Symptoms of a Vitamin B12 Deficiency

Indicators of a B12 Deficiency 

Symptoms of a Vitamin B12 Deficiency

Vitamin B12 Deficiency Symptoms: What are symptoms of a B12 deficiency? How do they arise? Why do they often go undetected?

This article aims to give an overview of the development and characteristics of vitamin B12 deficiency symptoms. The following questions will be addressed:


  • How can you recognize  the symptoms of a B12 deficiency?
  • How does the symptomatology of a B12 deficiency begin?
  • What can be done against each symptom?

Vitamin B12 Deficiency Symptoms

Vitamin B12 is an essential vitamin and cannot be produced by the body itself. Our bodies rely on a regular B12 intake through the diet. Vitamin B12 is stored in the liver, so a small shortage can be compensated for. It is only once the levels are significantly drained that the more severe symptoms will begin to manifest. Until this stage it is possible for years to pass as these symptoms develop.

Initial symptoms can be experienced as the body’s store of B12 begins to be used up. Because there is such a diverse range of initial symptoms, vitamin B12 deficiency often goes unnoticed.

B12 mangel symptome verlauf

This article should provide an insight into recognizing the signs that indicate a deficiency, so that a problem can be detected early on before more serious symptoms are experienced.

The Development of Deficiency Symptoms

So how do such symptoms emerge? Vitamin B12 is involved in a number of bodily functions, which can be broken up into five basic processes:

5 basic processes:

  1. Synthesis of DNA (cell division, blood formation)
  2. Energy metabolism (energy production in the mitochondria)
  3. Lipid metabolism (development of cell membranes, development of myelin sheath, protection of nerves in central nervous system and brain)
  4. Synthesis of hormones and neurotransmitters
  5. Detoxification (homocysteine, cyanide, nitrous oxide and many more)

A vitamin B12 deficiency impacts negatively upon all of these areas, giving rise to very varied symptoms. This helps to explain the enormous band width of vitamin B12 deficiency symptoms.

The Most Common Vitamin B12 Deficiency Symptoms

The following symptoms are among the most common:

  • Damaged energy metabolism (chronic exhaustion and tiredness, difficulty concentrating, muscle weakness)
  • Nerve damage (pain, numbness, tingling, paralysis, coordination difficulties, difficulty remembering)
  • Anemia (inefficiency, weakened immune system)
  • Impaired hormone and neurotransmitter metabolism (spiritual or mental difficulties, depression, psychosis)
  • Digestive problems (constipation, diarrhea)
  • Inflammations (mouth, stomach and intestine)

A complete list of vitamin B12 deficiency symptoms can be found at the end of this article.

What to do about Symptoms of a Vitamin B12 Deficiency?

If one or more symptoms of a vitamin B12 deficiency occur, it is advisable to check the body’s vitamin B12 status via a B12 urine test.

More information about this is available in our article vitamin B12 urine test.

When several symptoms occur, a vitamin B12 deficiency is most likely not far away. This should be treated urgently with corresponding supplements.

Here are our treatment recommendations for different symptoms. A full list of vitamin B12 symptoms can be found at the end of the article. 

Deficiency without symptoms250 µg of methyl- or hydroxocobalamin /day (oral) 
Light symptomslack of energy, exhaustion, mood changes, weakened immune system, diarrhea, torn mouth500 µg methyl- or hydroxocobalamin /day (oral) 
Severe symptomssleeping difficulties, confusion, numbness or tingling in extremities, paralysis, nerve pain, coordination difficulties, visual impairments

Initial treatment:
4 weeks 1000 µg Hydroxocobalamin/week (injection)
Continuation therapy:
500 µg methyl- or hydroxocobalamin /day (oral)



The following is important:

  • Symptoms of a vitamin B12 deficiency are hidden at first and worsen over time
  • A B12 deficiency is often incorrectly diagnosed
  • A vitamin B12 deficiency can be determined through the MMA test
  • Even with slight symptoms, B12 deficiencies should be rectified with vitamin B12 supplements

If Symptoms Occur: Urine Test for a B12 Deficiency

Unfortunately, symptoms of a vitamin B12 deficiency, particularly light symptoms but also more severe ones, are not properly recognized and thus handled incorrectly. Knowledge about the cause and risks of a vitamin B12 deficiency is still relatively new. Vitamin B12 tests were largely uncommon amongst doctors for a long time and it wasn’t until as recently as fifteen years ago that the concept of a vitamin B12 deficiency began to receive increasingly more medical attention, as a result of numerous studies, which have led to it being more commonly identified. 

Today, is has become incredibly simple to check one’s own vitamin B12 status at home, thanks to the development of the vitamin B12 MMA urine test. Upon discovery of one or more symptoms as listed in this article, it is advisable to carry out a urine test urgently in order to recognize a B12 deficiency as early as possible, thus avoiding the possibility of symptoms worsening.

Vitamin B12 Deficiency Symptoms and Misdiagnosis 

The reason why even the most severe symptoms of a vitamin B12 deficiency are often not associated with the vitamin straight away is because vitamin B12 performs such basic functions in the body that the corresponding symptoms have an enormous bandwidth. 

One way to help understand this is to picture the human body as a multi-story object. Vitamin B12 works right at the bottom of this, meaning that a deficiency in B12 works its way through every level, leaving the symptoms to be felt at the very top. When retracing to locate the cause of the symptoms, there are many other factors along the way which result in the same symptoms, leading to false assumptions as to what the cause could be. 

A vitamin B12 deficiency is still mistaken for several serious diseases and leads to common misdiagnoses. In all of the following cases, B12 status should be checked:

  • Multiple Sclerosis (MS)
  • Alzheimers/dementia
  • Autism
  • Fibromyalgia
  • Chronic pain
  • Chron’s disease
  • Paralysis
  • Chronic psychological illnesses (depression, paranoia, schizophrenia)
  • Impotence & infertility

Vitamin B12 Deficiency Symptoms – Unfortunately Non-Specific

Unfortunately, both severe and mild symptoms can be quite general, and so are often not classically associated with a B12 deficiency. The importance of both awareness and prevention of a vitamin B12 deficiency are relatively new concepts. As a result of a number of studies and increased medical attention, testing for deficiencies has also increased over the past 15 years and issues are now identified more frequently.

Because B12 is required for the most basic of bodily functions, a deficiency can resonate quite far. Vitamin B12 works on a very deep, ground level, whereas the symptoms of a deficiency typically appear on the surface. As a deficiency develops, there are a number of symptoms that can arise, that are often more commonly associated with other issues. As such, the shortage goes undetected, or an incorrect cause is identified.

Symptoms of a B12 deficiency are not unique, so there could be another cause. Simply suffering from the associated symptoms is not a sufficient diagnosis. If a deficiency is suspected then the relevant tests should be taken so that this can either be confirmed or ruled out. However, taking supplements as a precautionary measure will not cause damage in any circumstance as an overdose is not possible; excess vitamin B12 which is not required by the body is simply filtered out by the kidneys.

Symptoms of a Mild Vitamin B12 Deficiency

  • listlessness
  • problems concentrating
  • irritability
  • mood swings
  • feeling tense or nervous
  • immunodeficiency, weak immune system
  • constant fatigue and tiredness
  • weakness
  • inflammation of the mouth, stomach and intestine
  • cracks at the corner of the mouth
  • loss of appetite
  • shallow/pale complexion

Symptoms of a severe vitamin B12 deficiency

  • depression
  • anxiety
  • apathy
  • memory problem
  • disorientation
  • dementia
  • psychosis
  • hallucination
  • sleep disturbances
  • personality disorder
  • anemia
  • intestinal damage
  • nervous damage
  • muscle tremor
  • lack of coordination, unsteady gait, impaired fine motor skills
  • dizziness, fainting
  • feeling cold, tingling sensation and numbness
  • paralysis
  • arteriosclerosis
  • heart attack
  • stroke
  • impaired vision, retinal damage
  • spastic disorders
  • incontinence
  • infertility

Vitamin B12 Deficiency and Folic Acid (B9)

A lack of vitamin B12 can indirectly cause a folic acid deficiency, resulting in further symptoms. Metabolized folic acid/folate assumes the active form of tetrahydrofolic acid. For this process a specific enzyme is required, which in turn is dependent on the cellular presence of B12. Therefore, even with sufficient intake of B9, a folic acid deficiency can arise from a B12 deficiency.

The symptoms of a folate deficiency are very similar to those associated with B12, since the two vitamins often have similar features and uses. To an extent, a B9 supplement may even make up for a B12 deficiency. Typically this is the case for issues such as anemia, but often irreversible neurological conditions are less simply alleviated. Symptoms resulting from a folate deficiency include:

  • anemia, weakness, fatigue, difficulty concentrating, impaired blood formation, weakened immune system
  • disorders and inflammation of the oral and gastrointestinal mucosa, improper nutrient absorption, diarrhea, loss of appetite
  • underdevelopment of foetus’, babies and children; birth defects
  • irritation of the CNS, irritability, memory loss, anxiety, depression

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