In which foods can vitamin B12 found and how can I best absorb it?

In all forums, articles and books about the vegan diet you can read that most vegans have a high risk of a vitamin B12 deficiency and should therefore supplement it. Why does it only affect vegans? In which foods can vitamin B12 be found? Does only meat contain vitamin B12?

Where does vitami B12 come from?

Vitamin B12 can only be synthesized by microorganisms such as bacteria. Herbivorous animals have these microorganisms in their gastrointestinal tract and are therefore able to feed their own cells with enough vitamin B12.

Since the synthesis of vitamin B12 works differently in various animals, we will explain the process using the example of the cow. Unlike humans, cows are ruminants. They chew the already pre-digested food mash several times before the actual digestion takes place. This enables them to process food components we cannot digest, such as fiber. This process takes place between the stomach and the rumen. The microorganisms that are able to synthesize vitamin B12 are located in the rumen. After the vitamin has been formed, it is transported via the blood to various cells, such as the muscles. The amount of the vitamin which is not used, is stored in the liver and other organs.

The human large intestine also contains the microorganisms to produce cobalamin itself. However, the absorption of vitamin B12 by the intrinsic factor takes place in the small intestine, which is located before the large intestine. Since the large intestine does not have the intrinsic factor required for absorption, the vitamin cannot be used and is immediately excreted.

Which products contain a particularly high amount of vitamin B12?

In addition to meat and innards, cheese and milk also contain vitamin B12. So, at least with a vegetarian diet, the vitamin intake should be sufficient. An overview of the vitamin B12 content in various foods can be found in the following table:

The intrinsic factor can facilitate the absorption of up to 2 µg vitamin B12 per meal. Therefore, the consumption of cheese or milk should be sufficient for a normal vitamin B12 status. Studies have shown that a continuous intake of vegetarian foods with a lower vitamin B12 content has a better influence on the vitamin B12 status than the consumption of B12-rich meat with relatively long interruptions. With a balanced diet, which contains both animal and vegetable products, the recommended daily intake of 4 µg for adults and adolescents aged 13 and above can be covered.

What is the intrinsic factor? And why do I need it?

The intrinsic factor is a transport protein that is formed in the gastric mucosa. In the stomach it forms a complex with the absorbed cobalamin and transports it to the small intestine. There both the protein and the vitamin are absorbed by the mucous membrane of the small intestine and thus get into the blood and are transported to the various cells.

In the case of gastrointestinal diseases or a reduced production of the intrinsic factor, a deficiency of vitamin B12 can occur despite high meat consumption and the associated high intake of vitamin B12.

When consuming various supplements, such as our Methyl B-12 lozenges, the vitamin is not absorbed via the intrinsic factor, but passive diffusion occurs via the oral mucosa. The intrinsic factor is not needed, but only 1 - 2% of the vitamin contained is absorbed. This is due to the compley structure of the B12 molecule. For this reason, most of the B12 dietary supplements have such a high content of vitamin B12.

Certain groups of people have an increased need for vitamin B12 or cannot reach the recommended daily intake and therefore they benefit from supplementation. For example, pregnant women, breastfeeding women, the elderly or people with hormonal changes as well as vegans can benefit from a supplementation of vitamin B12. After consulting a doctor, it should be decided whether the recommended daily requirement of 4 µg can be achieved through diet or whether supplementation is necessary.

Is there absolutely no way of absorbing vitamin B12 through plant-based foods?

There are many studies that allegedly prove that certain plant foods such as sea buckthorn juice, fermented soy products, wheat beer, root vegetables or sauerkraut contain a sufficient amount of vitamin B12. However, these assumptions are controversial and have not yet been scientifically proven. Most of these foods contain analogues that are chemically similar to vitamin B12, but do not have the same effect in the body.

Many studies also examined the vitamin B12 content in algae, especially Chlorella and Nori. However, they could not confirm a clear impact. Consequently, no clear scientific statement can be made about the content of B12 in algae. There are already attempts to enrich algae with vitamin B12 and thus achieve a higher content. Perhaps this could be a way of consuming vitamin B12 without animal foods in the future.

Presently, the best option for optimal vitamin B12 status is a regular check of the vitamin B12 level in the blood and based on this, an adequate supplementation.