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What Is Vitamin B12?
Who Is at Risk For Low Vitamin B12?
Vitamin B12 is absorbed in the small intestine.Conditions that affect the small intestine could result in lower amounts of vitamin B12 being absorbed. This includes Crohn’s disease and celiac disease.This could also occur with people who have bariatric surgery.
Another cause of low absorption ispernicious anemia, a condition in which intrinsic factor (the protein that absorbs vitamin B12 in the stomach) is reduced, which may be due to a weakened stomach lining or an autoimmune condition.
Forpeople who can’t absorb enough vitamin B12 in the intestine, an injection of B12 might be needed.
Supplements
Supplementing with B12 isn’t necessary for most healthy people, but some people with IBD or other digestive conditions may find a need for supplements. In most cases, the deficiency is found during a blood test.A physician will then recommend a supplement, which could be an over-the-counter supplement or an injection, or a combination of the two. In some cases, supplementation daily or weekly is done until levels rise, and then supplementation is done on a less frequent basis.
Food Sources
For those who need supplements, food might not provide enough B12. However, most people are able to get their vitamin B12 needs to be met through foods. Food sources of vitamin B12 include:
Vitamin B12 from animal sources (meats, eggs, milk) is easier for the body to use. Vegetarians and vegans that don’t require supplementation can typically get enough vitamin B12 from eating a fortified breakfast cereal.
Recommended Daily Amount
The recommended daily amounts of vitamin B12, in micrograms, are:
A Word From Verywell
Vitamin B12 is important to overall health and some people with IBD, especially those who have had surgery on their small intestine, may be absorbing less than they need. Fortunately, for most people, supplementing on a regular basis will help bring the vitamin B12 level back up and start to reverse the effects of the deficiency. Supplements are available in liquid form that is easy to take every day and might be better absorbed than the B12 found in food sources. Some people might need B12 shots for a short period of time and others may need it on a more long-term basis. In some cases, shots can be given at home either doing it yourself or with the help of a friend or family member.
12 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Lyon P, Strippoli V, Fang B, Cimmino L.B vitamins and one-carbon metabolism: implications in human health and disease.Nutrients. 2020;12(9):2867. doi: 10.3390/nu12092867Serin HM, Arslan EA.Neurological symptoms of vitamin b12 deficiency: analysis of pediatric patients.Acta clinica Croatica. 2019;58.(2.):295-301. doi: 10.20471/acc.2019.58.02.13Krzywański J, Mikulski T, Pokrywka A, et al.Vitamin b12 status and optimal range for hemoglobin formation in elite athletes.Nutrients. 2020;12(4):1038. doi: 10.3390/nu12041038Temova Rakuša Ž, Roškar R, Hickey N, Geremia S.Vitamin B12 in foods, food supplements, and medicines- a review of its role and properties with a focus on its stability.Molecules. 2022;28(1):240. Published 2022 Dec 28. doi:10.3390/molecules28010240National Heart, Lung, and Blood Institute.Vitamin B12-Deficiency Anemia.Ward MG, Kariyawasam VC, Mogan SB, et al.Prevalence and risk factors for functional vitamin b12 deficiency in patients with crohnʼs disease:Inflammatory Bowel Diseases.2015;21(12):2839-2847. doi: 10.1097/MIB.0000000000000559Wang H, Li L, Qin LL, Song Y, Vidal-Alaball J, Liu TH.Oral vitamin B12 versus intramuscular vitamin B12 for vitamin B12 deficiency.Cochrane Database Syst Rev. 2018;3:CD004655. doi: 10.1002/14651858.CD004655.pub3Langan RC, Goodbred AJ.Vitamin b12 deficiency: recognition and management.Am Fam Physician. 2017;96(6):384-389. PMID: PMID: 28925645Montoro-Huguet MA, Belloc B, Domínguez-Cajal M.Small and large intestine (I): malabsorption of nutrients.Nutrients. 2021;13(4):1254. Published 2021 Apr 11. doi:10.3390/nu13041254MedlinePlus.Pernicious anemia.National Library of Medicine MedlinePlus.Vitamin B12.MacFarlane AJ, Shi Y, Greene-Finestone LS.High-dose compared with low-dose vitamin b-12 supplement use is not associated with higher vitamin b-12 status in children, adolescents, and older adults.The Journal of Nutrition. 2014;144(6):915-920. doi: 10.3945/jn.113.190256Additional ReadingOffice of Dietary Supplements. “Vitamin B12:Fact Sheet for Health Professionals.” National Institutes of Health. 11 Feb 2016.
12 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Lyon P, Strippoli V, Fang B, Cimmino L.B vitamins and one-carbon metabolism: implications in human health and disease.Nutrients. 2020;12(9):2867. doi: 10.3390/nu12092867Serin HM, Arslan EA.Neurological symptoms of vitamin b12 deficiency: analysis of pediatric patients.Acta clinica Croatica. 2019;58.(2.):295-301. doi: 10.20471/acc.2019.58.02.13Krzywański J, Mikulski T, Pokrywka A, et al.Vitamin b12 status and optimal range for hemoglobin formation in elite athletes.Nutrients. 2020;12(4):1038. doi: 10.3390/nu12041038Temova Rakuša Ž, Roškar R, Hickey N, Geremia S.Vitamin B12 in foods, food supplements, and medicines- a review of its role and properties with a focus on its stability.Molecules. 2022;28(1):240. Published 2022 Dec 28. doi:10.3390/molecules28010240National Heart, Lung, and Blood Institute.Vitamin B12-Deficiency Anemia.Ward MG, Kariyawasam VC, Mogan SB, et al.Prevalence and risk factors for functional vitamin b12 deficiency in patients with crohnʼs disease:Inflammatory Bowel Diseases.2015;21(12):2839-2847. doi: 10.1097/MIB.0000000000000559Wang H, Li L, Qin LL, Song Y, Vidal-Alaball J, Liu TH.Oral vitamin B12 versus intramuscular vitamin B12 for vitamin B12 deficiency.Cochrane Database Syst Rev. 2018;3:CD004655. doi: 10.1002/14651858.CD004655.pub3Langan RC, Goodbred AJ.Vitamin b12 deficiency: recognition and management.Am Fam Physician. 2017;96(6):384-389. PMID: PMID: 28925645Montoro-Huguet MA, Belloc B, Domínguez-Cajal M.Small and large intestine (I): malabsorption of nutrients.Nutrients. 2021;13(4):1254. Published 2021 Apr 11. doi:10.3390/nu13041254MedlinePlus.Pernicious anemia.National Library of Medicine MedlinePlus.Vitamin B12.MacFarlane AJ, Shi Y, Greene-Finestone LS.High-dose compared with low-dose vitamin b-12 supplement use is not associated with higher vitamin b-12 status in children, adolescents, and older adults.The Journal of Nutrition. 2014;144(6):915-920. doi: 10.3945/jn.113.190256Additional ReadingOffice of Dietary Supplements. “Vitamin B12:Fact Sheet for Health Professionals.” National Institutes of Health. 11 Feb 2016.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Lyon P, Strippoli V, Fang B, Cimmino L.B vitamins and one-carbon metabolism: implications in human health and disease.Nutrients. 2020;12(9):2867. doi: 10.3390/nu12092867Serin HM, Arslan EA.Neurological symptoms of vitamin b12 deficiency: analysis of pediatric patients.Acta clinica Croatica. 2019;58.(2.):295-301. doi: 10.20471/acc.2019.58.02.13Krzywański J, Mikulski T, Pokrywka A, et al.Vitamin b12 status and optimal range for hemoglobin formation in elite athletes.Nutrients. 2020;12(4):1038. doi: 10.3390/nu12041038Temova Rakuša Ž, Roškar R, Hickey N, Geremia S.Vitamin B12 in foods, food supplements, and medicines- a review of its role and properties with a focus on its stability.Molecules. 2022;28(1):240. Published 2022 Dec 28. doi:10.3390/molecules28010240National Heart, Lung, and Blood Institute.Vitamin B12-Deficiency Anemia.Ward MG, Kariyawasam VC, Mogan SB, et al.Prevalence and risk factors for functional vitamin b12 deficiency in patients with crohnʼs disease:Inflammatory Bowel Diseases.2015;21(12):2839-2847. doi: 10.1097/MIB.0000000000000559Wang H, Li L, Qin LL, Song Y, Vidal-Alaball J, Liu TH.Oral vitamin B12 versus intramuscular vitamin B12 for vitamin B12 deficiency.Cochrane Database Syst Rev. 2018;3:CD004655. doi: 10.1002/14651858.CD004655.pub3Langan RC, Goodbred AJ.Vitamin b12 deficiency: recognition and management.Am Fam Physician. 2017;96(6):384-389. PMID: PMID: 28925645Montoro-Huguet MA, Belloc B, Domínguez-Cajal M.Small and large intestine (I): malabsorption of nutrients.Nutrients. 2021;13(4):1254. Published 2021 Apr 11. doi:10.3390/nu13041254MedlinePlus.Pernicious anemia.National Library of Medicine MedlinePlus.Vitamin B12.MacFarlane AJ, Shi Y, Greene-Finestone LS.High-dose compared with low-dose vitamin b-12 supplement use is not associated with higher vitamin b-12 status in children, adolescents, and older adults.The Journal of Nutrition. 2014;144(6):915-920. doi: 10.3945/jn.113.190256
Lyon P, Strippoli V, Fang B, Cimmino L.B vitamins and one-carbon metabolism: implications in human health and disease.Nutrients. 2020;12(9):2867. doi: 10.3390/nu12092867
Serin HM, Arslan EA.Neurological symptoms of vitamin b12 deficiency: analysis of pediatric patients.Acta clinica Croatica. 2019;58.(2.):295-301. doi: 10.20471/acc.2019.58.02.13
Krzywański J, Mikulski T, Pokrywka A, et al.Vitamin b12 status and optimal range for hemoglobin formation in elite athletes.Nutrients. 2020;12(4):1038. doi: 10.3390/nu12041038
Temova Rakuša Ž, Roškar R, Hickey N, Geremia S.Vitamin B12 in foods, food supplements, and medicines- a review of its role and properties with a focus on its stability.Molecules. 2022;28(1):240. Published 2022 Dec 28. doi:10.3390/molecules28010240
National Heart, Lung, and Blood Institute.Vitamin B12-Deficiency Anemia.
Ward MG, Kariyawasam VC, Mogan SB, et al.Prevalence and risk factors for functional vitamin b12 deficiency in patients with crohnʼs disease:Inflammatory Bowel Diseases.2015;21(12):2839-2847. doi: 10.1097/MIB.0000000000000559
Wang H, Li L, Qin LL, Song Y, Vidal-Alaball J, Liu TH.Oral vitamin B12 versus intramuscular vitamin B12 for vitamin B12 deficiency.Cochrane Database Syst Rev. 2018;3:CD004655. doi: 10.1002/14651858.CD004655.pub3
Langan RC, Goodbred AJ.Vitamin b12 deficiency: recognition and management.Am Fam Physician. 2017;96(6):384-389. PMID: PMID: 28925645
Montoro-Huguet MA, Belloc B, Domínguez-Cajal M.Small and large intestine (I): malabsorption of nutrients.Nutrients. 2021;13(4):1254. Published 2021 Apr 11. doi:10.3390/nu13041254
MedlinePlus.Pernicious anemia.
National Library of Medicine MedlinePlus.Vitamin B12.
MacFarlane AJ, Shi Y, Greene-Finestone LS.High-dose compared with low-dose vitamin b-12 supplement use is not associated with higher vitamin b-12 status in children, adolescents, and older adults.The Journal of Nutrition. 2014;144(6):915-920. doi: 10.3945/jn.113.190256
Office of Dietary Supplements. “Vitamin B12:Fact Sheet for Health Professionals.” National Institutes of Health. 11 Feb 2016.
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