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Vitamin B12 (cobalamin)

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What is vitamin B12?

Vitamin B12 is a water-soluble vitamin from the group of B vitamins. The medical name is cobalamin. In food supplements, you should avoid products with the ingredient cyanocobalamin. This form of vitamin B12 is inactive and not particularly bioavailable. Instead, take methyl- and adenosylcobalamin.

What are the functions of vitamin B12?

The function of vitamin B12 in the nervous system stands out. Vitamin B12 is important in the breakdown of certain fatty acids and, like vitamin B9, is also relevant in methyl metabolism. Vitamin B12 is also involved in the production of SAM (S-adenosylmethionine). Cobalamin is also involved in blood formation and in the breakdown of certain amino acids, which can then be used to generate energy.

What makes vitamin B12 unique?

Although vitamin B12 is only involved in two enzymatic reactions as far as we know, the importance of the vitamin is high. This may be related to its influence on methyl metabolism. However, its importance for the CNS has still not been conclusively clarified. Only the serious deficiency symptoms indicate the importance of the vitamin.

How much vitamin B12 do you need per day?

According to the German Nutrition Society (DGE), estimates for an adequate vitamin B12 intake are as follows:

Age VitaminB12 µg/day
Infants
0 to under 4 months 0,5
4 to under 12 months 1,4
Children and teenagers  
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
15 to under 19 years 4,0
Adults  
19 to under 25 years 4,0
5 to under 51 years 4,0
51 to under 65 years 4,0
65 years and older 300
Pregnant women 4,5
Breastfeeding 5,5

When do you need vitamin B12 most?

If SAM is deficient and the antagonist homocysteine is elevated, this can be an indicator of inflammatory diseases such as arteriosclerosis. Methylcobalamin can help to provide methyl groups. Vitamin B12 is also required for learning or similar, as this is where memory is active. The need for vitamin B12 should not be underestimated in the case of anaemia. Often only iron is given here instead of a combination preparation that contains all the important factors.

How does an vitamin B12 deficiency develop and how does it manifest itself?

A vitamin B12 deficiency is associated with serious neurological damage that can affect concentration, nerve conduction speed, sense of touch, reflexes, movement and memory. Blood formation is also impaired, which can lead to anemia. Possible signs of a vitamin B12 deficiency can include hair loss, tiredness and muscle weakness. As vitamin B12 is only found in animal foods in relevant quantities, vegans and vegetarians are particularly affected by a deficiency. However, chronic inflammatory bowel disease, anorexia and chronic kidney or liver disease can also contribute to a deficiency.

What happens if there is an overdose of vitamin B12?

It is virtually impossible to absorb excessive amounts of vitamin B12 through food, as the excess is not absorbed or excreted. The Federal Institute for Risk Assessment (BfR) recommends a maximum amount of 25 µg vitamin B12 per day for food supplements. Overdosing can lead to health problems such as dizziness, vomiting, diarrhea and skin rashes. Persistent overconsumption can lead to damage to the nervous system.

Which foods are particularly high in vitamin B12?

Liver and kidneys contain by far the most vitamin B12. Fish, as well as small amounts of cheese and egg yolk, also contain vitamin B12. The vitamin is hardly present in plants. Traces can be found in soy, tempeh and ginger. There are indications that algae could also be a good source of vitamin B12, but there are no human studies to confirm its bioavailability. For vegans, vegetarians and people who do not regularly consume offal, an adequate supply of vitamin B12 is rather critical. A high-quality dietary supplement may therefore be advisable under certain circumstances.

Further blog articles on the topic

What vitamins are there and what do they do in your body?
Vitamins are vital substances for your body. You need them to maintain all your bodily functions; without them, your body would not be able to perform or survive. In this article, we will start by introducing you to these vital substances and going into more detail about the functions of the vitamins. We even need two parts for 13 vitamins. Here in Part 1 you will find everything about the fat-soluble vitamins A, D, E and vitamin K2.
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What are the functions of water-soluble vitamins?
Having already dealt with the fat-soluble vitamins A, D, E and K2 in Part 1, the water-soluble vitamins, which are in no way inferior to the fat-soluble vitamins, are still missing. What functions do B vitamins and of course the well-known vitamin C have? Find out more in part 2 on vitamins.
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Why are vitamins & co. so important for athletes?
How much importance should be attached to special nutrition for athletes? Why do athletes need more nutrients? Here you can find out more about the macro and micronutrients you need as an endurance or strength athlete.
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Vitamin B1 (thiamine)
What is vitamin b1, what function und effect does it have on your well-being?
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Vitamin B2 (riboflavin)
What is vitamin B2, what function and effect does it have on your well-being?
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Vitamin B5 (pantothenic acid)
What is vitamin B5, what function and effect does it have on your well-being?
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Vitamin B6 (pyridoxine)
What is vitamin B6, what function and effect does it have on your well-being?
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Vitamin B7 (biotin)
What is vitamin B7, what function and effect does it have on your well-being?
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Vitamin B9 (folic acid/folate)
What is vitamin B9, what function and effect does it have on your well-being?
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This dictionary entry is based on carefully researched sources:

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