Vitamin B12
Vitamin B12 (cobalamin) is a water-soluble B vitamin essential for nerve function, red blood cell formation, and DNA synthesis. Deficiency is common among vegans and the elderly.
What is vitamin B12?
Vitamin B12 (cobalamin) is the most complex of all vitamins. It plays a crucial role in nerve function, blood formation, and cell division. B12 is found almost exclusively in animal foods.
Functions
- Nervous system — B12 is required to form and maintain the myelin sheath that protects nerve fibres.
- Blood formation — Without B12, the body cannot produce normal red blood cells, leading to megaloblastic anaemia.
- Energy — B12 is involved in energy metabolism. Deficiency can cause chronic fatigue.
- DNA synthesis — Required for normal cell division, especially important during pregnancy.
Forms
- Cyanocobalamin — Synthetic form, stable and inexpensive. Must be converted in the body.
- Methylcobalamin — Active form, directly utilizable. Best choice for most people.
- Adenosylcobalamin — Active form used in mitochondria.
- Hydroxocobalamin — Often used in injections. Long half-life.
Risk groups for deficiency
Vegans, vegetarians, elderly (reduced intrinsic factor production), people with Crohn's disease or coeliac disease, and those taking proton pump inhibitors.
Dosage
RDI: 2.4 µg. Sublingual tablets: 1000–5000 µg. Vegans should take B12 supplements daily.
Swedish recommendations (National Food Agency)
The National Food Agency's recommendations for daily intake of vitamin B12:
| Age group | Recommended intake |
|---|---|
| Children 2–5 years | 0.8 µg |
| Children 6–9 years | 1.3 µg |
| Adolescents 10–17 years | 2.0 µg |
| Adults 18+ years | 2.0 µg |
| Pregnant women | 2.0 µg |
| Lactating women | 2.6 µg |
| Vegans (all ages) | Supplementation is strongly recommended |
Source: National Food Agency, NNR 2023. Vegans must take B12 supplements as the vitamin is found almost exclusively in animal foods.