Vitamin B12

Carola Felchner is a freelance writer in the medical department and a certified training and nutrition advisor. She worked for various specialist magazines and online portals before becoming a freelance journalist in 2015. Before starting her internship, she studied translation and interpreting in Kempten and Munich.

More about the experts All content is checked by medical journalists.

Vitamin B12 (cobalamin) is the only water-soluble vitamin that the body can store for several years. It does this mainly in the liver. Among other things, vitamin B12 is important for the formation of red blood cells. Read more about the topic here: What is vitamin B12 good for? How Much Vitamin B12 Do You Need?

What is Vitamin B12?

Vitamin B12 is one of the B vitamins. Cobalamin, as it is also called, has to be actively channeled into the body through the mucous membrane cells in the intestine. A special protein, the so-called intrinsic factor, is necessary for vitamin B12 absorption. It is produced by the gastric mucosa and enters the intestine together with the food pulp.

The body can store vitamin B12 for several years, especially in the liver.

One name for multiple connections

The term vitamin B12 does not stand for a single chemical substance, but for several compounds with the same biological effect. These cobalamins are produced exclusively by bacteria (and blue-green algae). They accumulate naturally in animal products (such as liver, meat, eggs, dairy products). Vitamin B12 is also found in microbially produced foods such as sauerkraut.

What are the tasks of vitamin B12 in the body?

Vitamin B12 influences a number of important processes in the body. Particularly noteworthy is the vitamin B12 effect for:

• cell division and differentiation, for example in the formation and maturation of red blood cells
• the structure of the nerve cells in the spinal cord
• many reactions in protein and nucleic acid metabolism

Some celebrities swear by vitamin 12 for another reason - lose weight. When injected in high concentration, it is said to stimulate the metabolism. However, it has not been scientifically proven that this actually causes the pounds to drop.

Vitamin B12: daily requirement

How much vitamin B12 you need daily varies from person to person. The daily intake recommended by the German Nutrition Society (DGE) depends, for example, on age. Pregnancy and breastfeeding also influence the vitamin B12 requirement.

This is how much vitamin B12 you should consume according to the DGE:

age	Vitamin B12
	µg / day
baby
0 to under 4 months	0,5
4 to less than 12 months	1,4
children
1 to under 4 years	1,5
4 to under 7 years	2,0
7 to under 10 years	2,5
10 to under 13 years	3,5
13 to under 15 years	4,0
Teenagers and adults
15 to under 19 years	4,0
19 to under 25 years	4,0
25 to under 51 years	4,0
51 to under 65 years	4,0
65 years and older	4,0
Pregnant women	4,5
Breastfeeding	5,5

Vitamin B12: foods high in content

You can find out more about vitamin B12 levels in meat, fish, dairy products, etc. in the article on foods with a high vitamin B12 content

How does a vitamin B12 deficiency manifest itself?

How a deficiency in vitamin B12 arises and what consequences it can have can be read in the article Vitamin B12 deficiency

How does a vitamin B12 overdose manifest itself?

You can hardly absorb too much vitamin B12 because the body does not absorb unnecessary amounts through the intestinal wall. In addition, if the vitamin B12 dose is too high, it can excrete the excess through the kidneys.

An overdose of vitamin B12 is possible with:

• Liver metastases
• acute or chronic inflammation of the liver (hepatitis)
• Excessive intake of vitamin B12 by the doctor (e.g. as an injection)
• leukemia
• Polycythemia vera (pathological increase especially of the red, but also of the white blood cells)

Usually, vitamin B12 from foods has no side effects. Vitamin B12 intake in the form of injections or infusions can, however, in rare cases trigger an allergic shock. In the case of hypersensitivity, side effects very rarely occur even with external use (e.g. eczema or hives).

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