The EclecticPhysician

The Eclectic Physician
Vitamin and Mineral Information

Vitamin B-12/Cobalamin

The information on this page compiled by
Beth Burch N.D.
(click on the keywords)


Vitamin B-12 or cobalamin is important in the manufacture of neurotransmitters, in the replication of DNA, in the production of energy in the cell and in the metabolism of homocysteine. It is vital for proper brain and nerve function and production of red blood cells. Without adequate vitamin B-12, folic acid deficiency occurs. Vitamin B-12 deficiency results in nervous system impairment and damage with symptoms of numbness and tingling in the extremities, leg weakness and stiffness, difficulty walking, fatigue, confusion, depression, irritability, paranoia and yellow-blue color blindness. Deficiency also causes a megaloblastic anemia and may be accompanied by spleen and liver enlargement, anorexia, constipation, diarrhea and abdominal pain. Other symptoms of deficiency include a swollen red tongue and rarely fever. Deficiency can be caused by a prolonged vegan diet without supplementation, alcoholism, decreased production of intrinsic factor, malabsorption states and liver or kidney disease. Requirem ents for vitamin B-12 are increased in hyperthyroidism and parasite infections, as well as vitamin B-12 dependency states. Deficiency is common in the elderly (3). New research suggests that vitamin B-12 deficiency may increase the risk for breast cancer (2). Vitamin B-12 deficiency is associated with an increased risk of neural tube defects (4).

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  • Cyanocobalamin
  • Hydroxycobalamin
  • Methylcobalamin (activated cobalamin)

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Food Sources

  • High levels of vitamin B-12 are found in all animal foods including meat, eggs, cheese and fish. Vegans will want to supplement their diet with vitamin B-12 to avoid deficiency (5)

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  • Recommended Daily Allowance (RDA)
  • Infants- 0.3-0.5 mcg
  • Children (ages 1-10)- 0.7-1.4 mcg
  • Adults- 2.0 mcg
  • Pregnancy- 2.2 mcg
  • Lactation- 2.6 mcg

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Optimal Supplementation

  • 100 mcg daily

Treatment of Health Conditions

  • 1000-2000 mcg daily orally or by injection

Conditions used for

  • Dementia in the elderly including Alzheimerís disease (1,6,8)
  • Asthma (9)
  • Depression (8)
  • Male infertility (10)
  • Multiple sclerosis (11)
  • Tinnitus (12)
  • Elevated homocysteine levels (with vitamin B-6 and folic acid) (13)
  • Vitamin B-12 deficiency

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Side effects

  • Use cautiously with cardiovascular disease, lung disease and hypertension and in severe vitamin B-12 deficiency
  • Diarrhea, blood clots, pulmonary edema, congestive heart failure

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  • Hypersensitivity to cobalamin products or cobalt
  • Early Leberís disease

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Interactions with other nutrients

  • Works with folic acid

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Interactions with medications and herbs

  • Metformin, histamine H-2 receptor antagonists (cimetidine, ranitidine, etc), aminoglycosides, colchicine, aminosalicylic acid, anticonvulsants and alcohol decrease absorption of vitamin B-12 (7,13)
  • Donít use with chloramphenicol
  • Donít take vitamin C within an hour of taking vitamin B-12 because vitamin C inactivates B-12

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1. Cunha UG et al, Vitamin B12 deficiency and dementia, Int Psychogeriatr 1995;7(1):85-8
2. Choi SW, Vitamin B12 deficiency: a new risk factor for breast cancer?, Nutr Rev 1999;57(8):250-3
3. Baik HW, Vitamin B12 deficiency in the elderly, Annu Rev Nutr 1999;19:357-77
4. Wilson A et al, A common variant in methionine synthase reductase combined with low cobalamin (vitamin B12) increases risk for spina bifida, Mol Genet Metab 1999;67(4):317-23
5. Pongstaporn W et al, Hematological parameters, ferritin and vitamin B12 in vegetarians, J Med Assoc Thai 1999;82(3):304-11
6. Wynn M et al, The danger of B12 deficiency in the elderly, Nutr Health 1998;12(4):215-26
7. Lee AJ, Metformin in noninsulin-dependent diabetes mellitus, Pharmacotherapy 1996;16(3):327-51
8. Bottiglieri T, Folate, vitamin B12, and neuropsychiatric disorders, Nutr Rev 1996;54(12):382-90
9. Anibarro B et al, Asthma with sulfite intolerance in children: a blocking study with cyanocobalamin, J Allergy Clin Immunol 1992;90(1):103-9
10. Moriyama H et al, Studies on the usefulness of a long-term, high-dose treatment of methylcobalamin in patients with oligozoospermia,Hinyokika Kiyo 1987 Jan;33(1):151-6
11. Kira J et al, Vitamin B12 metabolism and massive-dose methyl vitamin B12 therapy in Japanese patients with multiple sclerosis, Intern Med 1994;33(2):82-6
12. Shemesh Z et al, Vitamin B12 deficiency in patients with chronic-tinnitus and noise-induced hearing loss, Am J Otolaryngol 1993;14(2):94-9
13. Aymard JP et al, Haematological adverse effects of histamine H2-receptor antagonists, Med Toxicol Adverse Drug Exp 1988;3(6):430-48
14. Selhub J et al, Homocysteine metabolism, Annu Rev Nutr 1999;19:217-46

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* The information presented in this web site is intended to inform and educate. It is not intended replace a qualified medical practitioner to diagnose or treat medical conditions.

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