What is vitamin B12?

Vitamin B12 , also known as cobalamin , is a water-soluble B-complex vitamin that plays an exceptionally important role in energy metabolism, blood formation, nerve function, and DNA synthesis . It is the only vitamin that contains a metal ion (cobalt) – hence the name – and is produced exclusively by microorganisms (bacteria).

Since vitamin B12 is only found in significant amounts in animal products (e.g., meat, fish, eggs, dairy products), vegetarians and vegans are particularly at risk of developing a deficiency. Adequate intake is crucial for the health of the brain, nerves, and blood cells.

Vitamin B12 is stored in the liver – sometimes for several years – and thus serves as a reserve. However, its absorption in the intestine requires a special transport protein, the so-called intrinsic factor , which is produced in the stomach lining.

How does vitamin B12 work?

Vitamin B12 is involved in numerous vital processes and acts as a coenzyme in several central metabolic pathways.

Energy and cell metabolism:
Cobalamin is essential for converting nutrients into energy. It supports the breakdown of fatty acids and amino acids and contributes to the formation of ATP – the most important energy source for cells. A deficiency can lead to fatigue, lack of energy, and muscle weakness.

Blood formation:
Vitamin B12 is necessary for the formation and maturation of red blood cells in the bone marrow. Together with folic acid, it ensures healthy cell division. A deficiency leads to megaloblastic anemia , which manifests as paleness, shortness of breath, dizziness, and weakness.

Nervous system and brain function:
Vitamin B12 is essential for the formation of the myelin sheath – the protective covering that surrounds nerve fibers and enables rapid signal transmission. A deficiency can lead to tingling, numbness, difficulty concentrating, mood swings, or even permanent nerve damage. It also plays a role in the synthesis of neurotransmitters that influence mood and mental clarity.

Homocysteine ​​levels and heart health:
Together with vitamin B6 and folic acid, vitamin B12 helps break down homocysteine , an amino acid that, at elevated concentrations, can promote inflammation and vascular damage. This actively contributes to the protection of the cardiovascular system .

DNA synthesis and cell regeneration:
Cobalamin is crucial for DNA replication and repair. Particularly rapidly dividing cells – such as those in bone marrow, mucous membranes, and skin – depend on an adequate supply.

Benefits of Vitamin B12

  • Supports energy production and reduces fatigue

  • Promotes the formation of red blood cells and prevents anemia.

  • Protects the nervous system and improves concentration and memory.

  • Supports DNA synthesis and cell regeneration

  • Regulates homocysteine ​​levels and strengthens the heart and blood vessels.

  • It improves mood and can alleviate depressive symptoms.

  • Supports immune system and brain function

  • Important for a healthy pregnancy and child development

Possible side effects and interactions

Vitamin B12 is very well tolerated, as excess amounts are excreted in the urine. Even high doses in the form of dietary supplements are considered safe, since the body only absorbs as much as it needs.

A deficiency is common in older people, vegans, vegetarians, and individuals with malabsorption (e.g., gastritis, celiac disease, chronic bowel disease, or after stomach surgery). Symptoms often develop gradually and can be neurological or hematological.

Certain medications such as metformin (for diabetes), proton pump inhibitors (e.g., omeprazole) or birth control pills can impair the absorption of vitamin B12.

Conclusion

Vitamin B12 is a vital all-rounder for energy, nerves, blood, and brain function. It supports body and mind in numerous ways – from cell regeneration and nerve conduction to protecting the cardiovascular system. Since it is found almost exclusively in animal products, vegans, the elderly, and people with digestive problems should pay particular attention to their intake. High-quality supplements containing methylcobalamin or hydroxocobalamin offer particularly good bioavailability and effectively contribute to maintaining performance, mental clarity, and overall well-being.

Sources

  1. O'Leary F, Samman S. (2010): Vitamin B12 in health and disease. Nutrients , 2(3), 299–316.

  2. Allen LH. (2009): Causes of vitamin B12 and folate deficiency. Food Nutr Bull , 29(2 Suppl), S20–S34.

  3. Green R, et al. (2017): Vitamin B12 deficiency. Nat Rev Dis Primers , 3, 17040.

  4. Hunt A, Harrington D, Robinson S. (2014): Vitamin B12 deficiency. BMJ , 349, g5226.