Vitamin B deficiency

Vitamin B is a group of eight B vitamins. These are important for the metabolism, blood production and nerves, for example. The body is unable to produce B vitamins itself and has to absorb them from food. Eating a balanced diet is usually sufficient to prevent a deficiency.

At a glance

  • There are eight B vitamins in total. The most important of these are B1, B6, B9 (folate) and B12.
  • B vitamins are essential for humans. The body absorbs these vitamins from food.
  • If the body isn’t getting an adequate supply of one or more of these B vitamins, this is known as a vitamin B deficiency.
  • There is a wide range of symptoms, which differ depending on which B vitamin is lacking.
  • Eating a balanced diet normally ensures that the body gets all the vitamin B it needs.
  • Certain illnesses or an increased need for vitamin B (during pregnancy, for example) can cause a deficiency.
  • Taking vitamin B as a food supplement may make sense in the event of a deficiency.

Note: The information in this article cannot and should not replace a medical consultation and must not be used for self-diagnosis or treatment.

A table with a range of foods that are rich in vitamin B, such as pulses, cheese, eggs, mushrooms, milk, nuts and liver.

What is a vitamin B deficiency?

If the body isn’t getting an adequate supply of B vitamins, this is known as a vitamin B deficiency.

There are eight B vitamins in total, which are essential for humans. The body is unable to produce these itself and must absorb them from food. The most important B vitamins are B1, B6, B9 (folate) and B12.

B vitamins are important for the metabolism and blood production, as well as for the functioning of the nerves and the immune system.

The symptoms can differ greatly depending on which B vitamin the body is lacking.

Possible causes of a deficiency include certain illnesses, medication that restricts the absorption of B vitamins and following a restrictive diet. In addition, women have an increased need for vitamin B during pregnancy.

If the body doesn’t get an adequate supply of vitamin B from the diet, a food supplement may be necessary.

What are the symptoms of a Vitamin B deficiency?

The symptoms depend on which B vitamin the body is lacking.

A slight vitamin B deficiency often goes unnoticed. Symptoms only occur if the deficiency is more severe.

Signs of a vitamin B1 deficiency

Signs of a vitamin B1 deficiency include:

  • fatigue
  • disorientation
  • anxiety
  • cramps (e.g. in the calf muscles)
  • tingling or numbness in the extremities
  • paralysis
  • fluid retention (edema)
  • shortness of breath
  • fainting
  • gastrointestinal problems
  • weight loss

Signs of a vitamin B6 deficiency

Signs of a vitamin B6 deficiency include:

  • anemia
  • skin rashes
  • swollen, scaly lips
  • cracks at the corners of the mouth
  • an inflamed tongue
  • depression
  • seizures in babies

Signs of a vitamin B9 or vitamin B12 deficiency

Signs of a vitamin B9 or vitamin B12 deficiency include:

  • anemia
  • fatigue
  • pale skin
  • reduced stamina
  • depressive mood
  • forgetfulness
  • headache, dizziness
  • a yellowish skin tone
  • chest pain, breathing difficulties
  • mouth ulcers
  • tingling or numbness, especially in the legs
  • difficulties when walking
  • deformities in unborn babies
  • in babies: delayed development, low blood pressure, a tremor or seizures

What causes a vitamin B deficiency?

There are various causes of a vitamin B deficiency. These include:

  • older age
  • eating habits
  • certain illnesses
  • any medication the patient is taking
  • surgical procedures for weight loss
  • excessive alcohol consumption
  • increased need for intake during pregnancy

Older age

Older people are more likely to have a vitamin B deficiency. The reason for this may be that they are not eating enough or are not eating sufficient quantities of vitamin-rich foods.

Older people are more likely to have a vitamin B deficiency because they eat too little or don’t get enough vitamins in their diet, for example.

Eating habits

People who follow a vegan diet (excluding all animal-based foods) absorb virtually no vitamin B12 from their diet, which leads to a deficiency. Getting inadequate nutrition due to having an eating disorder like anorexia or following a restrictive diet is another possible cause of a deficiency.

In rare cases, newborn babies may also have a vitamin B deficiency. This happens if the mother herself has a vitamin B deficiency, meaning that the unborn baby doesn’t get a sufficient supply when developing in the womb and, later as a newborn, doesn’t get enough vitamin B from breastfeeding.

Certain illnesses  

Chronic bowel disorders, such as Crohn’s disease or celiac disease, can interfere with the body’s absorption of vitamin B. A chronic disease of the thyroid, such as Hashimoto’s thyroiditis, or an inherited inflammation of the gastric mucosa (gastritis) may also negatively impact the ability to absorb B vitamins.

People with rheumatoid arthritis need more vitamin B6, while people with a skin condition known as exfoliative dermatitis need increased levels of vitamin B9.


It is also possible that medication already taken by the patient is interfering with the body’s absorption of B vitamins, causing a deficiency. Drugs that may have this effect include stomach acid inhibitors and the active ingredient metformin, which is used to treat type 2 diabetes.

Surgical weight loss procedures

Bariatric surgery for obese (severely overweight) patients can cause a vitamin B deficiency. It involves using a gastric band or gastric bypass to reduce the size of the stomach – and, as a result, the person not only consumes fewer calories but also takes in less nutrient-rich food.

Excessive alcohol consumption

People who consume alcohol excessively often have a vitamin B deficiency. If the liver is damaged by alcohol, the body makes less efficient use of the vitamins it absorbs. In addition, some people who drink excessively tend to also eat a restrictive diet that doesn’t provide enough vitamins.

How common is vitamin B deficiency?

Vitamin B12 deficiency is the most common type of vitamin B deficiency. It occurs in 5 to 10 percent of people in industrialized countries. Around 20 percent of people aged over 60 have a vitamin B12 deficiency.

Vitamin B1 and B9 deficiencies are less common.

What are the consequences of a vitamin B deficiency?

The effect of a vitamin B deficiency on a person’s health depends on which B vitamin the body is lacking and on the severity of the deficiency.

Effects of chronic vitamin B1 deficiency

A chronic deficiency in vitamin B1 – a deficiency also referred to as “dry beriberi” – affects the central nervous system (CNS), comprising the nerve pathways in the brain and spinal cord. This causes symptoms including muscle wasting and gait abnormalities.

Dry beriberi includes a neurological disorder known as Wernicke encephalopathy. This causes a gradual loss of a patient’s mental capacities. If the disorder is left untreated and allowed to progress, it will become incurable at a certain point. Doctors refer to this as Wernicke-Korsakoff syndrome.

With “wet beriberi”, the deficiency impacts the cardiovascular system. The heart no longer works as normal and fluid builds up in the body’s tissues causing swelling (edema). This is a medical emergency that requires urgent treatment.

Effects of chronic vitamin B9 deficiency

Anemia is one of the symptoms of a deficiency in vitamin B9 (also known as folate).

In pregnant women, a deficiency can also cause harm to the developing fetus. Possible effects include deformities such as spina bifida, in which the spine doesn’t develop as normal, and miscarriage.

Important: Anemia can also occur as a result of a vitamin B6 or B12 deficiency.

Effects of chronic vitamin B12 deficiency

A deficiency in vitamin B12 can cause neurological disorders, such as funicular myelosis, a disease of the spinal cord.

In pregnant women, a vitamin B12 deficiency may also lead to low birth weights and premature births. If a deficiency in babies is not detected early enough, it may cause delayed development or permanent neurological damage.

How is vitamin B deficiency prevented?

A balanced diet provides the body with sufficient quantities of B vitamins.

A balanced diet provides the body with sufficient quantities of B vitamins.

Foods rich in vitamin B1 include whole grains, pulses, vegetables, fish and meat.

High levels of vitamin B6 are provided by wheat, whole grains, green vegetables, pulses, liver, fish, meat and egg yolks.

Green leafy vegetables, such as lettuce and spinach, tomatoes, oranges, cereals, liver and kidneys are all rich in vitamin B9 (folate).

Vitamin B12 is especially found in animal-based produce – in particular, liver, kidneys, scallops, fish, eggs, milk and dairy produce. Fermented plant foods like sauerkraut also contain B12 but in such small quantities that they don’t meet dietary requirements. As a result, people following a vegan diet should consult a doctor to determine whether they need to take vitamin B12 tablets as a supplement.

Experts recommend that women who are pregnant or planning a pregnancy should also take a folic acid supplement (folic acid is a synthetic precursor of folate, i.e. vitamin B9).

Anyone who is at an increased risk of a vitamin B deficiency should have their levels checked regularly. This applies in particular to those with Crohn’s or celiac disease. This enables early detection and treatment of deficiencies.

People who need to increase their intake of vitamin B – for example, because they have had a gastric band fitted – can prevent a deficiency with tablets or shots.

How is vitamin B deficiency diagnosed?

As the symptoms of a vitamin B deficiency vary widely and cannot always be clearly identified, doctors will start by asking detailed questions about the patient’s eating habits, any pre-existing conditions and any medication they are taking.

Laboratory tests – mostly blood tests – can confirm a suspected vitamin B deficiency.

However, a deficiency is often discovered by accident during a routine examination.

How is vitamin B deficiency treated?

To eliminate a vitamin B deficiency, it’s often enough to make some dietary changes and include more foods that are rich in vitamin B every day.

If this fails to work or is not possible as part of a vegan diet, tablets or infusions containing the lacking B vitamin are an option. A doctor can advise the patient on which supplement to take and on the correct dosage.

In addition, the causes of the vitamin B deficiency can also be treated if these are known.

In cooperation with the Institute for Quality and Efficiency in Health Care (Institut für Qualität und Wirtschaftlichkeit im Gesundheitswesen – IQWiG).

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