Your best sources of vitamin B12

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Vitamin B12 in detail: Why it's important and where you can find it

Vitamin B12, also known as cobalamin, is released in the gastrointestinal tract and absorbed by a protein called intrinsic factor. This absorption occurs mainly in the lower part of the small intestine. A lack of intrinsic factor or problems with absorption can lead to a vitamin B12 deficiency.

What is intrinsic factor?
Intrinsic factor is a protein that is produced in the stomach and plays a crucial role in the absorption of vitamin B12 in the small intestine. Its main function is to bind the vitamin B12 contained in food and allow it to pass through the acidic stomach contents without being destroyed by stomach acid.

Here are the main steps of how the intrinsic factor works:

  • Production in the stomach: intrinsic factor is produced by the so-called parietal cells of the gastric mucosa. These cells also produce gastric acid (hydrochloric acid), which is necessary for the activation of the intrinsic factor.
  • Binding to vitamin B12: In the stomach, the intrinsic factor forms a bond with the ingested vitamin B12. This bond protects the vitamin from stomach acid and enables it to reach the small intestine undamaged.
  • Absorption in the small intestine: In the lower part of the small intestine, in the so-called ileum, the intrinsic factor continues to bind to the vitamin B12 and thus promotes its absorption into the bloodstream. This process is crucial for supplying the body with sufficient vitamin B12.


It is important to emphasize that a lack of intrinsic factor can lead to poor absorption of vitamin B12, even if sufficient amounts are present in the diet.

Can I stimulate the production of intrinsic factor in the parietal cells?
The production of intrinsic factor by the parietal cells in the stomach is influenced by various factors. Here are some of the most important influencing factors:

  • Gastrin: Gastrin is a hormone that stimulates gastric acid production and promotes parietal cell activity, including intrinsic factor production. The release of gastrin is triggered by food intake and the stretching of the stomach.
  • Histamine: Histamine is a substance that supports acid production in the stomach and also influences the release of intrinsic factor. Histamine is released by certain cells in the stomach and interacts with receptors on the parietal cells.
  • Vitamin B12 requirement: Paradoxically, the need for vitamin B12 can also influence the production of intrinsic factor. A low vitamin B12 level can stimulate the parietal cells to produce more intrinsic factor in order to increase the absorption of vitamin B12.
  • Autoimmune reactions: In some cases, an autoimmune reaction against the parietal cells can lead to a lack of intrinsic factor. In such cases, antibodies are produced against the parietal cells, which can impair the production of intrinsic factor.

It is important to emphasize that the exact regulation of intrinsic factor production is complex and depends on individual genetic and physiological factors. Autoimmune diseases, certain medications or other conditions can affect intrinsic factor production.

If there are signs of vitamin B12 deficiency and concerns about intrinsic factor, an accurate diagnosis by a healthcare provider is necessary. In cases where intrinsic factor deficiency is present, treatment usually involves vitamin B12 injections or high-dose oral supplements to ensure normal vitamin B12 absorption.

Once absorbed, vitamin B12 is activated in cells by specific enzymes to perform its various functions. It interacts with other B vitamins such as folic acid to keep the metabolic process running properly.

Vitamin B12 deficiency

A lack of vitamin B12 can lead to anemia, as the production of red blood cells is impaired, and it can lead to neurological problems, as nerve cells are not sufficiently protected.

As the body cannot produce vitamin B12 itself, an adequate intake through diet or supplements is essential, especially for people who follow a vegan diet, as plant-based foods naturally contain little to no vitamin B12.

What functions does vitamin B12 have in the body?

  • Formation of red blood cells: Vitamin B12 contributes to the normal formation of red blood cells. Vitamin B12 is crucial for the formation of red blood cells in the bone marrow. These cells transport oxygen in the blood throughout the body and are essential for energy production.
  • Function of the nervous system: Vitamin B12 contributes to the normal function of the nervous system. Vitamin B12 plays an important role in the formation and protection of nerve cells. It is involved in the formation of the myelin sheath, a protective layer around the nerve fibers that is crucial for the efficient transmission of nerve impulses.
  • More energy: Vitamin B12 contributes to the reduction of tiredness and fatigue. Vitamin B12 contributes to normal energy metabolism. Vitamin B12 is necessary for your energy metabolism and plays an essential role in reducing tiredness and fatigue.

Which foods are high in vitamin B12?
Vitamin B12 is a crucial vitamin for various functions in the body, including the formation of red blood cells and supporting the nervous system. Here are some foods that are rich in vitamin B12:

  • 🫁Liver: liver, especially beef liver, is one of the best sources of vitamin B12. It contains high amounts of this vitamin as well as other important nutrients.
  • 🐟Fish: Seafood such as salmon, tuna and mackerel are excellent sources of vitamin B12. Sardines and trout are also good options.
  • 🥩Meat: Red meat, poultry and pork all contain vitamin B12. It's important to choose lean meat and prepare it properly.
  • 🥚Eggs: Eggs, especially egg yolks, contain vitamin B12. They are also versatile in the kitchen and can be prepared in different ways.
  • 🥛Dairy products: Milk, yogurt and cheese are good sources of vitamin B12. Make sure to choose low-fat options to control the total fat content.
  • 🥣Enriched foods: Some plant-based foods such as breakfast cereals, soy milk and energy bars are often fortified with vitamin B12.
  • 💊Food supplements: Supplements can contain vitamin B12. When buying them, look for products that are tailored to your needs.

A balanced consumption of these foods can help to cover your vitamin B12 requirements. It is important to note that vitamin B12 is mainly found in animal products and people on a vegan diet may want to consider supplements.

Vitamin B12 for vegans?
As this vitamin is mainly found in animal products, it can be a challenge for people on a purely plant-based diet to get sufficient amounts. Here are some vegan-friendly options:

  • 🥣Enriched foods: as mentioned above, some plant-based foods such as breakfast cereals, soy milk and energy bars are fortified with vitamin B12. Vegans should make sure to include these products in their diet.
  • 💊Food supplements: Vegan-friendly vitamin B12 supplements are widely available on the market. These supplements provide a reliable source of vitamin B12 and can be a useful supplement for people who have difficulty getting enough of it from food. Vegans should make surethat the products are tailored to their specific needs.
  • 🌿Algae: Some seaweeds and sea vegetables contain small amounts of vitamin B12. However, it is important to note that the form of B12 in algae is not as easily or not at all usable by the human body as that in animal products.

Vegans should pay particular attention to their vitamin B12 intake in order to avoid deficiency symptoms.

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