The allrounder amongst B-vitamins

What you should know about Vitamin B12Do you remember your mother telling you as a child that you were not allowed to leave the table until you finished the meat on your plate in order to grow “strong and tall”? Apart from proteins and minerals, meat contains the important vitamin B12. Vitamin B12 is one of the most important nutrients for a healthy body. In human biology, it is especially appreciated due to its contribution to the protection of the nerves and the blood formation. Vitamin B12 is thus participating in various processes as an all-rounder talent. It plays a major role in growth and should therefore be a loyal companion through childhood. Moreover, vitamin B12 not only provides you with energy to master your daily routines but also protects your heart from inflammations and supports your thinking skills! With regard to its role as an allrounder, it is even more important that you ensure sufficient supply of vitamin B12 in order to avoid deficiency. 

In this article, you can read why vitamin B12 is that important for you, why you should check your vitamin B12-level regularly and how you can avoid resp. remedy deficiency!





What is vitamin B12?

Like the other B-vitamins, vitamin B12 belongs to the water-soluble vitamins. In contrast to the other B-vitamins, vitamin B12 is stored in the liver. As the body cannot produce the vitamin, it must be taken up through food. Thus, it belongs to the essential vitamins. [1] Only microorganisms such as bacteria are able to produce it independently. [2]

At the center of its chemical structure, vitamin B12 contains cobalt, which belongs to the group of heavy metals. For this reason, vitamin B12 is also called cobalamin. The term cobalamin comprises the forms in which vitamin B12 exists. This includes amongst others: cyanocobalamin, hydroxycobalamin, methylcobalamin and adenosylcobalamin. In the body, these forms are transformed into the biochemically active form of vitamin B12 methylcobalamin and 5-adenosylcobalamin.[3]

The biochemically active form of a nutrient can directly be used by the body and can thus take immediate effect. [2]

The characteristics of a vitamin are determined by its chemical structure. Vitamin B12 is very air- and light-sensitive. The average loss through preparation (by e.g. cooking) of foods that contain vitamin B12 is approx. 12 %. [1]

What is a B-vitamin?

B-vitamins are the precursor to coenzymes and make an important contribution to the energy metabolism. Coenzymes are catalysts and start up all metabolic processes. Another characteristic of B-vitamins is that they belong to the water-soluble vitamins. Therefore, they constantly have to be taken up through food as the body cannot store them - apart from vitamin B12. Water-soluble means that the vitamins can be excreted via the kidneys. [4]

The body’s own production of vitamin B12 - a myth?

Whether vitamin B12 can be produced by the body or not is not clear yet. Often, the human vitamin B12-production is compared of that of cows, which produce their own vitamin B 12. The bacteria in the digestive tract of the ruminants produce vitamin B12 from cobalt from food. Cobalt serves as central atom in the chemical structure of vitamin B12. [5]  The human gut flora is also able to produce vitamin B12, however, in the wrong area. The production takes place in the large intestine, where the bacteria for this process can also be found. The absorption of vitamin B12, however, takes place in the small intestine. Hence, the vitamin cannot enter the blood and be stored in the liver. Instead, it is excreted in the stool. The study situation is controversial whether the body’s own vitamin B12 production might eventually contribute to its vitamin B12 supply. [6]

Which effects does vitamin B12 have in the body?

Vitamin B12 plays a major role in various metabolic processes. Amongst others, it is essential for the metabolism of folic acid. Furthermore, vitamin B12 is contributing to blood formation and to the degradation of fatty acids. [1]

Further central metabolic processes to which vitamin B12 is contributing: [1]

  • DNA-formation
  • nerve protection and regeneration
  • cell division and cell respiration
  • blood formation
  • synthesis of neurotransmitters
  • detoxification

    Vitamin B12 and folic acid metabolism

    Folic acid and vitamin B12 belong to the group of B-vitamins. Old designations used for folic acid were vitamin B9 and B11. Vitamin B12 deficiency induces folate deficiency as folic acid can no longer be transformed into the active form. The functions of folic acid cannot be fulfilled. In turn, folic acid excess induces vitamin B12 deficiency. In both cases, health consequences may be expected. [1, 2, 7, 8]

    Extra knowledge for experts

    In the body, folic acid is transformed into tetrahydrofolate (THF). Its main functions are DNA formation, cell division and gene expression. Folic acid is of major importance for the synthesis of methionine from homocysteine. Homocysteine is an amino acid which in large quantities encourages cardiovascular diseases. The most frequent consequence is arterial calcification (arteriosclerosis). Especially older people, overweight people and smokers show higher homocysteine levels. In this metabolism, vitamin B12 also is an important factor. It supports folic acid in methionine formation by transforming folic acid into its active form THF. An increased homocysteine-level can either be lowered by the intake of B-vitamins or by physical activity.

    What is methionine?

    Methionine is an essential amino acid and is needed for the formation of protein. It contributes to the production of certain fats, nerves and the DNA.

    What is a coenzyme?

    A coenzyme is a vitamin which like enzymes acts as a catalyst. Catalysts lower the energies needed for metabolic processes.

    Vitamin B12 and blood formation

    Vitamin B12 is an important element for blood formation. It promotes the maturing process of the red blood cells, the erythrocytes, in the bone marrow. This is due to the fact that it is participating in DNA-formation and cell division. This stimulates the production of the red blood cells. As a consequence, anaemia (pernicious anemia) is one symptom in case of vitamin B12 deficiency. [1, 2, 7]

    Vitamin B12 and nerve cells

    Vitamin B12 is often referred to as the nerve vitamin. It is responsible for the production of the myelin sheath which surrounds the nerve cells as a membrane. Myelin is a substance which consists mainly of fats. Myelin protects the nerve cells and also supports the stimulus transmission. In case of vitamin B12-deficiency (Link einfügen) this protection is no longer guaranteed so that the nerve cells could be damaged. This may result in paralyses or diseases such as multiple sclerosis. [9]

    How much vitamin B12 do I need per day?

    The German Nutrition Society (DGE) recommends a daily intake of vitamin B12 for teenagers (older than 15 years) and adults of 3.0 µg daily. Children need, depending on their age, 1.0 - 2.0 µg daily. Pregnant and breastfeeding women have an increased need of 3.0 µg for pregnant women and 4.0 µg daily for breastfeeding women. [10]

    The National Institutes of Health recommends values that approximate to those of the DGE. Teenagers (older than 13 years) and adults should take in 2.4 µg vitamin B12 daily. Pregnant women, however, should reach an intake of 2.6 µg and breastfeeding women 2,8 µg daily. [11]

    How is vitamin B12 absorbed by the body? A biochemical explanation

    In foods, vitamin B12 is bound to dietary proteins. Once arrived in the stomach, it is released by the stomach acid and bound to the R-protein. The parietal cells of the stomach secrete the protein intrinsic factor (IF) which is essential for the absorption of vitamin B12. The vitamin B12 R-protein complex and IF are transported to the small intestine. The digestive enzyme trypsin from the pancreas dissolves the vitamin B12 from the vitamin B12 complex so that B12 can bind to the IF. After absorption via the mucous membrane of the small intestine the vitamin B12 passes into the blood. By means of carrier proteins, also called transcobalamins, the vitamin B12 is transported to all cells and to the liver. 30 % of the vitamin B12 in the blood is bound to transcobalamin. Only one to three percent of the vitamin B12 contained in food are absorbed. Therefore, you should always use high-dosage preparations in case of a deficiency. On the basis of the the vitamin B12 absorption you can understand to what extent this process depends on the existence of certain proteins. The decreased incidence and the lack of these proteins causes amongst others vitamin B12 deficiency. [1, 12, 13]

    Good to know: In the liver, vitamin B12 can be stored for nearly three years. Approximately two to five micrograms of vitamin B12 are stored in the body, half of which in the liver. Nearly 0.1 % get lost due to emission to the intestine. Vitamin B12 is excreted via the bile and is, however, resumed by the liver. This is termed the enterohepatic circulation. It means that vitamin B12 is again taken up, secreted and resumed by the liver. [1, 12]

    What helps vitamin B12 absorption?

    • normal stomach function for the production of the intrinsic factor
    • normal pancreatic function for the production of trypsin
    • normal bowel function for absorption of vitamin B12

    The intrinsic factor is a protein which enables the absorption of vitamin B12 in the small intestine. An inflammation of the gastric mucosa, a gastritis, inhibits the production of the intrinsic factor which may result in vitamin B12 deficiency. [2]

    As the membrane of the small intestine represents the last hurdle before vitamin B12 enters the blood, this membrane needs to be intact. Damages to the membrane of the small intestine affect the uptake into the blood so that vitamin B12 gets excreted. [1, 2, 12]

    Trypsin is a digestive enzyme which is produced by the pancreas and above all needed for the protein digestion. As vitamin B12 is initially bound to the R-protein, this complex needs to be dissolved by trypsin. After the dissolution, it is freely available in the small intestine and is bound to the intrinsic factor. A pancreatitis, which is an inflammation of the pancreas, can encourage trypsin deficiency. [14]

    Food sources of vitamin B12

    Vitamin B12 can mainly be taken up through foods of animal origin like meat, fish, eggs and milk. If seaweed is suitable as a vegetable alternative for vegans and vegetarians could not finally been clarified in recent studies. Up to now, only in the nori seaweed one form was found which might possibly be usable for the human organism. Results from so-called in vitro studies (in a test tube) are promising. Apart from supplements, vitamin B12 can also be taken up through vitamin B12-enriched foods like e.g. juices. [15]

    vegetarian and vegan alternatives for vitamin b1210 foods rich in vitamin b12
    Good to know: A dietary overdosage is nearly impossible as natural vitamin B12-levels in foods are not as high as in vitamin B12-supplements and excess vitamin B12 is excreted via the kidneys. Only a long-term, high-dosage intake can lead to an overdosage in the body which can strain the kidneys. When preparing food, you should consider that vitamin B12 is very heat- and light-sensitive. When heated, meat and milk lose a lot of their vitamin B12.

    Vitamin B12 - deficiency

    According to the National Food Consumption Study II, men in contrast to women more easily cover their daily requirement of vitamin B12. One possible reason could be their different diet. The American Society for Microbiology could show that men more often eat foods of animal origin than women. A pure vegetable diet contributes to the occurence of vitamin B12 deficiency. Hence, people eating a vegan diet have a high risk of not taking up enough vitamin B12 through food. Meanwhile, according to statistics, one million Germans are eating vegan. [16, 17]

    median of uptake vitamin b12

    A vitamin B12-deficiency is not only influenced by the different eating habits of men and women and other gender differences. Age is another important factor. Nearly one fourth of Germans over 65 years show a vitamin B12-deficiency. Especially with increasing age, vitamin B12-deficiency is not uncommon as less stomach acid is produced. For this reason, older people should pay attention to adequate intake of vitamin B12. [18, 19]

    Due to the storage capacities of the liver and the muscles, insufficient supply of vitamin B12 is not immediately noticeable through symptoms. Only when the stores are exhausted, first symptoms occur. The stores of the liver last for up to three years. Vitamin B12 is contributing to various central metabolic processes and thus symptoms occur where these processes take place. [1, 2, 7]

    Vitamin B12-deficiency - Symptoms

    The symptoms of vitamin B12-deficiency are manifold and often unspecific which complicates the detection of a deficiency. As a coenzyme, vitamin B12 is involved in numerous metabolic processes and thereby supplies the body with energy. In case of a vitamin B12-deficiency, the performance is heavily affected.

    In general, the following symptoms may occur: [20]

    • fatigue
    • exhaustion
    • headaches
    • concentration disorders
    • digestion problems
    • depressions

    Biochemical effects

    In case of vitamin B12-deficiency, folic acid is not reactivated which leads to a functional deficiency of folic acid in the body. A folic acid-deficiency in turn reduces the rate of DNA-replication and cell division. This deficiency can cause further deficiency symptoms and the transformation of homocysteine (Link einfügen) into methionine can no longer take place. [2, 8, 21, 22]


    In case of cobalamin deficiency, the cell division rate in the bone marrow decreases which leads to the so-called pernicious anaemia, a special form of anaemia. The bone marrow is the tissue where red blood cells are produced. Without vitamin B12, the blood cells cannot be formed properly. As the blood cells transport oxygen. Due to this, a lack of blood cells induces a lack of oxygen and decreased nutrient uptake of the cells. This leads to general deficiency symptoms in the organism such as weak performance, low immunity, fatigue, concentration disorders and exhaustion. [1, 20]

    Nervous disturbances

    Cobalamin is of particular importance for the protection of the nerve cells. Vitamin B12-deficiency leads to a reduced production of nerve fibres in the bone marrow. As the symptoms are very similar to numerous neurological diseases such as e.g. slipped discs, vitamin B12-deficiency often is diagnosed rather late.

    The symptoms in the neurological field may be: [20]

    • nervousness and irritability
    • numbness or “formication” of the limbs
    • severe limb pain
    • painful limb misperceptions (hands / arms, feet / legs)
    • fatigue
    • depressions

    Good to know:

    Vitamin B12-deficiency can lead to funicular myelosis. This disease is a damage of the spinal cord which may favor disturbances of the nervous system and may lead to paraplegia. [23]

    Digestion problems

    Vitamin B12 plays a special role with regard to the absorption and metabolization of various nutrients. A deficiency may be apparent in the form of symptoms such as lack of appetite, diarrhea, constipation and inflammatory reactions in the oral, stomach and bowel area. [2]

    Further possible symptoms

    Diminished vision can also be a symptom of cobalamin-deficiency. As vitamin B12 is involved in messenger substances and hormones, a deficiency can lead to mental disorders like depressions through to psychoses. Due to the role of cobalamin in energy metabolism, this is impaired and leads to muscle weakness, fatigue, exhaustion and concentration disorders. [2]

    Vitamin B12-deficiency - Causes

    Vitamin B12-deficiency may have different causes which differ from malnutrition to disturbed absorption (malabsorption) in the gastrointestinal tract.

    Basically, the following causes can be defined:[1, 2, 14, 20, 24]

    • long-term malnutrition
    • stomach resection, lack of gastric acid, gastritis, lack of intrinsic factor
    • medications inhibiting gastric acid secretion
    • bad composition of gut flora
    • lack of transcobalamin
    • absence of trypsin due to diseases of the pancreas
    • exhaustion of liver stores
    • lack of folic acid

    You can see from the following table which medications can impair the absorption of vitamin B12:

    drugs then encourage vitamin b12 deficiency

    Risk groups

    Vitamin B12-deficiency with insufficient absorption can happen to everybody.

    The following risk groups are often affected by a deficiency:

    • Pregnant and breastfeeding women
    • Vegans and vegetarians
    • older people
    • people after stomach resection
    • people suffering from chronic pancreatitis or diabetes type 2
    • heavily stressed people

    Pregnant and breastfeeding women should supply both themselves and their children with vitamin B12. Therefore, they also have an increased demand. The vitamin B12-supply plays an important role for the physical and mental development of the unborn resp. newborn child. Vitamin B12-deficiency during pregnancy can, in the worst case, lead to a miscarriage. Therefore, a deficiency must be avoided by all means. [25]

    Causes Vitamin b12 deficiencyVitamin B12 can mainly be found in animal-based foods. Therefore, vegans are heavily affected by vitamin B12-deficiency as they cannot take it up through vegetarian foods. Vegetarians, in contrast, could resort to foods such as milk, eggs, curd depending on the form of vegetarian diet. However, the quantities are that small that also most of them are not spared. Recent studies deal with the topic whether seaweeds can help to cover the vitamin B12-requirement as they contain one form of vitamin B12. However, studies have shown that vitamin B12 in seaweed cannot be used by the human body. Shiitake mushrooms are said to be another good source and studies are dealing with the fact if the same problem arises as for seaweed. [26, 27]

    In older people, only little vitamin B12 is transported to the small intestine as they produce too little stomach acid as well as too little intrinsic factor. Therefore, too little vitamin B12 is absorbed in the stomach from food. [20]

    After surgical stomach resection, the supply of vitamin B12 from supplements must be guaranteed as the intrinsic factor cannot be produced without a stomach. [2]

    People suffering from pancreatitis, an inflammation of the pancreas, have a vitamin B12-deficiency. In pancreatitis, the digestive enzyme trypsin is produced in too small quantities. Trypsin is, however, an important factor for the release of B12 from food. If vitamin B12 cannot be released it cannot be used by the body. [14]

    People suffering from diabetes mellitus type 2 and who take metformin, are - according to studies - only be able to absorb small quantities of vitamin B12 as metformin inhibits vitamin B12-absorption. [28]

    In highly stressful times, vitamin B12-deficiency can also occur as the demand rises because of stress. [29]

    When you are constantly stressed, the stress hormone cortisol (Link einfügen) is produced in greater quantity. Apart from vitamin B12-deficiency, this may result in other health consequences.

    Vitamin B12-deficiency - Therapy

    How do I treat vitamin B12-deficiency?

    The therapy needs to be adjusted to the severity of the vitamin B12-deficiency. Treatment options range from a diet rich in vitamin B12 to the use of supplements and injections. As deficiency symptoms are rather unspecific, the vitamin B12-level should be measured (Link einfügen) in order to determine the most appropriate treatment option.

    Vitamin B12-supply through food

    As mentioned before, vitamin B12 can nearly exclusively be taken up through animal-based foods. Vegetarian foods such as vegetables, fruit, legumes, herbs, nuts, cereals, amaranth, quinoa, rice and vegetable oils/fats do not contain any vitamin B12. In order to supply enough cobalamin via nutrition, it makes sense to know the content of vitamin B12 of the individual foods. An overdosage by nutrition is nearly impossible as the natural cobalamin-content is not as high as in vitamin B12-supplements and the excess vitamin B12 absorbed is excreted by the kidneys. When preparing foods, please pay attention to the fact that vitamin B12 is very heat- and light-sensitive. This means that the vitamin can be destroyed by heat and the vitamin B12-content of the foods is reduced after frying or cooking. [2]

    Foods that are highest in vitamin B12

    As the food table shows, the daily requirement of non-vegetarians who are not pregnant or breastfeeding can easily be covered by 100 grams of tuna or 100 grams of lamb. Lacto-vegetarians who do not avoid milk and dairy products, can cover their daily requirements with two chicken eggs, 100 grams of cottage cheese or 100 grams of plain yoghurt. Vegans eating fish can cover their daily requirements for example with 100 grams salmon. [1]  

    Vitamin B12-injections

    Vitamin B12 can also be administered by injections into the muscle. These injections are very highly dosed and are given by a physician in case of a severe deficiency to replenish the vitamin B12-stores quickly. The doctor normally administers one injection per month. This therapy is suitable for people who cannot absorb vitamin B12 due to digestive absorption disorders. Via injection into the muscle, it is immediately available for the body and bypasses the stomach and small intestine. Attention should be paid to the fact that certain medications (Link einfügen) can affect the absorption of vitamin B12. Details should be clarified with your doctor. [20]

    According to the National Institutes of Health, apart from vitamin B12-injections high-dosage oral supplements are also suitable for therapy of vitamin B12-deficiency. According to a study, 1,000-2,000 mg vitamin B12 taken in daily are as good as injections for raising vitamin B12-blood levels. However, this varies from person to person. [30, 31]

    An overdosage by vitamin B12-injections, so far, seems to be impossible. Excess vitamin B12 is excreted via the kidneys as it is water-soluble. However, you should follow the consumption recommentations. [32]

    Vitamin B12 - supplements

    What makes a good supplement?

    • contains the active form
    • high bioavailability
    • hardly any or few additives
    • suitable for many consumer groups
    • beneficial ingredients
    • presentation in the form of capsules
    • tasteless

    A good vitamin B12-supplement should contain vitamin B12 in its active form. This means, that it doesn’t need to be transformed after absorption and can immediately be used by the body. The active forms of vitamin B12 are methylcobalamin and adenosylcobalamin. If you don’t use the active from of B12 and if you have a digestive absorption disorder, the vitamin B12 cannot work in the body. In case of a good absorption rate one speaks of a ‘high bioavailability’ as it is quickly made available to the body.

    The product should contain as little additives as possible so that vitamin B12 can unfold its full effect and is not affected in any way. The supplements should be suitable for many consumer groups so that it is possible for as many people as possible to optimize their vitamin B12-levels! This means that it should be vegan, vegetarian, gluten- and lactose-free. Otherwise, there should be alternatives for each of these consumer groups.

    In the best case, the supplement contains ingredients that are beneficial for the absorption in the body. In case of vitamin B12, the combination with other B-vitamins is favorable, as they are interacting. Vitamin B12 and folic acid are the best match. [2, 24]

    As tastes are different, a tasteless supplement is particularly attractive. The presentation in the form of capsules or droplets is easier to use than tablets.

    Is B12 toothpaste an effective supplement for vegans?

    According to recent studies, the daily vitamin B12-requirement can indeed be covered through teeth cleaning. The toothpaste is enriched with vitamin B12. It has been shown that the use of this agent raised the concentration of holotranscobalamin, the active form of vitamin B12, in the blood. Thus, B12-enriched toothpaste is an alternative for supplementation. One of the advantages is that the vitamin B12 is absorbed through the oral mucosa and enters the bloodstream. Therefore, this kind of preparation can be used by people who suffer from gastrointestinal disorders. [33, 34]


    In the meantime it is common knowledge that high doses of approx. 1,000 µg oral vitamin B12- supplementation - in spite of an absorption disorder - lead to sufficient coverage of demand. [30, 31]

    You can increase vitamin B12-levels by the following measures:

    • daily oral intake of 500 to 1,000 µg cobalamin until the symptoms have improved with renewed control of holotranscobalamin-levels

    • then, if necessary, intake of further 250 µg daily for long-term supply and in order to avoid renewed undersupply

    Side-effects in use of vitamin B12-supplements are not known to date. As the kidneys excrete excess B12, long-term and high-dosage intake may put heavy strain on the kidneys. Therefore, your vitamin B12-level should be measured before and during such long-term and high-dosage supplementation.

    Vitamin B12 - Test

    The American Journal of Clinical Nutrition could show how widespread vitamin B12-deficiency is in the USA alone. Out of the 325 million inhabitants, 39 percent suffer from a deficiency of this hormone. The question is how many of the people concerned are aware of their vitamin lack. The symptoms of vitamin B12-deficiency do not precisely indicate this state of deficiency. Hence, only low importance is accorded to it. Though, numerous groups are at risk.  [35]

    The present vitamin B12-supply can be determined by means of a blood test as blood in this case is the most effective medium. The parameter holotranscobalamin is the best one to measure. Holotranscobalamin is the form of vitamin B12 that is bound to proteins in the blood. It is the only form which can be used by all body cells. Due to this, it provides an optimum reflection of vitamin B12-levels.

    significance of holotranscobolamin blood levels

    Vitamin B12 deficiency test

    Apart from family doctors and alternative practitioners, you can easily test your vitamin B12 level at home. Order it from our webshop and send your blood sample to our specialist laboratory. After the analysis, you receive a comprehensive result report with recommended actions.

    Test vitamin B12 levels yourself

    The vitamin B12-level can easily be determined by means of the cerascreen® Vitamin B12-testkit. The test measures the concentration of the active vitamin B12 - the so-called holotranscobalamin - in your blood. As the laboratory parameters indicate empty vitamin B12-stores even before first symptoms occur, this constitutes the earliest indication of vitamin B12-deficiency. In many people, the holotranscobalamin blood levels are lower than 50 pmol/l due to their form of nutrition, life situation or underlying disease(s)

    The cerascreen® Vitamin B12-testkit in brief:

    • measurement of holotranscobalamin concentration in your blood
    • easy blood sampling in the comfort of your home
    • holotranscobalamin is the most significant parameter with regard to B12-analysis
    • only a small blood sample is needed
    • together with the result report, you receive individual recommendations for action

    Vitamin B12 and sports

    Micronutrients are essential for sports performance. We need them for energy production and are losing them in addition through sweating. This is especially the case for water-soluble vitamins like vitamin B12. These vitamins not only excreted via urine and stool, but also when sweating. Vitamin B12 is also needed for the formation of new cells, like e.g. the red blood cells and for the repair of damaged cells. [33]

    Vitamin B12 helps to get rid of sore muscles much faster!

    The task of cell renewal benefits above all the sore muscles. The torn muscle fibres can amongst others be built up again due to the cell repair function of vitamin B12. It alleviates the pain of the sore muscles and sports activities are no longer restricted. [33]

    Already normal physical activity can increase the demand for vitamins. Especially the vitamins and nutrients that are needed for energy supply must be taken up. [33]

    Scientific study concerning vitamin B12-deficiency in athletes has shown the following results:

    Keith and his colleagues found vitamin B12-deficiency in 33 % of female cyclists. [34] Steen and his colleagues determined in turn vitamin B12-deficiency in 80 % of female rowers. [35]

    Vitamin B12 and depressions

    Depressions are a more and more frequently occurring disease which affects both genders and can appear at any age. Vitamin B12 may be one cause of it. Long-term effects by means of vitamin B12 on the sensitivity of depressions could be measured. This means that long-term lack of vitamin B12 is more likely to cause depressions than in people with normal vitamin B12-levels. [36]

    Particularly often depressions occur due to prolonged or severe illnesses like e.g. strokes. In patients which already had a stroke, depressions could be decreased by additional intake of vitamin B12, folic acid and vitamin B6. [36]

    An overview of depression

    According to the World Health Organization (WHO), depressions are the main reason for inability to work - with rising tendency. Depressions are accompanied by mood swings, lack of interest, sleeping disorders, feelings of guilt, lack of concentration, disturbed self-perception and fluctuations of weight and appetite. Depressions can become chronic. In contrast to acute diseases, chronic diseases do not have a clear starting point but develop slowly and gradually over a longer period. At worst, depressions can lead to self-inflicted death (suicide). Annually, 850,000 deaths are associated with depressions. [37]

    Standard therapy methods of depression are the use of antidepressants. However, in more than 40 % of people suffering from depression this therapy has not achieved satisfactory results. Moreover, antidepressants have a variety of side-effects. These include reduced blood pressure, weight gain, digestive disorders or sexual dysfunctions. [38]

    Due to the difficult therapy and the constantly rising number of new cases, it is necessary to deal with preventive measures (prevention) and alternative therapies.

    Alternative therapies for depression

    Several micronutrients such as vitamin D, folic acid or omega-3 fatty acids have already been discussed for a long time in the context of depressions. Folic acid, for example, improves the function of brain and nerves. Due to a possible correlation between depressions and folic acid, a correlation with vitamin B12 was recognized.

    Vitamin B12 is heavily involved in folic acid metabolism as it influences the transformation of homocysteine into methionine. This methionine is in turn needed for the folic acid metabolism. Moreover, vitamin B12 - like folic acid - influences the function of the brain. In depressed patients also vitamin B12-deficiency was increasingly determined. Low vitamin B12-levels can amongst others be caused by various drugs such as e.g. anti-inflammatory drugs.  [37]

    Good to know: Therapy attempts with vitamin B12 resulted in a halving the risk to develop depression. This effect was measured in stroke patients over a period of seven years.

    Conclusion: Summarising the above, it can be said that vitamin B12-deficiency can increase the risk to develop depression. Therefore, the deficiency should be remedied promptly. In treatment of depressions the whole body and its nutrient supply, especially B-vitamins, folic acid and vitamin B12, should be considered.

    Vitamin B12 and dementia

    Low vitamin B-levels, especially vitamin B12-levels, are more and more often identified as risk factors for developing dementia. Vitamin B12-deficiency is associated with neurological changes. More precisely: Anaemia caused by vitamin B12-deficiency is related to neurological and psychotic symptoms such as cognitive impairments. Moreover, vitamin B12 can lead to an increased homocysteine level. A high homocysteine level is often found in people with dementia.

    An overview of dementia

    The German Alzheimer Association defines dementia as short-term memory loss, concentration problems or disturbances in spatial orientation over a longer period. According to a survey, 14 % of the over 70-year-olds and 37 % of the over 90-year-olds suffer from dementia. It has been observed that every 20 years the number of people suffering from dementia has doubled. It is expected that in 2020 the number of dementia patients will be 42.3 million and 81.1 million in 2040 worldwide. [39]

    Dementia can be caused by stress, burnout, mental stress, depression or changes in hormone balance, such as menopause. [40]

    Available studies on the treatment of dementia or the preventive effects of B-vitamins are inconsistent. However, the intake of folic acid below the daily recommendation of 400 mg can increase the risk of dementia especially in women. As vitamin B12 plays plays a major role in folic acid metabolism, sufficient supplies with this vitamin are recommended. [40]

    Conclusion: In spite of inconsistent scientific data, a possible correlation with vitamin B12 should not be underestimated. Especially in older people vitamin B12-deficiency occurs as the blood levels are influenced by anti-inflammatory drugs. A regular test of vitamin B12-levels is advisable to guarantee good cognitive skills in old age.

    Vitamin B12 and cardiovascular diseases

    Cardiovascular diseases can be related to several risk factors. Due to the multitude of possible risk factors it is difficult to define a single causal factor. The most prominent are high blood pressure, lipid metabolism disorders (high blood lipid levels), diabetes mellitus (blood-sugar illness) and smoking. Vitamin B12-deficiency due to its participation in homocysteine metabolism is discussed as another possible causative factor. [42]

    Homocysteine is a risk factor for cardiovascular diseases. It is broken down by vitamin B12 and transformed into methionine and thus used in folic acid metabolism. In case of vitamin B12-deficiency, homocysteine-levels are high as it cannot be broken down. [41] Homocysteine

    increases the risk to develop arteriosclerosis. Arteriosclerosis occurs by calcification of the blood vessels. This calcification leads to a narrowing of the vessels and increases the risk for heart attacks and strokes - which belong to cardiovascular diseases.  [42]

    Good to know: Cardiovascular diseases are responsible for one third of all deaths worldwide - with rising tendency.  [42]


    Vitamin B12 prevents high homocysteine blood levels and should thus be supplied in sufficient quantity as homocysteine plays a major role in cardiovascular diseases. Regular tests of vitamin B12-levels are thus essential.


    • Vitamin B12 is an essential vitamin which must be obtained from food or supplements.

    • Main tasks: Blood formation, protection of the nerve cells, cell division and support of folic acid metabolism.

    • Vitamin B12 is contained in animal-based foods. If vegetarian foods like seaweeds and mushrooms are suited to cover the demand, requires further research.

    • The risk group comprises pregnant and breastfeeding women, seniors and people suffering from gastrointestinal illnesses as they have an increased vitamin B12-demand.

    • Vitamin B12-deficiency can be associated with symptoms such as depressions, digestive disorders, anaemia, concentration problems as well as nervous disturbances.

    • The causes of vitamin B12-deficiency are manifold. Apart from the risk groups, gastric acid inhibitors, malnutrition, pure vegetable diets, stress and the lack of certain proteins may favor vitamin B12-deficiency.

    • This deficiency must be remedied by vitamin B12-rich foods, supplements or injections.

    • The best parameter for testing is holotranscobalamin.

    • The vitamin is essentially participating in physical performance and can play a role in the development of depressions, dementia and cardiovascular diseases.

    Reference list

    1. Kasper, H., Burghardt, W.: Ernährungsmedizin und Diätetik. Elsevier, Urban & Fischer, München (2014)
    2. Die ganze Welt der Vitamine, Mineralstoffe und Enzyme. garant Verlag GmbH, Renningen (2016)
    3. W. Kaim, B. Schwedersk: Bioanorganische Chemie – Zur Funktion chemischer Elemente in Lebensprozessen. Teubner (2005)
    4. Biesalski, H.-K., Grimm, P., Nowitzki-Grimm, S.: Taschenatlas Ernährung. Georg Thieme Verlag, Stuttgart New York (2017)
    5. Kon, S. K.; Porter, J. W. G.: The intestinal synthesis of vitamins in the ruminant. Vitamins and hormones.
    6. Degnan, P.H., Taga, M.E., Goodman, A.L.: Vitamin B12 as a modulator of gut microbial ecology. Cell Metab. 20, 769–778 (2014). doi:10.1016/j.cmet.2014.10.002
    7. Arens-Azevêdo, U., Pletschen, R. und Schneider, G.: Ernährungslehre: zeitgemäß, praxisnah. Bildungsverlag EINS GmbH., Köln (2011)
    8. Vitamin B12 | DACH Liga Homocystein,
    9. Myelin,
    10. Vitamin B₁₂,
    11. Institute of Medicine. Food and Nutrition Board: Dietary Reference Intakes: Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline, (1998)
    12. Froese, D.S., Gravel, R.A.: Genetic disorders of vitamin B12 metabolism: eight complementation groups – eight genes. Expert Rev Mol Med. 12, (2010). doi:10.1017/S1462399410001651
    13. Ärzteblatt, D.Ä.G., Redaktion Deutsches: Ursachen und frühzeitige Diagnostik von Vitamin-B12-Mangel,
    14. Toskes, P.P., Deren, J.J., Conrad, M.E.: Trypsin-Like Nature of the Pancreatic Factor That Corrects Vitamin B12 Malabsorption Associated with Pancreatic Dysfunction. J Clin Invest. 52, 1660–1664 (1973)
    15. Vitamin B12-Versorgung bei veganer Ernährung: So geht’s!,
    16. American Society for Microbiology,
    17. Monate, * Alle Preise verstehen sich zzgl der gesetzlichen MwSt Mindestlaufzeit 12: Lebenseinstellung - Veganer in Deutschland 2017 | Statistik,
    18. Nutrients | Free Full-Text | Prevalence and Predictors of Subclinical Micronutrient Deficiency in German Older Adults: Results from the Population-Based KORA-Age Study,
    19. Nahrungsergänzung,
    20. Office of Dietary Supplements - Vitamin B12,
    21. Folate, Vitamin B12, and Serum Total Homocysteine Levels in Confirmed Alzheimer Disease,
    22. Shane, B.: Folate and Vitamin B12 Metabolism: Overview and Interaction with Riboflavin, Vitamin B6, and Polymorphisms. Food Nutr Bull. 29, S5–S16 (2008). doi:10.1177/15648265080292S103
    23. Pschyrembel Online | Funikuläre Myelose,
    24. Are You Vitamin B12 Deficient?,
    25. Körner, U.: Ernährungsberatung in Schwangerschaft und Stillzeit. MVZ-Medizinverlage Stuttgart
    26. Watanabe, F., Yabuta, Y., Bito, T., Teng, F.: Vitamin B12-Containing Plant Food Sources for Vegetarians. Nutrients. 6, 1861–1873 (2014). doi:10.3390/nu6051861
    27. Watanabe, F.: Vitamin B12 sources and bioavailability. Exp. Biol. Med. (Maywood). 232, 1266–1274 (2007). doi:10.3181/0703-MR-67
    28. Ärzteblatt, D.Ä.G., Redaktion Deutsches: Vitamin-B12-Mangel durch Metformin,
    29. Kennedy, D.O.: B Vitamins and the Brain: Mechanisms, Dose and Efficacy—A Review. Nutrients. 8, (2016). doi:10.3390/nu8020068
    30. Butler, C.C., Vidal-Alaball, J., Cannings-John, R., McCaddon, A., Hood, K., Papaioannou, A., Mcdowell, I., Goringe, A.: Oral vitamin B12 versus intramuscular vitamin B12 for vitamin B12 deficiency: a systematic review of randomized controlled trials. Fam Pract. 23, 279–285 (2006). doi:10.1093/fampra/cml008
    31. Vidal-Alaball, J., Butler, C.C., Cannings-John, R., Goringe, A., Hood, K., McCaddon, A., McDowell, I., Papaioannou, A.: Oral vitamin B12 versus intramuscular vitamin B12 for vitamin B12 deficiency. Cochrane Database Syst Rev. CD004655 (2005). doi:10.1002/14651858.CD004655.pub2
    32. Read “Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline” at
    33. Vitamin-B12-angereichertes Zahngel für Vegetarier - BZfE,
    34. Vegane Ernährung,
    35. Tucker, K.L., Rich, S., Rosenberg, I., Jacques, P., Dallal, G., Wilson, P.W., Selhub, J.: Plasma vitamin B-12 concentrations relate to intake source in the Framingham Offspring Study. Am J Clin Nutr. 71, 514–522 (2000). doi:10.1093/ajcn/71.2.514