Vitamin B12
kobalamina · last AI check: 2026-07-19
In short
Found mainly in animal products. Plant-based diets require conscious supplementation.
What it does in the body
The sentences below are officially authorised EU health claims.
Vitamin B12 contributes to normal energy-yielding metabolism EU health claim
Commission Regulation (EU) No 432/2012 of 16 May 2012, Annex — list of permitted health claims · register entry: 99, 190 · EFSA opinion: 2009;7(9):1223
Condition of use on a product: The product is at least a source of Vitamin B12.
Vitamin B12 contributes to the reduction of tiredness and fatigue EU health claim
Commission Regulation (EU) No 432/2012 of 16 May 2012, Annex — list of permitted health claims · register entry: 108 · EFSA opinion: 2010;8(10):4114
Condition of use on a product: The product is at least a source of Vitamin B12.
How much you need
| Country / organisation | Group | Value | Type |
|---|---|---|---|
| EFSA | adults | AI Adequate intake — an approximate value used when data are insufficient to set an exact requirement (RDA). | |
| FAO | adult men | RNI Reference nutrient intake — the RDA equivalent in WHO/FAO, UK and Philippine terminology. | |
| NASEM (US/CA) | adults | RDA Recommended daily allowance — covers the needs of almost all healthy people in a group. | |
| Philippines | adults | RNI Reference nutrient intake — the RDA equivalent in WHO/FAO, UK and Philippine terminology. | |
| India | adults | RDA Recommended daily allowance — covers the needs of almost all healthy people in a group. | |
| Poland | adults | RDA Recommended daily allowance — covers the needs of almost all healthy people in a group. | |
| Singapore | adults | RDA Recommended daily allowance — covers the needs of almost all healthy people in a group. | |
| Switzerland | adults | RDA Recommended daily allowance — covers the needs of almost all healthy people in a group. | |
| United Kingdom | adults | RNI Reference nutrient intake — the RDA equivalent in WHO/FAO, UK and Philippine terminology. |
Reference values from different countries are not directly comparable — they differ in definition and age group. How to read reference values →
Every value states its source — click it to see the document, location and link.Data and content are prepared and cross-checked against source documents by several independent AI models. They have not been audited by a human editor.Before citing a value, check it in the source document — verification is automated (AI), not editorial.
Worth knowing
Vitamin B12 is unique in one respect: no plant or animal organism produces it. It is made exclusively by micro-organisms, and it gets into meat, fish, eggs and dairy thanks to bacteria living in animals' digestive tracts or via feed. This is why it is practically absent from plant foods — and supplements and fortified foods are based on B12 from bacterial cultures, not from animal-derived raw materials.
Why deficiency shows up late
The body stores vitamin B12 in the liver, and the reserves last a long time — symptoms of deficiency may only appear after years of insufficient intake. This is deceptive, because the absence of symptoms in the early period of a diet excluding animal products doesn't mean intake is sufficient.
Absorption can be a problem independent of diet
B12 requires a protein called intrinsic factor, produced in the stomach, in order to be absorbed. With stomach and intestinal diseases, after certain surgical procedures, and in some older people, absorption can be impaired despite a correct diet. Some commonly used medications also affect this vitamin's metabolism. This is one of the reasons why B12 deficiency isn't assessed by comparing a diet with a reference table.
Serum B12 measurement alone can be unreliable — a result within the normal range doesn't rule out cellular deficiency, which is why diagnostics also draw on methylmalonic acid and homocysteine. If you follow a plant-based diet or belong to one of the groups mentioned above, agree the form and dose of supplementation, and the scope of testing, with a doctor or dietitian.
Where to find it
meat · fish · eggs · dairy products · fortified foods
This material is for information and education. It does not replace advice from a doctor or dietitian. For health matters, consult a qualified medical professional.