/clinical_data.html (last accessed 13 June 2001).
Grace ND . Effect of ingestion of soil on the iodine, copper, cobalt (vitamin B12) and selenium status of grazing sheep. NZ Vet J 2006; 54: 44–47.
Hytten F . Blood volume changes in normal pregnancy. Clin Haematol 1985; 14: 601–612.
Dror DK, Allen LH . Effect of vitamin B12 deficiency on neurodevelopment in infants: current knowledge and possible mechanisms. Nutr Rev 2008; 66: 250–255.
Pawlak R, Parrott SJ, Raj. S, Cullum-Dugan D, Lucus D . Understanding vitamin B12. Am J Lifestyle Med 2012; 7: 59–65.
The Academy of Nutrition and Dietetics (formerly the American Dietetic Association). Position of the American Dietetic Association: vegetarian diets. J Am Diet Assoc 2009; 109: 1266–1282.
Herbert V . Staging vitamin B-12 (cobalamin) status in vegetarians. Am J Clin Nutr 1994; 59: 1213S–1222S.
The authors did not receive any financial compensation for creating this manuscript.
The authors declare no conflict of interest.
About this article
Cite this article
Pawlak, R., Lester, S. & Babatunde, T. The prevalence of cobalamin deficiency among vegetarians assessed by serum vitamin B12: a review of literature. Eur J Clin Nutr 68, 541–548 (2014). https://doi.org/10.1038/ejcn.2014.46
Diets for weight management in adults with type 2 diabetes: an umbrella review of published meta-analyses and systematic review of trials of diets for diabetes remission
Intake of micronutrients and fatty acids of vegetarian, vegan, and omnivorous children (1–3 years) in Germany (VeChi Diet Study)
European Journal of Nutrition (2022)
Improvement in vitamin B12 status of Wistar rats by supplementing the diet with Chlorella vulgaris biomass
Journal of Food Science and Technology (2021)
Chlorella vulgaris cultivation in airlift photobioreactor with transparent draft tube: effect of hydrodynamics, light and carbon dioxide on biochemical profile particularly ω-6/ω-3 fatty acid ratio
Journal of Food Science and Technology (2020)
Metformin Usage Index and assessment of vitamin B12 deficiency among metformin and non-metformin users with type 2 diabetes mellitus
Acta Diabetologica (2020)