Vitamin B12 - the building blocks for strong nerves and healthy DNA

Vitamin B12 Nutrients

What is vitamin B12?

Vitamin B12 refers to a whole group of vitamins, the cobalamins, which are each built around a central cobalt atom.

Despite its low solubility, it belongs to the group of water-soluble vitamins and is an essential vitamin because the body cannot produce it itself. For this reason it must be obtained daily from food.

Why is vitamin B12 so important?

micronutrients vitamins for a healthy diet

Vitamin B12 is mainly involved as a coenzyme in processes of protein metabolism in the human organism. These include:

  • DNA and RNA synthesis (genetic material)
  • Cell division, growth and function
  • Formation of myelin sheaths (protective covering of nerve fibres)
  • Folic acid (vitamin B9) metabolism

Vitamin B12 ensures strong nerves and the production of DNA

Daily vitamin B12 requirement (in mg/day)*

Age Male Female
Young people 15 to under 19 years 4,0 4,0
Adults 19 to under 25 4,0 4,0
Adults 25 to under 51 years 4,0 4,0
Adults 51 to 65 years 4,0 4,0
Adults >65 years 4,0 4,0
Pregnant women 4,5
Breastfeeding 4,5

* D-A-CH reference values for nutrient supply, 1 edition 2015

Which foods contain a lot of vitamin B12?

Vitamin B12 is produced by microorganisms and is therefore only found in animal foods:

  • It is found in particularly large quantities in liver.
  • Followed by fish;
  • Eggs
  • Milk
  • and Cheese
  • Algae also produces large quantities, but its bioavailability varies

Algae products are a good substitute for vegans.

Vitamin B12 deficiency: symptoms and effects

sick woman sitting on a chair, drinking tea

Healthy people usually do not have to worry about having a vitamin B12 deficiency

However, under certain conditions you need to pay special attention to make sure you are getting an adequate supply.

Symptoms of vitamin B12 deficiency

Symptoms only appear after years of having a deficiency. This is due to the fact that the liver in the human organism has large stores that can cover our needs for up to 3 years. If there is a long lasting deficiency, the following symptoms can occur:

  • Tiredness and paleness: Triggered by a special form of anaemia (pernicious anaemia = vitamin B12 deficiency anaemia)
  • Increased bleeding tendency: Due to reduced platelet count
  • High susceptibility to infections + weakness of the immune system: due to low formation of white blood cells
  • Smooth red tongue, burning tongue
  • Frequent injuries of the mucous membrane
  • Loss of appetite and consequently weight loss
  • Impairment of the nervous system: tingling sensation in hands, feet and limbs, sensory disturbances, movement restrictions → with progressive deficiency: gait insecurity + paralysis
  • Dementia-like confusion and depression: By acting on the nerves and producing chemical messengers
  • Psychological symptoms: anxiety, hallucinations, delusions

Causes of a B12 deficiency

By absolutely abstaining from meat (as is the case with vegetarians or vegans), it can lead to a deficiency. However, these two risk groups are usually well informed on this topic, and, for the most part, optimally supplied by the variety of vegetarian and vegan substitutes.

Another risk group is people with stomach, intestinal or pancreatic diseases. In these cases, the internal component cannot be sufficiently produced. This is needed so that the vitamin B12 obtained from food can also be absorbed into the cells. If it is missing, a deficiency occurs.

In addition, people with an increased vitamin B12 requirement, such as pregnant women and breastfeeding mothers, should also make sure that they are getting an adequate supply. Smokers, alcoholics and people under a lot of stress can also develop a deficiency.

In summary, the following groups are at risk of a vitamin B12 deficiency:

  • Vegetarians + Vegans
  • People with diseases of the stomach, intestines, pancreas
  • Pregnant women + nursing mothers
  • smokers, alcoholics, people under great stress

Complaints that may occur in affected people could be disorders of muscle and nerve functioning.

Conclusion - What you should know about vitamin B12

Healthy people who eat a balanced diet and do not belong to any of the above-mentioned risk categories are unlikely to suffer from a vitamin B12 deficiency. Even occasional consumption of meat, milk, dairy products and eggs can be sufficient to counteract a deficiency.

If you would like to learn more about other vitamins, take a look at our Nutrients section!

Frequently asked questions and answers

No, even an extreme excess is not harmful to your body and will not cause discomfort. Vitamin B12 that the body does not need is simply excreted via the kidneys.

However, high-dose injections often lead to acne, which disappears when you stop taking it. The reasons for this are not yet sufficiently clear.

Exclusively in animal foods such as meat, meat products, milk, dairy products and eggs.

The vitamin is mainly involved in processes as a coenzyme:

  • DNA and RNA synthesis (genetic material)
  • Cell division, growth and function
  • Formation of myelin sheaths (protective covering of nerve fibres)
  • Folic acid (vitamin B9) Metabolism


Deutsche Gesellschaft für Ernährung. (2020). Nährstoffzufuhr über Supplemente. In 12. Ernährungsbericht 2012 – Kapitel 1 – Ernährungssituation in Deutschland. Zugriff am 18.06.2020 unter

Deutsche Gesellschaft für Ernährung, (2020). Referenzwerte für die Nährstoffzufuhr. Zugriff am 18.06.2020 unter

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