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Vitamin B12 is essential for life. It is needed to make new cells in the body such as the many new red blood cells which are made every day. Vitamin B12 is found in meat, fish, eggs and milk but not in fruit or vegetables. A normal balanced diet contains enough vitamin B12. A lack of vitamin B12 leads to anaemia and other problems.

What is anaemia

Anaemia means that you have fewer red blood cells than normal or you have less haemoglobin than normal in each blood cell.

In either case, a reduced amount of oxygen is carried around in the blood stream. There are various causes such as lack of iron or other vitamins.

Symptoms of B12 deficiency

Due to anaemia

These symptoms are caused by the amount of oxygen in the blood.

  • They include tiredness, lethargy, feeling faint or becoming breathless.
  • Less common symptoms include headaches, palpitations, altered sense of taste, loss of appetite and ringing in the ears (tinnitus).
  • You may look pale.

Other symptoms

Cells in other parts of the body may be affected as well as your blood when you lack vitamin B12. Other symptoms that may occur include a sore mouth and tongue.

If left untreated, problems with nerves and psychological problems can develop. Psychological problems may include depression, confusion, difficulty with memory or even dementia. Nerve problems may include numbness, pins and needles, vision changes and unsteadiness.

Causes of B12 Deficiency

Pernicious anaemia

Normally when you eat foods with vitamin B12, the vitamin combines with a protein called intrinsic factor in the stomach. The combined B12 and intrinsic factor is then absorbed further down the gut at the end of the small intestines. (Intrinsic factor is made by cells in the lining of the stomach and is needed for Vitamin B12 to be absorbed.)

If you have pernicious anaemia, antibodies are formed against your intrinsic factor, or against the cells in your stomach which make the intrinsic factor. It is thought that something triggers the immune system to make the antibodies but the trigger is not known.

Pernicious anaemia usually develops over the age of 50. Women are more commonly affected than men and it tends to run in families. The antibodies which cause pernicious anaemia can be detected by a blood test to confirm the diagnosis.

Stomach or gut problems

Various problems of the stomach or gut can be a cause of of vitamin B12 deficiency.

  • Surgery which removes the stomach or the end of the small intestine.
  • Diseases of the lower bowel such as Crohn’s disease
  • Conditions of the stomach which affect the production of intrinsic factor


Some medicines used for other conditions may affect the absorption of vitamin B12. The most common example is metformin a medicine used for diabetes. Some anticonvulsants used for epilepsy may also have an effect.

Dietary causes

A normal balanced diet should give you enough Vitamin B12. Strict vegans who eat meat or dairy products may not eat enough B12. Some foods are fortified with vitamin B12 for example some breads and breakfast cereals.

Diagnosis of B12 deficiency

The level of vitamin B12 can be measured by a blood test. Further tests can then investigate the cause. This can be done by your family doctor.


Vitamin B12 injections. Normally about six injections are given at first to build the levels up quickly. An injection is then given once a month.

So, if you are experiencing any of the symptoms the good news that simple treatment can make you feel so much better!

The Core Team

Dawn Blythe

Clinic Director, Practice Midwife

Yvonne Evans

Clinic Director, Nurse

Dr. An Croonenborghs

General Practitioner

Jane Evans