Vitamin B12 deficiency symptoms: causes and therapy

Vitamin B12 Mangel Symptome: Ursachen und Therapie

Vitamin B12 is one of the super vitamins and is part of many essential processes in the human body. The lack of the vitamin usually only occurs after a few years, but can have serious consequences.

This article looks at the defect in the fabric and how to address it. In addition, other important questions about vitamin B12 are answered. The focus is on objective reporting and the topic is examined from all sides.

the essentials in brief

  • Humans have large stores of vitamin B12 and can function without problems for several years without taking the substance. However, when the deficiency sets in, the nervous system can be damaged.
  • To prevent a vitamin B12 deficiency, dietary supplements or a change in diet are suitable. The vitamin is present in both animal and plant foods.
  • Vitamin B12 can be taken as a preventive measure to ensure that the deficiency is ruled out. For a more precise procedure, you can seek advice from a doctor.

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What is vitamin B12?

Vitamin B12 is a very important vitamin. It plays a decisive role in metabolic processes and is considered an all-round talent among vitamins. B12 is a collective term for chemical compounds with the same basic structure. These compounds are also called "cobalamins".

Cobalamins play an important role in the nervous system, blood formation, detoxification and the breakdown of fatty acids. In addition, thanks to B12, folic acid is brought into a form that the body can use.

Due to the versatile functions of B12 and the importance of the vitamin, it has a major impact on the physical and emotional state of people.

Vitamin depletion can occur when more B12 is consumed than is being put into the body. However, the B12 stores are relatively large and can normally provide a person with sufficient B12 for a period of 3 to 5 years.

A study by the "Journal of Nutrition and Metabolism" examined how the vitamin B12 content in the human body behaves over a period of 13 years. No B12 was actively added to the participants during this period. After 13 years, the participants still had 50 percent of their original B12 levels in their bodies. (1)

What is the function of vitamin B12 in the body?

Vitamin B12 is part of many important functions in the body. For example, B12 affects:

  • Cell Division: Both cell division and differentiation are done in the formation and maturation of red blood cells with the help of B12.
  • The spinal cord: The structure of the nerve cells in the spinal cord can also be influenced by B12.
  • Metabolism: Many reactions in protein and nucleic acid metabolism are related to B12.

The vitamin is particularly important because the body cannot produce it itself. Cell function can be affected by a deficiency, which is why it is particularly important to prevent a deficiency. (2)

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What is the daily requirement of vitamin B12?

The daily requirement of vitamin B12 depends on various influencing factors. For example, age and life situation are decisive for the daily requirement of B12.

According to the German Society for Nutrition, the daily requirement of vitamin B12 is 4.0 µg for adults. Babies have a daily requirement of 0.5 µg. In adolescents, as in adults, the value is 4.0 µg. Pregnant women have an increased requirement of 4.5 µg and last but not least, breastfeeding women have a daily requirement of 5.5 µg.

gender/living situation Daily requirement of vitamin B12
baby 0.5 µg
children and young people 4.0 µg
Adult 4.0 µg
pregnant women 4.5 µg
breastfeeding 5.5 µg

An article in the scientific journal "American Family Physician" found that a daily oral intake of 1.0 mg of B12 corrects a deficiency as effectively as treating the deficiency intramuscularly. Increased amounts of B12 can also be consumed. (3)

What are the causes of vitamin B12 deficiency?

A lack of vitamin B12 can occur if the substance is not added to the body over a longer period of time or if more is consumed than the body has stored.

Likewise, increased consumption or loss of vitamin B can cause the level of B12 in the blood to decrease. There are also certain medications that promote B12 deficiency.

The main causes of vitamin B12 deficiency are summarized in the following list:

  • anorexia
  • strictly vegan/vegetarian diet
  • Lack of intrinsic factor (a protein produced in the stomach)
  • Disturbed vitamin B12 absorption in the intestine
  • increased consumption of vitamin B12
  • Medications such as omeprazole or meformin

Which foods contain vitamin B12?

In principle, most Germans are supplied with sufficient B12. This does not apply to vegans and vegetarians, as foods rich in vitamin B12 are almost exclusively of plant origin.

Sea buckthorn berries are the only plant-based food that contains vitamin B12.

Foods that contain a relatively large amount of vitamin B12 include:

  • eggs
  • Meat & offal
  • oysters
  • Fish
  • Cheese
  • sea ​​buckthorn berries
Groceries Vitamin B12 content per 100 grams
beef liver 65 mcg
oysters 14.5 µg
Rabbits 10 µg
herring 8.5 µg
Trout 4.5 µg
chicken egg 1.8mcg

Are Vitamin B12 Deficiency Symptoms Dangerous?

Vitamin B12 deficiency is a gradual process. The body has large stores and it takes a few years for them to be exhausted. Initially, a deficiency usually manifests itself in the form of anemia. This means that the body no longer produces enough red blood cells.

The consequences can be tiredness, pale skin, difficulty concentrating and memory problems. B12 deficiency symptoms also include tingling or numbness in the feet and hands.

Since the body has such large reserves, it usually takes a long time before a vitamin B12 deficiency becomes noticeable and visible in the blood count. This is where the danger lies. Irreparable damage to the nervous system can occur over a longer period of time until the B12 deficiency is covered again. Older people in particular are associated with memory loss and dementia with an undersupply of vitamin B12.

When should you go to the doctor for a vitamin B12 deficiency?

Basically, it is always advisable to consult a doctor in the event of a vitamin B12 deficiency. However, it is not always easy to identify a B12 deficiency. It can take several years for the deficiency to become noticeable in the blood count.

In order to counteract a vitamin B12 deficiency early, it makes sense to change your diet to B12-rich foods in good time or to supplement with vitamin B12 preparations.

You can meet with a doctor to take preventive measures against a possible deficiency. In this way you can reduce the risk of unpleasant symptoms or diseases in advance.

How does a vitamin B12 overdose manifest itself?

Since vitamin B12 deficiency can be so dangerous and the topic is being discussed more and more in the media, more and more people are making sure that their vitamin B12 needs are covered.

Consequently, it is possible that the vitamin can be overdosed due to too much fear or carelessness. While it is virtually impossible to overdose from foods containing vitamin B12, oral supplements are also very difficult to overdose on.

The only way to cause a vitamin B12 overdose is with a syringe at the doctor's. Physicians have the option of injecting B12 directly into the bloodstream. In this way, a large amount of the vitamin is immediately available to the body.

Symptoms of a vitamin B12 overdose are:

  • Pale skin
  • exhaustion
  • difficulty concentrating

Accordingly, there is usually no need to worry about a vitamin B12 overdose.

How can a vitamin B12 deficiency be treated?

A vitamin B12 deficiency can have many causes. Taking certain medications, anorexia, a vegan diet are all possible ways that a deficiency can be caused. Also, the intestines cannot function properly, which makes B12 absorption more difficult.

A tired man in an office rubs his face

A lack of vitamin B12 can manifest itself as a lack of concentration. Over a longer period of time, even the nervous system can be damaged. (Image source: / Dmitrii Shironosov)

There are two ways to combat a vitamin B12 deficiency. On the one hand, dietary supplements can be taken to increase the B12 content. On the other hand, the diet can be switched to foods rich in B12.

dietary supplements

The simplest and for most people the most sensible way to prevent or end a vitamin B12 deficiency is to take dietary supplements.

Vitamin B12 supplements come in many different forms and dosages. There are tablets, powder, drinking ampoules and injections administered by the doctor. The dosages vary greatly and depend on the preparation and the manufacturer of the product.

Woman takes vitamin pills

Vitamin B12 can be supplemented in the form of tablets. It should be noted that the dosages vary greatly between manufacturers. (Image source: / puhhha)

A big advantage of dietary supplements is that the amount of B12 contained is strictly controlled and the supply can be secured by quickly swallowing a tablet. The content of food can vary and certain foods must be consumed in a targeted manner.

change in diet

Changing your diet is another way to counteract a vitamin B12 deficiency. Animal foods in particular can cover the daily B12 requirement.

The disadvantage of this type of prevention is that the deficiency has to be counteracted with very specific foods. Foods such as beef liver contain the most B12, but are not eaten as regularly as, for example, chicken eggs. These also contain B12, but significantly less than the liver.

The change in diet is particularly suitable for people who do not like to take food supplements and prefer to absorb their nutrients through normal nutrition.


  1. Jansen E, Beekhof P, Stability of Folate and Vitamin B12 in Human Serum after Long-Term Storage: A Follow-Up after 13 Years J Nutr Metab. 2018; 2018: 9834181.
  2. The role of vitamin B12 in the critically ill--a review Anaesth Intensive Care . 2016 Jul;44(4):447-52.
  3. Langan R, Goodbred A, Vitamin B12 Deficiency: Recognition and Management by the Fam Physician. 2017 Sep 15;96(6):384-389.
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