Vitamin B12, Brain and Psyche


Vitamin B12, Brain and Psyche

Vitamin B12, brain and psyche: vitamin B12 is vital for protecting the nerves and creating neurotransmitters/hormones. Vitamin B12 and mental health.

Vitamin B12 – Vital for the Brain and Psyche

Vitamin B12 is required for a number of biological processes that are essential to the central nervous system and for neural maintenance, and thus the vitamin has a major influence on the health of the brain and psyche. As a result, vitamin B12 deficiency does not only temporarily severely impair brain activity, but can also lead to long-term structural damage. 

The vital importance of this vitamin to the brain and psyche are further illuminated by some of the key benefits of B12 in this area, which include: 

  1. Supporting the development and protection of the neural connections in the brain
  2. Encouraging the synthesis of vital chemical messengers in the brain
  3. Counteracting various neurotoxic substances in the brain
  4. Regulating crucial cytokines in the central nervous system

In this way, B12 is intrinsically linked to mood, cognitive performance, memory, perceptions, coordination and many other fundamental processes in the brain. It is therefore today regarded as one of the most important vitamins for the psyche.

Vitamin B12 Deficiency – Psychological Symptoms

Vitamin B12 deficiency can lead to diverse psychological symptoms.  Among the most common are:

  • Dementia 
  • Memory loss
  • Cognitive decline 
  • Cognitive disorders
  • Severe poor concentration
  • Depression
  • Schizophrenia
  • Mania
  • Katatonia
  • Paranoia
  • Psychosis
  • Delusions
  • Delirium

Sometimes these symptoms can be fully or partially treated with vitamin B12 (1). It is important to bear in mind, however, that there are many alternative causes to these symptoms and that they are often triggered by a number of factors in combination. Consequently, taking B12 is not always effective.

These symptoms often occur before a B12 deficiency is clearly detectible in the blood, which is why the serum level for vitamin B12 is no longer considered a reliable marker (2, 3).

The Best Vitamin B12 Level for Mental Health

Many researchers are now of the opinion that the current recommendations for B12 are much too low. They are based solely on the symptom of anemia and do not take into account more recent findings on the extensive effects of the vitamin. 

Research has shown that the decisive factor for psychological symptoms is not the level of B12 in the blood serum but in the cerebrospinal fluid (4, 5). Various studies indicate that a sufficient concentration in the brain and spinal cord is only reached with B12 levels around 600 pg/ml (6).

This explains why psychological symptoms often occur long before the blood count changes or the conventional limits for B12 deficiency are reached (which define deficiency as a level of/below 200-300 pg/ml). 

In psychiatric patients, it is therefore advisable to both increase blood values above 600 pg/ml and reduce the secondary markers, methylmalonic acid and homocysteine.

Vitamin B12 and Neural Development 

B12 is particularly vital to the early development of the brain and nervous system in the womb and first years of life. If women are B12 deficient whilst pregnant or breastfeeding, it can lead to serious development problems in the child’s brain (7). 

Symptoms include:

  • Developmental delays
  • Anemia 
  • Loss of appetite 
  • Chronic vomiting
  • Weight loss
  • Low brain volume/atrophy
  • Palsy/cramps
  • Apathy
  • Irritability

The resulting damage is not always reversible, which is why an adequate B12 intake during pregnancy is critical. Especially women who are vegan/vegetarian, diabetic or have gastrointestinal problems should pay close attention to maintaining a good supply of the vitamin. This is often only possible with B12 supplements

How Effective is Vitamin B12 for Psychological Disorders and Illnesses?

The utilisation of vitamins and nutrients in general has unfortunately not yet found its place in standard psychiatric practice. This is all the more unfortunate when you consider the strong medications that are being prescribed more and more frequently that sometimes majorly interfere with the sensitive chemical balance of the brain, the long-term consequences of which are extremely questionable.

The scientific literature shows countless impressive case reports in which even the most severe mental disorders have been remedied with vitamin B12 alone. Also in the messages we have received from readers of this website, there are some very impressive experience reports. In some cases, the detection and treatment of a B12 deficiency can end many years of dependence on medicines or even institutionalisation. 

As described above, however, the causes of many mental disorders are complex; no nutrients can be considered a miracle cure in this context, mainly because there are often several deficiencies and factors present at the same time. This makes research all the more difficult. 

Methylcobalamin and Methylfolate

It is not yet clear through which mechanisms vitamin B12 has an effect on different mental health diseases. However, it is probably methylcobalamin that plays the key role here.

This theory is supported by the fact that vitamin B12 often only produces successful results if it is combined with methylfolate (L-5-MTHF, metafolin, quatrefolic).

Key Points: 

  • Vitamin B12 plays an important role in the health of the brain and psyche
  • Multiple psychological disorders can be triggered by B12 deficiency
  • B12 treatment can have dramatic success 
  • All natural B12 forms – methylcobalamin, adenosylcobalamin and hydroxocobalamin – play a role in this context; methylcobalamin is probably the most important 
  • Additional methylfolate may be required in some cases

Vitamin B12 for Psychological Symptoms 

The following dietary supplements can be recommended for mild psychological symptoms.


1000 µg 

Natural forms: methylcobalamin, adenosylcobalamin, hydroxocobalamin 


400 µg

L-5-MTHF, quatrefolic

For in-depth information on different vitamin B12 supplement dosages, click here

Below we will give brief overviews of the research into individual psychological diseases, exploring their connections to vitamin B12. 

Vitamin B12 and Depression

Low B12 levels have been associated with depression in several studies (8); improvements to treatment outcomes due to high B12 levels have also been reported (9). Various researchers have therefore repeatedly called for B12 to be given more focus in the field of depression research (10). 

In intervention studies however, B12 has not been shown to bring about any clear improvements, as demonstrated by a meta-analysis from 2015 (11). It is also possible, however, that insufficient doses and missing cofactors are behind these ambiguous results. In some cases, doses below 500 µg were administered, which are too low to be successful in the case of absorption disorders. On the other hand, recent research shows that depression is probably a sign of severe inflammation in the body and thus B12 is only one nutrient that can combat this.

In this context, one of the possible therapeutic workings of the vitamin is due to how it stimulates the production of SAM, which has a direct anti-inflammatory function and is proven to be very effective against depression (12, 13). Here B12 works in combination with folic acid and can only be successful when there are sufficient supplies of both vitamins.

This is further complicated by the fact that a large proportion of clinically depressed patients have a genetic mutation that interferes with the conversion of folic acid into active folate (14 -16). People with this so-called MTHFR mutation depend on an intake of folate in the active form methylfolate (L-5-MTHF), which has also been shown to be effective for depression (17). 

It would therefore be interesting to conduct studies which investigate the connection between B12 and methylfolate.

Vitamin B12 and Schizophrenia

Schizophrenia is a similar case (18). Here, vitamin B12 and methylfolate seem to have an interrelated effect (19). Deficiency of both B12 and folate leads to an increase in the homocysteine level in the blood. Several studies have identified an elevated homocysteine level as a major risk factor for schizophrenia. Here too, the above-mentioned MTHFR mutation plays a major role, and methylfolate (21, 22) has produced correspondingly good results in treatment (23).

Therapy with B12 and folic acid has brought clear improvements to the symptoms of schizophrenia in several studies (24, 26).

A study from 2016 showed that people suffering from schizophrenia had significantly reduced levels of methylcobalamin in the cerebrospinal fluid, while the fluctuations in the blood were far less pronounced. It is still unclear which mechanisms are responsible for the regulation of B12 in the brain, although it is suspected that the blood-brain barrier is disturbed. This observation supports the hypothesis that a lack of methylcobalamin is involved in the development of schizophrenia. 

Vitamin B12 and Psychoses

Psychoses are a recognised symptom of B12 deficiency; the connection has been known and well researched for almost 100 years – up to the exact presentation of the interrelated EEG abnormalities (27, 28). 

Psychoses caused by B12 deficiency respond well to the vitamin and can in some cases be completely treated (29, 30). It is astonishing that psychosis can be the symptom of a B12 deficiency. The vitamin can achieve better treatment results here than conventional anti-psychotic drugs (31). In this context, hydroxocobalamin has been shown to be as effective as methylcobalamin.

Here too, there are many indications that it is not the B12 concentration in the blood that is decisive, but that in the cerebrospinal fluid, as has already been discussed above in relation to schizophrenia (32). The exact mechanism however remains unclear.

Vitamin B12, Mania and Bipolar Disorder

The connection between B12 deficiency and manic symptoms is almost equally well documented. Numerous case studies show that severe manic conditions can be treated quickly and efficiently with the vitamin (33 – 36). 

While the exact correlation here remains unknown, the main cause is suspected to be damage to the myelin sheaths of the brain’s white matter (37). 

This theory remains under investigation, however, since the symptoms are reversible, which is unlikely in the case of structural myelin damage. 

Vitamin B12 and Dementia

The association between vitamin B12, dementia and Alzheimer’s disease has received broad scientific attention. Numerous studies have shown a statistical link between low B12 levels and the loss of cognitive abilities (38 – 40). It could also be shown that low levels of the vitamin precede the development of such diseases, although no causality has yet been proven (41, 42).

Unfortunately, the therapeutic potential of B12 in this area appears to be very limited, as there seems to be only a narrow timeframe in which B12 can halt cognitive decline. Several studies have shown that this timeframe is about 6-12 months after the onset of the first symptoms (43 – 45). 

After this period, the damage appears to be irreparable, at least with B12. Here, too, structural damage caused by a B12 deficiency seems to be decisive.

For an in-depth discussion of this topic, see the article: Vitamin B12 Deficiency and Dementia 

Vitamin B12’s Effect on the Psyche

All of vitamin B12’s functions probably play a major role in connection to mental health conditions, although it is not exactly clear which mechanisms are responsible for which symptoms.

However, it is likely that reversible symptoms such as depression or psychosis are primarily due to chemical interactions; whilst the irreparable nature of many forms of dementia tends to indicate the permanent destruction of nerves.


Vitamin B12 and Neurotransmitters

Vitamin B12 contributes in two ways to the synthesis and function of what are known as the monoamine neurotransmitters, which operate both as hormones and neurotransmitters (messengers in the nervous system):

  1. B12 stimulates the creation of tetrahydrobiopterin (BH4), an important coenzyme of neurotransmitter synthesis (46, 47)
  2. B12 is needed for the synthesis of methionine, which is further converted into S-adenosylmethionine (SAM) and also plays a role in the synthesis of some neurotransmitters (48 – 50)

Some of the neurotransmitters influenced by the vitamin are:

  • Dopamine
  • Adrenaline
  • Noradrenaline
  • Melatonin
  • Serotonin

In addition, vitamin B12 influences

  • Acetylcholine

All of these neurotransmitters and hormones perform important functions in the central nervous system and have a major impact on perception, mood and cognitive processing.

Vitamin B12 and Nerve Protection 

B12 deficiency can lead not only to chemical changes in the brain, but also to the permanent structural loss of nerves, brain mass and neuronal connections. Such damage cannot always be mended.

One of the main mechanisms for this is the B12-dependent regeneration of the myelin sheaths, a fat-rich protective layer around the nerve cords, which maintains nerve conductivity on the one hand, and protects the nerves from neurotoxic substances, radicals and toxins, on the other.

Both methylcobalamin and adenosylcobalamin are involved in the composition of the myelin sheaths.

A detailed discussion of this topic can be found in our article: Vitamin B12 and Nerves

Vitamin B12: Opponent of Homocysteine, MMA and Radicals

Vitamin B12 is also an important antagonist of some neurotoxic and/or pro-inflammatory substances, which include:

  1. Homocysteine
    Methylcobalamin promotes the conversion of homocysteine to methionine
  2. Methylmalonic acid (MMA)
    Adenosylcoabalamin encourages the conversion of MMA
  3. Nitrogen radicals
    Vitamin B12 – especially hydroxocobalamin – is a scavenger of nitrogen (NO) radicals and also regulates their synthesis (51, 52)
  4. Oxygen radicals
    Reduced cobalamin is a scavenger of superoxide and other oxygen radicals (53 – 55)

All of these substances either directly attack the nerves and brain, or promote chronic inflammations that lead to nerve damage. 

While for a long time these functions of B12 have received little attention, in the last 10 years they have moved more into focus. B12’s workings in this area should no longer be underestimated. 

Vitamin B12 and Cytokines

Fairly new is the discovery that B12 has effects that go way beyond its role as a cofactor in metabolic reactions. Several studies have shown that the vitamin has a hormone-like effect on special messengers called cytokines by down-regulating the levels of certain cytokines and raising those of others (56 – 59). 

The cytokines involved have important functions for the protection and preservation of nerves and the brain, for example by reducing inflammations or stimulating the production of radical scavengers.

Conclusion: Vitamin B12, Brain and Psyche

As numerous case reports show, B12 deficiency can have devastating effects on mental health. While in some instances the corresponding symptoms can be completely treated with the vitamin; more long-term deficiencies appear to cause permanent damage.

This illustrates the enormous preventive importance of maintaining sufficient B12 levels, as well as the fascinating therapeutic potential of the vitamin.

Groups at risk – such as vegetarians/vegans, pregnant and breastfeeding women, the chronically ill and the elderly – are strongly advised to take B12 supplements.


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