Vitamin B12 makes red blood cells in the body and keeps the nervous system healthy.
A lack of the vitamin can lead to vitamin B12 deficiency anaemia and cause the body to produce abnormally large red blood cells that can’t function properly.
The medical term for this is ‘megaloblastic anaemia’.
Anaemia is the general term for having fewer red blood cells than normal or an abnormally low amount of haemoglobin in each red blood cells.
Haemoglobin is the substance red blood cells use to carry oxygen around the body.
Vitamin B12 deficiency anaemia can cause many problems, including extreme tiredness and a lack of energy – otherwise known as lethargy.
If you constantly experience these symptoms, see a GP in case they are a sign of anaemia.
“It’s important for vitamin B12 anaemia to be diagnosed and treated as soon as possible,” said the NHS/
“Although many of the symptoms improve with treatment, some problems caused by the condition can be irreversible if left untreated.”
“The longer the condition goes untreated, the higher the chance of permanent damage.”
Other problems associated with vitamin B12 deficiency anaemia include pins and needles, mouth ulcers and a sore red tongue.
Muscle weakness, disturbed vision, psychological problems and problems with memory, understanding and judgement are also problems associated with the condition.
Symptoms usually develop gradually, but can worsen if the condition goes untreated.
Although uncommon, vitamin B12 deficiency anaemia can lead to problems with the nervous system, temporary infertility, heart conditions and pregnancy complications.
Adults with severe anaemia are also at risk of developing heart failure.
Some complications improve with appropriate treatment, but others – such as problems with the nervous system – can be permanent.
The most common cause of vitamin B12 deficiency anaemia is pernicious anaemia.
Pernicious anaemia is an autoimmune condition that affects the stomach, causing the immune system to attack the stomach’s cells.
This prevent the cells in the stomach from being able to absorb vitamin B12.
Some people can develop vitamin B12 deficiency anaemia as a result of not getting enough vitamin B12 from their diet.
Foods containing vitamin B12 include meat, salmon, cod, milk and other dairy products, eggs, yeast extract, fortified breakfast cereals and soy products.