Vitamin B12
Supports red blood cell production and nervous system health.
Vitamin B12 is a water-soluble vitamin in the cobalamin family whose molecules contain a central cobalt atom. It occurs naturally in animal-derived foods and is produced by bacterial fermentation; supplementation is commonly recommended for people following vegetarian or vegan diets. As a biochemical cofactor, vitamin B12 is involved in red blood cell synthesis, DNA formation and cell division, and in maintaining the integrity of the nervous system.
Supplemental forms include methylcobalamin, adenosylcobalamin, hydroxocobalamin and cyanocobalamin, and are available as tablets, capsules, powders, liquids and injectable preparations. Recommended intakes vary by age and life stage (for example, about 0.5 µg for infants to around 2.3 µg for adults, with slightly higher targets suggested for older adults), but individual needs and responses differ; deficiency may be associated with megaloblastic anemia and neurological or cognitive symptoms in some people. Toxicity is not generally reported, though regulatory bodies advise an upper intake threshold, so supplementation should consider personal factors and professional guidance.
At a Glance
Cobalamins, commonly called vitamin B12, are cobalt-containing water-soluble compounds produced by bacteria and concentrated in animal-derived foods and some algae. They participate in red blood cell production, DNA synthesis, cell division and maintenance of nervous system tissues.
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| Classification | Water-soluble vitamin |
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Origin & History
Vitamin B12 originates from microbial biosynthesis and is concentrated in animal tissues; bacteria produce cobalamin compounds that accumulate in meat, fish and shellfish. Natural sources include organ meats, certain seafood and microbial cultures or algal preparations, while the human body cannot synthesize this vitamin on its own.
Clinical descriptions of a severe, pernicious form of anemia were later linked to deficiency of this nutrient, and researchers subsequently isolated cobalamin compounds from bacterial fermentations used in antibiotic production. These developments shaped recognition of the vitamin’s essential role and supported the production of several supplemental forms derived from microbial fermentation for populations with low dietary intake.
Composition & Active Compounds
Vitamin B12 compounds are cobalt-containing corrin-ring molecules that commonly appear as red to dark-red crystalline substances and are available in several chemically distinct cobalamin forms. These molecules share a central cobalt atom bound to different ligands; the ligand determines each form’s stability, route of use in supplements and its role in biochemical pathways.
Methylcobalamin and adenosylcobalamin are the biologically active cobalamin forms most relevant to human metabolic processes.
- Methylcobalamin: active coenzyme form involved in methyl-group transfers and maintenance of nervous system tissues.
- Adenosylcobalamin: mitochondrial coenzyme important for cellular energy metabolism.
- Hydroxocobalamin: naturally produced intermediate form often used in injectable preparations and in conversion to active coenzymes.
- Cyanocobalamin: stable synthetic form commonly used in oral supplements.
Related Herbs
Properties & Effects
Vitamin B12 is a water-soluble cobalamin traditionally recognized for supporting blood formation, nervous system integrity and normal cellular metabolism. It is obtained from microbially produced cobalamins concentrated in animal foods and used in supplements to address low dietary intake.
Vitamin B12 is most noted for its role in supporting normal red blood cell formation.
- Immunity: may support normal functioning of the immune system.
- Red blood cell formation: may support the normal production and maturation of red blood cells.
- Tissue formation and renewal: may support DNA synthesis and healthy cell division involved in tissue maintenance.
- Nervous system function: may support maintenance of nerve tissues and nervous system health.
- Energy production: may support cellular energy metabolism and normal energy release processes.
Dosage & How to Use
Recommended intakes of vitamin B12 vary by age and life stage.
| Infants | 0.5 µg |
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| Adolescents and adults | 2.3 µg |
| Older adults | 3 µg |
| Safety limit | 1 mg per day |
Safety, Side Effects & Contraindications
The provided facts report no general toxicity or adverse effects associated with vitamin B12. Regulatory guidance included in the facts advises a recommended upper intake threshold to guide safe supplementation.
No specific contraindications are listed in the facts; known side effects and drug interactions are not reported there. Individuals with existing medical conditions or those taking multiple medications should consider professional advice before beginning or changing supplementation, as personal circumstances can affect suitability.
- Safety limit: EFSA advises a safe upper intake threshold of 1 mg per day.
Consult a healthcare professional before use; follow recommended dosages and regulatory guidance and do not exceed advised safety limits (EFSA recommends up to 1 mg/day).