Fix Vitamin B12 Deficiency

We explain how a vitamin B12 deficiency can manifest itself, i.e. what symptoms it causes. Of course, you will also read how you can determine a vitamin B12 deficiency, what causes it can have and, of course, how you can remedy a vitamin B12 deficiency.

Vitamin B12 deficiency affects many people

Vitamin B12 deficiency affects many people. In Germany, 5 to 7 percent of the younger people and up to 30 percent of the older people are demonstrably undersupplied with vitamin B12. The number of unreported cases is likely to be much higher since vitamin deficiencies are not routinely checked during the usual medical check-up.

Symptomatic or asymptomatic vitamin B12 deficiency

A vitamin B12 deficiency can remain without symptoms for many years, which is due to the fact that the body’s reserves last for a very long time. Around 4000 micrograms of vitamin B12 are stored in the liver and muscles of an adult. These reserves are slowly used up when the vitamin is not supplied so that a deficiency can only become symptomatic after three or even more years.

When vitamin B12 levels are low but there are no symptoms yet, this is called an asymptomatic vitamin B12 deficiency.

Officially, symptomatic vitamin B12 deficiency includes pernicious anemia and also the so-called Hunter glossitis. On the other hand, unspecific symptoms are not always associated with a vitamin B12 deficiency by doctors.

The first non-specific symptoms of a deficiency

The first non-specific symptoms of vitamin B12 deficiency include the following. If you notice these, have your vitamin B12 levels checked:

  • numbness on the skin
  • Tingling in arms and/or legs
  • loss of appetite
  • burning tongue
  • cracked corners of the mouth
  • a noticeable weakness in performance and memory
  • frequent mood swings for no apparent reason
  • dizziness
  • difficulty concentrating
  • sleep disorders
  • Fatigue and exhaustion for no apparent reason

Later, there are serious illnesses, e.g. e.g.:

  • cardiovascular diseases
  • Hematological diseases (= diseases/disorders of blood formation), such as anemia, e.g. B. Pernicious anemia. Anemia is a lack of blood.
  • Dementia or dementia-like symptoms
  • Diseases of the nervous system: neuropathies (nerve diseases), e.g. B. funicular myelosis with unsteady gait and paralysis; attention deficit disorders; depression

Pernicious anemia as a result of vitamin B12 deficiency

In pernicious anemia, the red blood cells are enlarged. They also contain more hemoglobin (red blood pigment) than normal blood cells. These enlarged blood cells are also called megaloblasts, while normal blood cells are called normoblasts. Pernicious anemia is therefore one of the megaloblastic anemias, which also includes folic acid deficiency anemia.

The symptoms of megaloblastic anemia are similar to those of other anemias and consist of tiredness, rapid exhaustion, reduced performance, tachycardia, paleness, and possibly Hunter glossitis. Hunter glossitis is a pathological change in the tongue with a burning tongue, smooth surface of the tongue, and the tongue that is initially pale and later turns a fiery red tongue. In extreme cases, pernicious anemia can develop into funicular myelosis.

Funicular myelitis as a result of vitamin B12 deficiency

Funicular myelitis is a disease that is similar to multiple sclerosis but, unlike it, can be treated with the administration of vitamin B12. Funicular myelosis also causes degeneration of the myelin sheaths of the nerves in the brain and spinal cord. (Myelin sheaths are a kind of protective layer that surrounds nerve fibers). In most cases, abnormal sensations such as tingling or pain occur first, followed later by unsteady gait, muscle weakness, and (spastic) paralysis. If the brain is affected, cognitive disorders, fatigue, and psychoses appear.

Improvement comes so quickly

It is often asked how quickly the vitamin B12 deficiency symptoms improve when you start taking vitamin B12 as a dietary supplement. If you take vitamin B12 for vitamin B12 deficiency symptoms, the hematological symptoms usually improve within a week, the neurological symptoms within three months – depending on the severity, of course.

The daily requirement

While you usually take high doses of vitamin B12 in the event of a deficiency in order to remedy the deficiency quickly, the body only needs a small amount of vitamin B12 every day once it has filled its stores. The daily requirement of vitamin B12 is as follows (each in µg (micrograms) per day):


  • 0 to under 4 months: 0.5
  • 4 to under 12 months: 1.4


  • 1 to under 4 years: 1.5
  • 4 to under 7 years: 2.0
  • 7 to under 10 years: 2.5
  • 10 to under 13 years: 3.5
  • 13 to under 15 years: 4.0

teenagers and adults

  • 15 to under 19 years: 4.0
  • 19 to under 25 years: 4.0
  • 25 to under 51 years: 4.0
  • 51 to under 65 years: 4.0
  • 65 years and older: 4.0
  • Pregnant: 4.5
  • Breastfeeding: 5.5

Fix vitamin B12 deficiency

A vitamin B12 deficiency can easily be diagnosed by a doctor, an alternative practitioner, or a home test. If you have a vitamin B12 deficiency, you can generally correct it very easily.

The causes of vitamin B12 deficiency

Since vitamin B12, in contrast to all the other vitamins of the B complex, is found almost exclusively in animal foods, vegans are considered predestined for a vitamin B12 deficiency. But non-vegans can also suffer from a vitamin B12 deficiency.

Because of some medications, an unhealthy diet, or infections can lead to damage to the stomach and intestines, which then again makes a vitamin B12 deficiency very likely. Alcohol abuse, anorexia, and general forms of malnutrition (e.g. in old age, when eating too little or one-sidedly) are also considered causes of vitamin B12 deficiency.

Both vegans and non-vegans can be affected by a vitamin B12 deficiency – only the cause is usually different.

Omnivores with B12 deficiency usually have a gastrointestinal disease, while vegans simply lack the raw material because a purely plant-based diet contains little vitamin B12, if any, and does not always refer to taking a vitamin B12 supplement is thought.

How gastrointestinal complaints can lead to vitamin B12 deficiency

Vitamin B12 requires a healthy gastrointestinal tract to be fully absorbed for the following reason:

The so-called intrinsic factor is produced in the parietal cells of the gastric mucosa – a transporter protein to which vitamin B12 from food can attach itself so that it can then be absorbed in the small intestine (ileum).

However, when the mucous membrane of the stomach is damaged, there is first an intrinsic factor deficiency and consequently also a B12 deficiency. But a lot of people have a bad stomach, more omnivores than vegans.

The same is true for intestinal diseases. These, too, often lead to a vitamin B12 deficiency if the vitamin can no longer be fully absorbed, e.g. B. in an irritable bowel with frequent diarrhea or in chronic inflammatory bowel diseases, or of course if parts of the intestine have already been surgically removed.

How heartburn can lead to vitamin B12 deficiency

In the case of stomach problems, it does not even have to be a serious stomach disease, such as e.g. B. gastritis type A (inflammation of the stomach lining), which can also lead to a vitamin B12 deficiency. Heartburn is enough. Because many people take acid blockers (proton pump inhibitors, such as omeprazole) because of heartburn – and it is precisely these drugs that promote the development of B12 deficiency.

Omeprazole and similar acid blockers not only inhibit the formation of gastric acid, but also the formation of the intrinsic factor so that no more (or too little) vitamin B12 can be absorbed (malabsorption).

How parasites can lead to vitamin B12 deficiency

Infection with a fish tapeworm can also lead to a vitamin B12 deficiency. Fish tapeworm is most commonly infected by eating raw fish. The parasite sheds thousands of eggs daily, which are easily detected in stool, making diagnosis easy.

A vitamin B12 deficiency is therefore by no means a problem that would only affect vegan people. It’s a vitamin deficiency that can basically affect anyone, just like vitamin D deficiency, magnesium deficiency, or any other deficiency.

Determination of total vitamin B12 in serum

Many doctors still determine the total vitamin B12 level in the blood serum, but this does not make sense, since the inactive B12 is then also measured, which the body cannot use anyway.

It is, therefore, possible that this B12 total value is still perfectly fine, but in reality, there is already a vitamin B12 deficiency. Only when the B12 level has already fallen very dramatically would one be able to determine it from the total B12 value in the blood.

Methylmalonic acid determination in urine (MMA test)

The simplest method is the vitamin B12 urine test, which you can order online and carry out yourself at home. This test measures the level of methylmalonic acid in the urine, which is increased in vitamin B12 deficiency (both in the urine and in the blood).

However, since there are also people (especially those over 70 years of age) who have elevated methylmalonic acid levels without having a B12 deficiency and also (at any age) an intestinal flora disorder can falsify the methylmalonic acid levels, another test should be carried out to be on the safe side perform (if the methylmalonic acid test was elevated). This test measures the so-called holo-transcobalamin value (holo-TC) in the blood.

Transcobalamin is the transporter protein for vitamin B12 (cobalamin). When the active vitamin B12 binds to transcobalamin, this compound is called holo-transcobalamin

Blood holo TC test

With the Holo-TC test, only the active vitamin B12 is measured, so that a B12 deficiency can be detected at the very beginning and not only when the body’s vitamin B12 stores have already been more or less emptied. Of course, you can also just have the holo-TC value determined.

The methylmalonic acid test is then not additionally necessary. It is particularly useful for those who do not like having blood taken and is also available as a home test.

Homocysteine ​​determination in the blood

In addition, the homocysteine ​​level in the blood can be determined to be on the safe side. If it is elevated, a vitamin B12 deficiency – but also a folic acid deficiency and/or vitamin B6 deficiency – could be at play (or all three deficiencies together).

The reference values ​​for vitamin B12

Below are the reference values ​​for vitamin B12 (for adults) so that you can correctly classify your readings.

Reference values ​​for vitamin B12 in serum

If your doctor measures the vitamin B12 in the serum and it is too low, there is clearly a vitamin B12 deficiency. However, if it is normal but on the lower end of the normal scale (low-normal), you should have other tests are done, such as the holo-TC score or the MMA test. Because the serum vitamin B12 level can still be normal when there is actually already a vitamin B12 deficiency, the serum measurement is not suitable for diagnosing an incipient deficiency:

  • Normal: 300 – 900 pg/mL (220 – 665 pmol/L)
    possible deficiency: 200 – 300 pg/ml (150 – 220 pmol/l)
  • Deficiency: below 200 pg/mL (150 pmol/L)
    severe deficiency: below 150 pg/ml (110 pmol/l)

Reference values ​​for methylmalonic acid MMA in urine and blood

The reference values ​​for the determination of methylmalonic acid in urine are as follows:

  • B12 deficiency unlikely: values ​​below 1.5 mg MMA per g creatinine
  • B12 deficiency probable: values ​​between 1.5 and 2.5 mg MMA per g creatinine
  • B12 deficiency: levels higher than 2.5 mg MMA per g creatinine

The reference values ​​for the determination of methylmalonic acid in blood serum are as follows:

  • B12 deficiency unlikely: values ​​between 9 and 32 µ/l (equivalent to values ​​between 76 and 280 nmol/l)
  • B12 deficiency probable: values ​​of more than 32 µg/l (corresponds to about 280 nmol/l)

If there is a low holotranscobalamin level at the same time, a manifest vitamin B12 deficiency can be assumed with certainty.

Reference values ​​for holotranscobolamine in serum

The reference values ​​for the determination of holotranscobalamin in serum are as follows:

  • B12 deficiency unlikely: at values ​​above 70 pmol/l
  • B12 deficiency possible/borderline result: 35 – 70 pmol/l
  • B12 deficiency probable: at values ​​below 35 pmol/l

Since low holo-TC levels are also present in the case of renal insufficiency, kidney values ​​should always be checked, especially in older people.

Different units: how to convert

If your serum vitamin B12 level was determined but your result was given in a different unit, you can convert it as follows and then compare it back to the reference values ​​above:

  • pmol/L x 1.355 = pg/mL = ng/L
  • ng/L x 1 = pg/mL

Please note, however, that reference values ​​can often differ depending on the type of analysis and laboratory so you should use the reference values ​​of the respective laboratory as a precaution.

This is how vitamin B12 is absorbed by the body

Vitamin B12 can be absorbed by the body via two mechanisms:

  • No more than 1.5 micrograms of vitamin B12 can be ingested per meal via active absorption by means of transporter proteins (intrinsic factor).
  • 1 percent of the vitamin B12 consumed can be absorbed (without transporter proteins) via passive absorption by diffusion, which is particularly interesting when taking high-dose food supplements. Because if a high-dose vitamin B12 preparation provides a daily dose of 1000 micrograms of vitamin B12, for example, you can still absorb 10 micrograms of vitamin B12 via passive diffusion, which can cover the requirement well.

This is how you can correct a vitamin B12 deficiency

If it is now clear that there is a vitamin B12 deficiency, then the question naturally arises as to how this can be remedied. The necessary measures depend on the cause of the defect.

Eliminate vitamin B12 deficiency in chronic gastrointestinal complaints
If you suffer from chronic gastrointestinal complaints, optimizing your gastrointestinal health should be the focus of further action. At the same time, a high-dose vitamin B12 preparation (daily dose of 1000 micrograms) makes sense, since this can be absorbed by passive diffusion, so it can often remedy the previous undersupply even with an ailing gastrointestinal tract.

In some cases, vitamin B12 injections are an even better solution, especially when there is already a pronounced vitamin B12 deficiency. They are given intramuscularly, i.e. into the muscle, and can usually remedy a vitamin B12 deficiency within a few weeks.

Eliminate vitamin B12 deficiency when taking medication

If you’re taking medications that may contribute to vitamin B12 deficiency, talk to your doctor about whether they’re still needed or whether you can stop taking them. If you have to continue taking your medication, ask your doctor whether it is sufficient if you regularly take a vitamin B12 supplement or – if the deficiency is severe – whether you should not have a B12 injection regimen first otherwise your vitamin B12 deficiency may not be corrected or may only be corrected slowly.

Dietary conditions correct vitamin B12 deficiency

If the vitamin B12 deficiency has developed as a result of a vegan diet or other unknown causes, you can remedy the deficiency by regularly taking a vitamin B12 supplement. A wide variety of preparations are available for this purpose.

Correct vitamin B12 deficiency with these preparations

If you want to remedy a pronounced vitamin B12 deficiency, high-dose vitamin B12 preparations with a daily dose of 1000 micrograms of vitamin B12 are recommended.

Capsules with vitamin B12

Capsule preparations that contain a mixture of the best forms of vitamin B12, i.e. the storage vitamin B12 (hydroxocobalamin) and the active B12 forms (methylcobalamin and adenosylcobalamin), are ideal.

Nose drops with vitamin B12

Vitamin B12 nasal drops are now also commercially available. With drops of effective nature, for example, you can take 1000 micrograms of vitamin B12 per daily dose (2 drops). The vitamin can be absorbed through the nasal mucosa, bypassing the gastrointestinal tract.

Toothpaste with vitamin B12

Toothpaste with vitamin B12 can also help to cover the daily requirement of vitamin B12. They must be used at least twice a day to affect vitamin B12 levels.

In a 2017 study, vegans who used an appropriate toothpaste for 12 weeks had significant increases in both holo-TC and serum B12, the latter increasing by an average of 81 pg/mL, which is quite a lot. If the values ​​are below 150 to 200 pg/ml, there is a deficiency. Levels of 300 pg/ml and above are considered normal, so regular use of enriched toothpaste can continuously improve or maintain healthy levels of B12.

Injections usually remedy vitamin B12 deficiency quickly

Intramuscular vitamin B12 injections (e.g. from Medivitan) can also be used in the case of a diet-related vitamin B12 deficiency – if the value is already very low. These are usually given once or twice a week for a few weeks. Because the oral intake of vitamin B12 preparations or the use of an enriched toothpaste alone is often not enough to remedy the vitamin B12 deficiency as quickly as possible and to improve the symptoms.

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Written by Crystal Nelson

I am a professional chef by trade and a writer at night! I have a bachelors degree in Baking and Pastry Arts and have completed many freelance writing classes as well. I specialized in recipe writing and development as well as recipe and restaurant blogging.

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