Vitamin B12 deficiency

A lack of vitamin B12 is relatively common. Vitamin B12 has a very long half-life by nature, which means that a deficiency only becomes apparent after several years. As a rule, a slight vitamin B12 deficiency is therefore not noticeable.

Only a longer or more severe deficiency then also appears with symptoms. Reserves of vitamin B12, which are mainly stored in the liver, heart muscle, skeletal muscle and brain, can be sufficient for the body for 2-3 years without being supplied. After that, a vitamin B12 deficiency and its consequences would occur.

Typical causes of a vitamin B12 deficiency are In order to understand why stomach diseases in particular can lead to a vitamin B12 deficiency, it is important to look into its absorption process. Vitamin B12 is absorbed in the small intestine (terminal ileum) by means of a transport protein, the so-called intrinsic factor. This intrinsic factor is produced in the stomach by special stomach cells (parietal cells) and then released into the small intestine, where it forms a complex with vitamin B12 that enables the absorption of vitamin B12.

If, as a result of a gastric resection, chronic gastritis or autoimmune disease, the production of vitamin B12 is reduced and a deficiency of intrinsic factor occurs, vitamin B12 can no longer be adequately absorbed by the body. The consequence is a vitamin B12 deficiency with its typical symptoms. Resections of the small intestine and diseases of the small intestine such as celiac disease or Crohn’s disease can also lead to absorption disorders of vitamin B12.

Drugs such as the proton pump inhibitors omeprazole and pantoprazole have been shown to inhibit the formation of stomach acid, which also plays an important role in the absorption of vitamin B12. Therefore, these drugs can also lead to a vitamin B12 deficiency in the long term.However, the most common cause of vitamin B12 deficiency is older people over 60 years of age. This often goes undetected.

The cause is age-related stomach or intestinal atrophy. Ultimately, pregnant women and chronically ill people also have an increased risk of a deficiency due to their increased need for vitamin B12. They should therefore pay particular attention to a balanced diet.

A too small admission of Vitamin B12 over the food (for example with Veganern) or over the intestine
Stomach diseases (can also lead to a reduced absorption of vitamin B12)
Drugs
A chronic severe alcohol abuse

For the absorption of vitamin B12 in the small intestine, enzymes and transport proteins are necessary, which are formed in the stomach. Vitamin B12 must be bound to the so-called “intrinsic factor” in the stomach in order to be absorbed in the small intestine. Patients who have had a gastrectomy due to stomach cancer then live without a stomach and therefore can no longer produce intrinsic factor, which leads to vitamin B12 deficiency if this factor is not replaced.

Vitamin B12 is absorbed in the ileum, the end section of the small intestine. Patients who have had this section of the intestine removed due to cancer also suffer from vitamin B12 deficiency if it is not corrected by vitamin B12 injections. In addition, patients with cancer are at greater risk of developing vitamin B12 deficiency due to the chronic disease, which causes a higher metabolic rate, because they have a higher requirement.