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Vitamin B12 - fact sheet, daily requirement and more

Vitamin B12 - profile, daily requirement & more

You want to know more about vitamin B12? Then this is the right article for you. I will explain the most important details about B12. We start with a fact sheet about vitamin B12 and then we continue with intake, daily requirement, importance, overdose, deficiency, test variants and ways to meet the daily requirement. In addition, you will find special information for vegans and vegetarians and what forms of supplements can be useful.

Here is in advance a short Overview for you:

  1. Profile
  2. Recording
  3. Daily requirement
  4. Meaning
  5. Overdose
  6. Deficiency
  7. Test
  8. Foods
  9. Vegan
  10. Food supplement

Notice: This article is not a substitute for medical advice, but only provides general information about vitamin B12. Please consult your doctor if you feel unwell or want to prevent health problems with medical care.

Vitamin B12 REACTION LETTER at a glance

Assignment: Group of water-soluble vitamins belonging to the cobalamins
Synonyms: Coenzyme B12, adenosylcobalamin,
Important for: Amino acid and lipid metabolism, hematopoiesis, homocysteine and folic acid metabolism.
Daily requirement: 4 micrograms from the age of 13₁.
Recording: through food intake or dietary supplements
Overdose: overprovision is not possible
Deficiency symptoms: e.g. fatigue, susceptibility to infections, mood swings and even dementia and depression
Food: Meat and dairy products, foods supplemented with B12
Nutritional supplement: As drops, pellets, capsules, toothpaste or lozenges

How can you absorb vitamin B12?

Vitamin B12 intake

Vitamin B12 is a particularly well-known vitamin, as it is repeatedly discussed in relation to vegan and vegetarian nutrition. In itself, B12 is produced by microorganisms such as bacteria. The vitamin can be produced on the one hand by a Diet with animal products ingested and on the other hand many vegans or vegetarians successfully use Food supplements to cover their daily requirements.

In fact, we humans have bacteria in the large intestine that produce vitamin B12. However, the vitamin is absorbed beforehand in the small intestine, so the bacteria are too far "back" for the body to process the bacteria's B12.

What is the daily requirement of vitamin B12?

In principle, the daily requirement of vitamin B12 can be covered by a diet containing animal products. However, the amount of B12 in animal foods is relatively difficult to measure, and B12 deficiency is also found more and more often in mixed-food people. Therefore, especially vegans, vegetarians and seniors are recommended to supplement vitamin B12.

According to the DGE, the daily requirement is 4 µg for adolescents and adults. A daily dose of 0.4 µg is recommended for infants aged 0 to 4 months. From 4 months, the requirement increases to 1.4 µg and rises to 4 µg by the age of 13.₂

What is the importance and function of vitamin B12 in the body?

For our health and metabolism, vitamin B12 has an essential importance. It supports the metabolism of amino acids and lipids as well as the energy, homocysteine and folic acid metabolism, the Blood formation and the Synthesis of messenger substances in the nervous system in the body.₃

The functions of vitamin B12 at a glance:

  • Promotes amino acid and lipid metabolism
  • Supports blood formation
  • Optimizes energy, homocysteine and folic acid metabolism
  • Supports the formation of messenger substances in the nervous system

Is B12 overdose possible?

Even with a high dosage of food supplements, an overdose with vitamin B12 is hardly possible, since the body excretes excesses of the water-soluble vitamin through the urine.₄,₅

Again and again we hear about the myth that a regular high dosage of B12 supplements could cause cancer. However, it is exactly the other way around: for reasons that are as yet unknown, various types of cancer can result in disproportionately high B12 serum levels. However, the high B12 level is not the cause of the cancer, but the cancer is the cause of the elevated B12 level.₆

When does a deficiency occur?

A deficiency of the important vitamin can affect not only vegans and vegetarians. Particularly in older people, the absorption of vitamin B12 deteriorates via the IntestineIt is therefore important to check the budget regularly and, if necessary, to supplement it with food supplements. Many Medication also lower the absorption of B12, so regular checks are recommended if you regularly take medication.₅

Deficiency more common in: Vegans, vegetarians, seniors, people who regularly take medication.

What tests can determine the B12 level?

There are three particularly well-suited tests that can be used to check B12 balance: Serum B12, Holo-Transcobalamin II and Methylmalonic acid.

The simplest test is the serum value or total vitamin B12. However, this is the most inaccurate, so that it can only be assumed that the body is supplied with sufficient B12 if the serum value is more than 400 ng/l. If the serum value is between 200 and 400 ng/l, the holo-transcobalamin II value should be determined.

The value of Holo-Transcobalamin II, Holo-TC for short, is somewhat more accurate than the serum value. If the Holo-TC value is above 50 pmol/l, you are probably sufficiently supplied with B12. If your value is lower, you probably have a B12 deficiency and should start supplementing vitamin B12 or if you are already supplementing increase the dose or change the supplement. You should also have your methylmalonic acid level checked to see if you are actually deficient.

With the methylmalonic acid (MMA) value, you can check whether there is actually a deficiency if the holo-TC value is unclear. If your MMA value is higher than 271 nmol/l, your B12 balance is probably in the green zone.

The right test: Since the MMA test is relatively expensive and the serum B12 value is rather inaccurate, I usually recommend testing the Holo-TC value. However, if you want it to be particularly accurate, the MMA test is the right one for you.

What foods contain B12?

Since the absorption in the intestine, as well as the B12 content of food varies, I tend to recommend covering the B12 requirement via dietary supplements. For ethical, ecological and health reasons, I generally recommend a vegan diet, but I would still like to educate as comprehensively as possible about the vitamin and therefore list here some animal foods that contain B12:

  • Offal of lamb and beef (50-90 μg per 100 gram)
  • Chicken liver (25 μg per 100 gram)
  • Eggs (1-2 μg per 100 gram)
  • Milk (0.4 μg per 100 grams)

What do vegans and vegetarians have to consider regarding vitamin B12?


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The DGE considers vitamin B12 a critical nutrient for vegans and vegetarians because B12 is hardly found in plant foods. Therefore, the DGE recommends regular dietary supplementation, as well as a check of the B12 level.

The body stores B12 mainly in the liver and muscles. This store can supply the body for several years, if the store was previously sufficiently filled. So you definitely don't have to worry about your B12 balance right away when you start eating a vegan or vegetarian diet. However, you should not wait too long and take a closer look at your B12 storage to see how well your storage is filled. You can find out more about the various tests further down in this article.₇

Find the right supplement with vitamin B12

When it comes to vitamin B12, there are countless supplements in various forms such as lozenges, drops or toothpaste. However, the form of the supplement is far less important than the correct dosage.

However, it can also be useful to pay attention to the form of the vitamin contained, as B12 can be supplemented as cyanocobalamin, methylcobalamin, adenosylcobalamin and hydroxocobalamin. Many supplements also contain a combination of different forms to ensure that the B12 can be absorbed.

A small percentage of humanity cannot metabolize cyanocobalamin properly. If you are diagnosed with this or are already taking a supplement with cyanocobalamin and your B12 levels still do not increase, you should switch to a supplement with methylcobalamin, adenosylcobalamin, or hydroxocobalamin (or a combination thereof).

When you Vitamin B12 preparations you would like to take, you should Coordinate nutritional supplementation with your primary care physicianin order to avoid overdosing. If a supplement is useful, then the following preparations in drop, tablet or capsule form are recommended.

Ensure vitamin B12 supply

Whether you eat a vegan, vegetarian, or mixed-food diet, it's good to check your B12 levels regularly and use a supplement if necessary. If you eat a balanced and eat a wholefood dietexercise and go outdoors, you can already help many people through your healthy lifestyle. nutritional diseases and prevent deficiency symptoms. In the case of vitamin B12, however, you should go beyond this and carry out blood tests with your family doctor from time to time in order to detect a potential deficiency at an early stage. In this case, a dietary supplement is then recommended.

Do you have any questions or suggestions about this post on vitamin B12? Then feel free to write me a comment.

All the best,

Julian from CareElite

PS.: You want to know, why we live vegan? Check out the linked article to learn our reasons! And if you want to learn more about other nutrients, then feel free to take a look next at the post about Vitamin D.

₁,₂ Deutsche Gesellschaft für Ernährung e. V.: Vitamin B12 (Cobalamine), [15.05.2021].

₃ Zentrum der Gesundheit: Vitamin B12: Tasks and functions, [15.05.2021].

₄ M. F. Sokoloff, E. H. Sanneman, M. F. Beard: Urinary Excretion of Vitamin B12. [15.05.2021].

₅ German Nutrition Society: Selected questions and answers on vitamin B12, [15.05.2021].

₆ Y. Wakatsuki, M. Inada, H. Kudo, G. Oshio, T. Masuda, T. Miyake et al.: Immunological characterization and clinical implication of cobalamin binding protein in human gastric cancer, [15.05.2021].

₇ C. Felchner: Vitamin B12, [15.05.2021].

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Julian Hölzer

Julian Hölzer

Hi, my name is Julian and I am a trained vegan nutritionist. In 2016 I started to get involved with veganism and quickly learned how big an impact our diet has on the environment and how diverse plant-based diets can be. That's why I want to inspire you to get involved with veganism too.

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