Vitamin B12 – Everything You Need to Know

Whenever we do something about meat, the discussion turns to vitamin B12. And half-truths are always thrown around. Stop it!

What do we need vitamin B12 for?

Vitamin B12 is a so-called “coenzyme” . This means it is part of an enzyme that controls reactions in the human body. In this way, vitamin B12 helps in cell division and differentiation, the synthesis and modification of DNA, as well as in various processes in the metabolism of fats and amino acids, the building blocks of proteins.

For those interested in the details: Vitamin B12 helps convert homocysteine ​​(an amino acid that does not occur in proteins) into methionine. This amino acid is absolutely necessary for building proteins. However, we cannot make them ourselves. That is why this chemical reaction is so important.

By the way, B12 works together with folic acid, another important B vitamin.

Which foods contain vitamin B12?

First things first: Only foods of animal origin contain (in significant amounts) vitamin B12, which humans can absorb and use.

The B12 is produced by microorganisms – mostly bacteria, partly archaea. Never heard of Archaea? Doesn’t matter: Together with eubacteria and eukaryotes with a cell nucleus (that’s us), archaea form the three major domains of living things. They are also called archaea, but differ in many properties from the better-known eubacteria.

Animals absorb B12 in a variety of ways. People benefit from this when they consume animal products. In addition to meat, fish and seafood, this goes well with eggs and dairy products . In this way, many vegetarians can maintain their vitamin B12 balance.

You often hear about vitamin B12 in plant foods such as algae. Sometimes also from B12 in mushrooms. And indeed, some of them contain a vitamin B12 – albeit an analogue that humans cannot absorb and use as a coenzyme. Because vitamin B12 is not just vitamin B12. There are different varieties .

Why are there different types of vitamin B12?

Vitamin B12 is also called cobalamin . Behind it are several chemical compounds that all have one structure in common: a corrin ring system with a cobalt ion in the middle, which is responsible for the naming.

For those who don’t immediately flinch at chemistry:

A corrin ring is a complex made up of carbon rings. The carbons (C atoms) form so-called pyrrole rings, which in turn are connected to one another. The corrin ring differs from other rings in that the pyrrole rings are hydrogenated (i.e. have bonded H atoms). Also, two of the rings have a direct CC connection.

“Various chemical side chains can be bound to the cobalt ion,” explains graduate ecotrophologist Silke Restemeyer, nutritionist at the German Society for Nutrition e. V. (DGE). “That determines whether the vitamin B12 is usable for humans or whether they are analogues.”

Such B12 variants can be found in algae or even sauerkraut , but they may even have negative effects on people , according to the expert: “These analogues can attach themselves to the transporter systems in the cells and block them.” This is how the helpful B12 gets no longer so efficiently to the places where it can work.

There are various supplements available on the market

Some of the usable vitamin B12 compounds found in animal products include methylcobalamin and adenosylcobalamin, which the body can use immediately. Another natural vitamin B12 is hydroxycobalamin. It is not absorbed as well as methyl and adenosylcobalamin, but can be stored very well by the body.

In comparison, cyanocobalamin hardly occurs naturally. Because it’s inexpensive, it’s often synthesized and used as a dietary supplement, and it’s safe to take on a daily basis. Although cyanocobalamin must first be converted in several steps in the body, it is then a very stable version of B12.

For most people it makes no difference which of the three types is used. Methylcobalamin as the cheapest alternative to synthetic B12 is perfectly okay. There can be exceptions if you have certain genetic changes, but in this case you can only try different preparations anyway until you find the form or combination that helps.

Where do animals get vitamin B12 from?

This question depends on the animal:

Carnivorous animals, such as dogs and cats, do it just like us humans. You get vitamin B12 from animal foods .

Ruminants such as cattle and sheep have a so-called rumen: a forestomach with a distinctive flora of microorganisms. There are also many protozoa that can produce vitamin B12. To do this, however, the ruminants must have enough cobalt at their disposal, which is necessary for the synthesis. The vitamin B12 and other B vitamins are then flushed to the intestines and absorbed there.

Vitamin B12 producers are located in the large intestine

With horses, things seem even simpler, explains Prof. Ingrid Vervuert, Acting Head of the Institute for Animal Nutrition, Nutritional Damage and Dietetics at the University of Leipzig. The vitamin B12 producers are located in their large intestine, where they produce B vitamins that the horse can absorb. Unlike cattle and sheep, this works even with very low-cobalt feed.

Even rabbits can easily get vitamin B12. On the one hand, they have a very large intestine, whose bacterial culture provides enough B vitamins. In addition to the normal intestinal outlet, they also have a connection to the appendix – and eat the so-called appendix feces, which is rich in vitamin B12, other vitamins and proteins.

Vitamin B12 must also be added to some animals

It is more complicated with pigs, according to Ingrid Vervuert: “Apart from milk, eggs and fishmeal, no animal products may be fed to pigs. As a result, the normal feed spectrum for pigs is poorer in vitamin B12.” This is why vitamin B12 is added to the feed of these animals , as is the case with poultry – for the same reasons.

Fish are also a good source of vitamin B12. But where do they get the vitamin from? As with mammals, there is no one-size-fits-all answer. It has been shown, for example, that some freshwater fish produce B12 themselves – with the help of the bacteria in their intestinal flora. Other fish have to get it from their food.

For a long time it was believed that the main producers of vitamin B12 in fresh and sea water were cyanobacteria. As plankton, they serve as important food for the fish. But a few years ago, scientists found that cyanobacteria actually make an unusable B12 analogue. However, there are other bacteria and archaea in the water that provide the fish with vitamin B12.

What happens with vitamin B12 deficiency?

Nothing for years, as Prof. Hans Konrad Biesalski explains. “There are B12 stores in the body that provide us with the vitamin for years, even if we don’t eat enough of it,” says the nutritionist and author.

Homocysteine ​​concentration in the blood increases

However, this also means that it is often only years later that you notice if you are not taking in enough vitamin B12. What then happens: The homocysteine ​​can no longer be processed into methionine and the homocysteine ​​concentration in the blood rises .

“If the deficit lasts longer, cell division is disrupted. As a result, under certain circumstances, not enough blood cells can be formed,” says Silke Restemeyer. In addition to anemia, a B12 deficiency can lead to psychological problems, including poor memory, fatigue, attention deficit and depressive moods. Neurological symptoms can also occur, such as motor or sensory disorders.

How can you recognize a B12 deficiency?

The body can store large amounts of vitamin B12. It is therefore possible that a deficiency is only noticed years after the beginning of the undersupply, when the body’s storage is empty. Then it can lead to very different mental and physical abnormalities :

• anemia
• amnesia to the point of dementia
• fatigue
• depressive moods
• shortness of breath
• fainting
• dizziness
• low blood pressure
• movement coordination disorders
• increased tendency to fall
• cramps
• trembling of the hands
• tingling skin
• blurred vision
• lack of concentration
• hyperpigmentation

What are the causes of a B12 deficiency?

There are various causes of a B12 deficiency: Either the body is not supplied with enough B12 through food or the body cannot properly utilize the supplied B12 . Increased consumption or loss of vitamin B12 can also cause the vitamin B12 level in the blood to drop.

Not only a vegetarian or vegan diet can lead to undersupply – even if it is probably the most frequently discussed in this context. Inflammatory bowel disease and partial removal of the bowel , kidney disease and a lack of the protein intrinsic factor can also lead to a vitamin B12 deficiency.

Binding to the protein intrinsic factor, which serves to absorb cobalamin, is necessary for the absorption of B12 from food into the intestinal cells. Drugs that inhibit the formation of gastric acid can also cause B12 deficiency.

Which groups of people have a high risk of vitamin B12 deficiency?

People who eat a purely plant-based diet without supplementing vitamin B12 have an increased risk of B12 deficiency. But they are not the only ones: Patients with gastrointestinal diseases , including inflammation of the oral mucosa, also have an increased risk of a deficiency. These include, for example, people with chronic inflammatory bowel diseases such as Crohn’s disease, with diseases of the pancreas or people from whom parts of the stomach or intestines have been removed.

Pregnant women, breastfeeding women, people with autoimmune diseases, anorexics and the elderly are also among the risk groups and should make sure they get enough vitamin B12.

What can be done against vitamin B12 deficiency?

The different types of vitamin B12 deficiency give an idea: It is not enough for everyone to simply swallow a vitamin B12 capsule every day . Because if the absorption via the intestine is disturbed, these also only help to a limited extent. In the event of a deficiency, it is therefore essential to clarify with a doctor where the causes lie.

People with an acute deficiency – if symptoms are already appearing – must be treated as quickly as possible in any case. Because some symptoms can no longer be completely reversed. Patients who eat a vegan diet, for example, initially take high doses in capsule form every day. After 3-4 months, a lower dose should be sufficient.

Older people and those with a possible absorption disorder are given an injection into the muscles every 1-2 days for the first week . Hydroxy-B12 or cyano-B12 are suitable for this. Later, weekly to monthly injections will suffice.

B12 nasal spray can help

With children, it depends on the age and the circumstances, but here, too, the hydroxy- or cyano-B12 is injected into the muscles first of all if there are symptoms. Later, capsules or B12-enriched milk can be used. Treating the mother can help if the child is still breastfeeding and the breast milk is low in B12—that is, if the mother herself was B12 deficient.

In recent years, studies have shown that a vitamin B12 nasal spray is also safe for adults and provides sufficient intake of B12. In 2019, Dutch researchers published a study that also examined the nasal spray in children – with success, but with few study participants: inside. Especially as an alternative to injections into the muscles, this would be a great relief for the children.

What is the daily requirement of vitamin B12?

The estimated value of the German Society for Nutrition e. V. (DGE) for an adequate intake is 4.0 micrograms per day for young people from the age of 13 and adults.

For classification: 100 grams of mountain cheese contain about 0.81 micrograms of B12, salmon with a high content of 2 to over 3 micrograms per 100 grams and cooked roast beef even 4.5 micrograms per 100 grams.

Estimates of adequate intake of DGE start at 0.5 micrograms per day for infants and increase steadily with age to 4.0 micrograms. There are even higher recommendations for pregnant women (4.5 micrograms) and breastfeeding women (5.5 micrograms).

Recommendations are not uniform

If you look at the recommendations of the World Health Organization (WHO), the values ​​are significantly lower. For adolescents from the age of 13 and adults, the WHO proposes a guideline value of 2.4 micrograms per day. Even in pregnancy and in breastfeeding women, the values ​​are not much higher at 2.6 micrograms and 2.8 micrograms per day.

It doesn’t matter which values ​​you want to stick to: you don’t have to stand in the kitchen with the scales. Those who consume animal products in moderation usually do not need to worry about a deficiency – with exceptions.

As far as is known, too much vitamin B12 is not harmful . Nevertheless, not everyone should simply take B12 tablets as a precaution. Anyone who belongs to the risk groups mentioned in question 5 or has concerns can have their B12 status tested.

Can you test your vitamin B12 status at home?

There are several ways to determine vitamin B12 status. The total vitamin B12 and the holo-transcobalamin (active B12) are often determined in a medical laboratory. The homocysteine ​​values ​​can also be determined, but these are also influenced by other factors and are therefore not necessarily helpful.

The measurement of methylmalonic acid (MMA) in the urine provides the most accurate indication of the B12 status.

Better to ignore internet tests

Tests are offered on the Internet with which you can check your vitamin B12 balance. For example, you should send a drop of blood to the laboratory with the test kit and the results will be sent digitally. That sounds uncomplicated at first, and after all, the evaluation takes place in a laboratory.

On the one hand, one does not know whether they have been scientifically tested . On the other hand, the interpretation of the values ​​is not as easy as one might imagine. The “normal range” for total vitamin B12 determination is very large, ranging from 200 nanograms per liter (ng/l) to 1,100 ng/l. If a test delivers values ​​that are below or above, you should talk to a doctor anyway – after all, it must then be clarified what the deviation really is.

Diseases that cause the vitamin deficiency can only be recognized by the doctor

“If you buy a test on the Internet, the next step is probably to buy the tablets,” Biesalski suspects. But that may not help at all for some people. Apart from that, there are indications that even higher values ​​of around 400 ng/l can indicate a deficiency.

In cooperation with the family doctor or a nutritionist, such questions can be clarified much better than with a self-purchased test kit. In the case of vegan children, you should definitely speak to the pediatrician, who will then also carry out the B12 tests.

There is another benefit of going to a doctor with your questions about vitamin B12: In the event of a B12 deficiency, the health insurance companies may cover the costs for the tablets.