Vitamin B12

Facts & Recommendations

Vitamin B12 (also called Cobalamin) is, like folic acid, a water-soluble B-vitamin. This vitamin exists in different forms, the naturally occurring methylcobalamin, adenosylcobalamin and hydroxycobalamin as well as the synthetic cyanocobalamin.

Clinical studies have shown that all forms of vitamin B12 improve the vitamin B12 levels.


The main sources of vitamin B12 are of animal origin: fish, meat, liver and to a small extent in dairy products and eggs.

For all those on a vegetarian/vegan diet or who eat little meat, the supply with this vitamin may prove to be difficult.


The bioavailability of vitamin B12 in humans with normal gastrointestinal function is estimated to be 50% depending on the nutritional source.


The water-soluble vitamin B9 is extremely light sensitive.
Vitamin B12, which is bound to protein in food, is released by the activity of the gastric juices in the digestive system and is  mainly absorbed in the small intestine. Vitamin B12 can be metabolized in the liver and in kidneys.


Vitamin B12, together with folic acid, plays an important role in DNA synthesis, as well as for proper blood cell formation and neurological function. Therefore, it is important during pregnancy to support the growth of the developing fetus.

Furthermore, vitamin B12 in combination with folic acid regulates the homocysteine level in the blood (homocysteine is a naturally occurring amino acid that is associated with cardiovascular diseases at high concentrations in the blood).

It is known that both vitamins, B12 and folic acid, should work “hand in hand” and be available to the organism in sufficient amounts, especially before conception.

Vitamin 12 deficiency is common and increases with age (e.g. due to increased atrophic gastritis or pernicious anemia).

For pregnant women who are vegans or vegetarians and women with pernicious anemia or malabsorption syndromes such as Crohn’s disease or celiac disease, the greatest risk of deficiency is considered.

What is pernicious anaemia?

Pernicious anemia is an autoimmune disease that affects the gastric mucosa, resulting in no intrinsic factor being produced, resulting in vitamin B12 malabsorption. If left untreated, it causes vitamin B12 deficiency.

Consequences of a vitamin B12 deficiency

A vitamin B12 deficiency includes neurological changes, chronic fatigue, megaloblastic anemia, digestive disorders and cardiovascular diseases.

Deficiency in pregnant women is associated with placenta-related complications such as preeclampsia and foetal growth restriction, neural tube defects (NTDs), increased risk of premature delivery, as well as postnatal depression.


Several studies have shown that:

  • Vitamin B12 is needed for fertility in men and women.
  • an adequate intake of vitamin B12 and folic acid before and during pregnancy was associated with a reduced risk of NTDs, as well as other related disease that mainly occur in the first trimester.

The current recommendations for daily vitamin B12 supplementation during pregnancy and lactation are in the range around 3 µg. However, scientists insist that these intake recommendations be re-evaluated. The German Federal Institute of Risk Assessment (BfR) has recently increased the highest vitamin B12 concentration to be used in dietary supplements from 9 µg (2004) to 25 µg (2018).

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