Vitamin B12 is a water-soluble vitamin. It occurs in several forms within the body, but all referred to by the term cobalamin. This vitamin is special, since it is found exclusively in foods of animal origin (offal, meat, fish, eggs, royal jellies and dairy products). Thus, when the consumption of foods of animal origin is reduced, the dietary intake of vitamin B12 is reduced, requiring possible supplementation via food supplements. This is why every vegan-vegan must take supplements to stay healthy. This may also be the case for an individual adopting a vegetarian diet, as vitamin B12 levels are low in eggs and dairy products. Especially since the latter is destroyed in the light, reducing the initially low rates. Apart from food intake, a small endogenous source from the intestinal flora provides vitamin B12. Additionally, the body is capable of storing a small amount of vitamin B12, but the storage duration is extremely variable. It is therefore essential to ensure regular intake of vitamin B12, given that its deficiency is serious and should not be taken lightly. It is necessary for our physical and nervous health and it is involved in many vital processes. Adopting a diet that is as diverse and balanced as possible is essential to meet daily vitamin B12 needs.

  • Family: vitamins
  • Other name(s): cobalamin
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Calculate my daily requirement for Vitamin B12

I am :

In which foods can I find my daily intake of Vitamin B12?

Foods containing Vitamin B12 Vitamin B12 concentration (in mg/100 g) Quantity of food to cover my daily needs (in g)
Royal jelly 0.15 ?
Lamb kidney, cooked 0.0789 ?
Periwinkle, cooked 0.0607 ?
Lamb liver, cooked 0.06 ?
Calf liver, cooked 0.0526 ?
Chicken liver, cooked 0.0505 ?
Clam, cooked 0.0395 ?
Nori, dried 0.0388 ?
Octopus, cooked 0.036 ?
Ao-nori, dried 0.0306 ?

Properties of Vitamin B12

Vitamin B12 is studied and recognized for the following main properties:

  • Regulator of gene expression : Vitamin B12 will activate vitamin B9 (folic acid) so that it can act on DNA synthesis. Vitamin B12 is therefore an essential coenzyme in DNA expression.

  • Participating in the development of the nervous system : Vitamin B12 is involved in the synthesis and repair of myelin sheaths. Myelin sheaths are membranes surrounding nerve fibers (axons, more precisely).

  • Antianemic : Vitamin B12 is an essential vitamin for the formation of red blood cells. Indeed, it is involved in the maturation of red blood cells, the final phase of hematopoiesis (all the stages leading to the synthesis of red blood cells).

  • Contributing to energy metabolism : Vitamin B12 is involved in the conversion of succinyl-CoA. The latter is a metabolic player participating in the synthesis of glucose, fatty acids and the catabolism of certain amino acids (isoleucine, valine, threonine and methionine).

  • Anti-inflammatory : Vitamin B12 is involved in the homocysteine ​​cycle. It promotes the transformation of the latter into methionine. Homocysteine ​​is an amino acid with a pro-inflammatory capacity, which methionine, another amino acid, does not possess. Ultimately, vitamin B12 helps neutralize homocysteine.



The “vitamin B12” contained in certain plants (comfrey, algae, etc.) is in fact an analogous and inactive substance of vitamin B12. Having no vitamin activity in humans. Foods of plant origin cannot claim to meet vitamin B12 needs.

Vitamin B12, why is it important?

In case of moderate deficiency

Vitamin B12 deficiency can manifest itself in the following problems. In this case a sufficient intake or even supplementation is necessary.

  • Severe fatigue
  • Weight loss
In case of proven deficiency

A proven deficiency of Vitamin B12 is involved in the following situations. The advice of a healthcare professional is required.

  • Nausea
  • Spasms
  • Depression
  • Mood disorders
  • Digestive disorders
  • Memory problems
  • Glossitis
  • Circulatory disorders
  • Megaloblastic anemia
  • Intramedullary hemolysis
  • Leukopenia
  • Pancytopenia
  • Paresthesia
  • Growth retardation
  • Myelodysplastic syndrome
  • Thrombocytopenia
  • Gynecological disorders
  • Neurological disorders
  • Psychic troubles
  • Fetal malformation
In case of excess

Optimal intake of Vitamin B12 helps prevent the following situations:

Beneficial in prevention

Vitamin B12 is not toxic, even in massive doses. In case of excess, the body simply gets rid of it by eliminating it through urine and stools.

  • Cardiovascular pathology
  • Alzheimer's disease
  • Thromboembolic pathology

Choose your foods wisely

  • Opaque packaging: vitamin B12 is sensitive to light. Prefer food with opaque packaging upon purchase, to preserve the vitamin.

Food preservation and storage

  • À away from direct light: vitamin B12 is a photosensitive vitamin. Storing the food away from light helps maintain the vitamin.

Vitamin B12 and interactions

Negative effects

  • PPI medications: the mechanism of absorption of vitamin B12 is complex. In fact, it is found exclusively in protein-bound form in foods. It therefore needs gastric acidity (and pepsin, a protein enzyme) to be released from this protein and bind to intrinsic factor, an "agent" that protects vitamin B12 until it is absorbed into the body. ileum (intestinal area). Ultimately, stomach acid promotes its absorption. Antacid medications (IPP) will influence the absorption of vitamin B12.

  • Metformin: metformin, a hypoglycemic treatment, decreases plasma levels of vitamin B12.

  • The alcohol : chronic alcohol consumption reduces the absorption of vitamin B12.

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