Vitamin B12

What does vitamin B12 do in our body?

Vitamin B12 supports our body in various everyday processes. It contributes to normal energy-yielding metabolism, supports the normal functioning of the nervous system and contributes to normal psychological function.

In addition, vitamin B12 contributes to the normal formation of red blood cells, helps reduce tiredness and fatigue, and plays a role in homocysteine metabolism (the way the body converts and regulates homocysteine).

Vitamin B12 also supports the normal functioning of the immune system and has a role in the process of cell division. These are authorised health claims established under European food legislation.

How do vitamin B11 and vitamin B12 work together?

Vitamin B11 is a collective term for different forms of this vitamin. Folate is the form naturally found in food. Folic acid is the synthetic form used in food supplements and fortified foods.

Vitamin B11 and vitamin B12 each have their own functions, but they also work closely together in the body. Both are involved in converting homocysteine into methionine, a process that is important for normal cell division and DNA synthesis.

A good balance between these two vitamins is important. A high intake of folic acid can partially mask certain consequences of a vitamin B12 deficiency, such as anaemia. However, neurological symptoms caused by a vitamin B12 deficiency may still persist.

Read more about this in our article Combining food supplements: What works together and what doesn't?

Vitamin B12 in food

Vitamin B12 occurs naturally almost exclusively in animal-based foods, such as meat, fish, eggs and dairy products. Plant-based foods naturally contain very little vitamin B12. Fortified foods and food supplements can therefore be important sources of vitamin B12 for people following a plant-based diet.

Vegans in particular have an increased risk of not getting enough vitamin B12. Vegetarians may also consume too little vitamin B12 if they eat few dairy products, eggs, fortified foods or suitable food supplements.

However, it is not just the amount of vitamin B12 in your diet that matters. Absorption in the body can also be impaired. This may occur, for example, in older people with reduced stomach acid production, people taking metformin or acid-reducing medication for a long time, after stomach surgery or in certain intestinal conditions.

Read more about this in our article Food supplements and medication.

How does the body absorb vitamin B12?

Our body has a special system for absorbing vitamin B12. A protein called intrinsic factor is produced in the stomach. This protein binds to vitamin B12 and accompanies it through the digestive tract. In the final section of the small intestine, the vitamin B12 and intrinsic factor complex is recognised and absorbed.

If too little intrinsic factor is produced, for example due to certain stomach conditions, after stomach surgery or in pernicious anaemia, vitamin B12 absorption can be severely reduced.

There is also a second route of absorption called passive diffusion. Through this process, a small percentage of vitamin B12 is absorbed without the need for intrinsic factor. At low doses, this amount is small. At high doses, however, even this small percentage can become significant.

The body can also store vitamin B12 for several years, mainly in the liver. This means that a deficiency can develop slowly and may only become noticeable after months or years.

How can you recognise a possible vitamin B12 deficiency?

A vitamin B12 deficiency usually develops gradually. Possible symptoms associated with low vitamin B12 levels include:

• Fatigue
• Difficulty concentrating
• Tingling or numbness in the hands or feet
• Pale skin
• Mood changes

These symptoms are not specific to a vitamin B12 deficiency and may have other causes. You should therefore never assume you have a deficiency based on symptoms alone.

Can vitamin B12 levels be tested?

Vitamin B12 levels can be measured through a blood test. The most commonly used test measures vitamin B12 in the blood serum. However, this result does not always provide a complete picture.

If the results are unclear, a doctor may arrange additional tests, such as methylmalonic acid (MMA) or homocysteine. These can provide further information about a possible functional vitamin B12 deficiency.

When should you consult your GP?

Contact your GP if symptoms persist, if you have low vitamin B12 levels accompanied by symptoms, or if you experience neurological symptoms such as tingling, changes in sensation or balance problems.

You should also discuss your situation with your GP if you have known risk factors or suspect a vitamin B12 deficiency during pregnancy.

When might a vitamin B12 supplement be useful?

A food supplement may be useful, for example, if you follow a plant-based diet, as an addition to your daily diet or on the advice of a doctor or therapist.

If a vitamin B12 deficiency has been confirmed, it is important to identify the underlying cause first. A food supplement is not a substitute for medical treatment in cases of severe deficiency or neurological symptoms.

Why do food supplements often contain such high doses?

Reference values vary by country; in the Netherlands and much of Europe, the recommended daily intake for adults is 2.8 micrograms of vitamin B12. Nevertheless, food supplements often contain doses of several hundred to 1,000 micrograms or more.

This may sound like a large amount, but it actually represents a very small weight: 1,000 micrograms equals 1 milligram.

Other B vitamins are often measured in milligrams in food supplements. However, a direct comparison is not particularly useful because each vitamin has its own daily requirement. The requirement for vitamin B12 is especially low.

The reason why doses of 1,000 micrograms are commonly used is mainly related to how the body absorbs vitamin B12. Only about 1.5 to 2 micrograms can be absorbed through intrinsic factor during a single absorption process. Approximately 1% of the remaining amount enters the body through passive diffusion.

With a tablet containing 1,000 micrograms of vitamin B12, approximately 10 micrograms can therefore enter the body through passive diffusion.

Food supplement or injection?

An injection is not automatically better than a tablet. Clinical guidelines recommend tablets as the first choice in many situations, even when normal absorption is impaired.

This is because high oral doses of vitamin B12 can still be absorbed through passive diffusion.

Injections may be used in cases of severe neurological symptoms, very low vitamin B12 levels or when tablets do not provide sufficient results. The GP decides which treatment is most suitable in each individual situation.

What forms of vitamin B12 are available?

You may find different forms of vitamin B12 listed on the label of a food supplement.

• Cyanocobalamin is a commonly used and stable form. The body converts it into the active forms of vitamin B12.
• Methylcobalamin is one of the active forms of vitamin B12 and is often used in tablets, orally disintegrating tablets and lozenges.
• Adenosylcobalamin is the other active form and plays a role mainly in the mitochondria, where energy is produced at a cellular level.
• Hydroxocobalamin is another form of vitamin B12 and is mainly used for injections.

Some food supplements combine methylcobalamin and adenosylcobalamin.

Which form of supplement should you choose?

Vitamin B12 is available in several different forms. Which one suits you best mainly depends on how you prefer to take your supplement.

There is currently insufficient scientific evidence to suggest that one oral form is absorbed significantly better than another.

Capsules and tablets

Capsules and conventional tablets are swallowed. The vitamin B12 they contain is then absorbed through the digestive tract.

Because only part of a higher dose is actually absorbed, vitamin B12 supplements often contain relatively high amounts.

Orally disintegrating tablets and lozenges

Orally disintegrating tablets and lozenges dissolve in the mouth and can be convenient if you find swallowing difficult.

Some are also marketed as sublingual supplements, which are taken under the tongue.

Liposomal vitamin B12

In liposomal vitamin B12, the vitamin is enclosed in very small fat-like particles. This technology is intended to support absorption.

However, there are currently not enough clinical studies to conclude that liposomal vitamin B12 is absorbed better than other forms.

How to read the label

When choosing a vitamin B12 supplement, you can check the following information:

• The amount of vitamin B12 per daily dose
• The form of vitamin B12 used
• Whether folic acid or folate has been added
• The number of tablets or capsules per daily dose
• Any additional ingredients, sugar or sweeteners
• The material used to make the capsule

The last point may be particularly important if you follow a vegan diet. Some capsules contain gelatine, while others are made from plant-based capsule materials.

Read more about this in our article How to read a food supplement label.

Safety and important considerations

No tolerable upper intake level has been established for vitamin B12. However, this does not mean that taking unlimited high doses is necessary or advisable.

Are you taking medication, pregnant, breastfeeding or living with a medical condition? If in doubt, consult your doctor or pharmacist.

If you experience neurological symptoms or suspect a severe vitamin B12 deficiency, always consult your GP first.

Personal advice

Do you have questions about vitamin B12 or are you unsure which food supplement is most suitable for your personal situation? Our qualified health and supplement advisers and orthomolecular therapists will be happy to help. You can contact us by telephone, email or WhatsApp.