What is the function of Vitamin B12 (Cobalamin)?

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Last updated: April 23, 2025View editorial policy

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From the Guidelines

Vitamin B12 plays a crucial role in various bodily processes, including the formation of red blood cells, neurological function, DNA synthesis, and energy metabolism, and its deficiency can lead to severe health issues, including anemia, fatigue, and neurological problems, emphasizing the need for prompt treatment and maintenance therapy. The most recent and highest quality study, 1, highlights the importance of vitamin B12 in preventing stroke, with evidence suggesting that B vitamins, including B12, can reduce the risk of ischemic stroke by 43%. This study recommends supplementation with B vitamins, specifically methylcobalamin or hydroxocobalamin, to reduce stroke risk.

Key Functions of Vitamin B12

  • Formation of red blood cells
  • Support of neurological function
  • Aid in DNA synthesis
  • Contribution to energy metabolism
  • Production of myelin, the protective covering around nerves
  • Involvement in immune function and mood regulation through the production of S-adenosylmethionine (SAMe)

Treatment and Maintenance of Vitamin B12 Deficiency

  • Hydroxocobalamin 1 mg intramuscularly should be administered on alternate days until there is no further improvement, then hydroxocobalamin 1 mg intramuscularly every 2 months for patients with neurological involvement 1
  • For people with no neurological involvement, hydroxocobalamin 1 mg intramuscularly should be administered three times a week for 2 weeks, followed by maintenance treatment with 1 mg intramuscularly every 2–3 months for life 1
  • Urgent specialist advice from a neurologist and haematologist should be sought if there is possible neurological involvement, such as unexplained sensory and/or motor and gait symptoms 1

Importance of Vitamin B12 in Preventing Stroke

  • B vitamins, including B12, can reduce the risk of ischemic stroke by 43% 1
  • Supplementation with B vitamins, specifically methylcobalamin or hydroxocobalamin, is recommended to reduce stroke risk 1
  • All patients with ischemic stroke should have their serum B12 and tHcy measured and treated if abnormal 1

From the FDA Drug Label

Vitamin B12 is essential to growth, cell reproduction, hematopoiesis, and nucleoprotein and myelin synthesis. The main functions of vitamin B12 are:

  • Growth
  • Cell reproduction
  • Hematopoiesis (production of blood cells)
  • Nucleoprotein synthesis
  • Myelin synthesis (production of the fatty substance that surrounds and protects nerve fibers) 2

From the Research

Vitamin B12 Function

  • Vitamin B12, also known as cobalamin, plays a crucial role in various bodily functions, including the production of red blood cells and the maintenance of the nervous system 3.
  • It is essential for the synthesis of DNA, fatty acids, and energy production 4.
  • Vitamin B12 deficiency can lead to pernicious anemia, a condition characterized by a lack of red blood cells, which can cause fatigue, weakness, and shortness of breath 5, 3.

Role in Pernicious Anemia

  • Pernicious anemia is an autoimmune disease that causes the body to produce antibodies against intrinsic factor, a protein necessary for vitamin B12 absorption 3.
  • Vitamin B12 supplementation is essential for treating pernicious anemia, and oral supplementation with 1000 μg/d of cyanocobalamin has been shown to improve vitamin B12 deficiency in patients with pernicious anemia 5.
  • The absorption of vitamin B12 is hindered in pernicious anemia due to intrinsic factor deficiency, but oral vitamin B12 supplementation can bypass this impairment through passive enteral absorption 5.

Biochemical Role and Properties

  • Vitamin B12 has four forms: cyanocobalamin, hydroxocobalamin, 5'-deoxyadenosylcobalamin, and methylcobalamin, each with different biochemical roles and properties 4.
  • The stability of vitamin B12 depends on various environmental factors, such as temperature, pH, and light, as well as the presence of interacting compounds 4.
  • The manufacturing process and storage conditions can affect the stability of vitamin B12 in foods, food supplements, and medicines, highlighting the need for proper stabilization techniques 4.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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