Anaemia, vitamin B12 and folate deficiency

Vitamin B12 deficiency anaemia or folate deficiency anaemia occur when a lack of vitamin B12 or folate means that the red blood cells that are produced by the body are abnormally large and cannot function properly.

The main symptoms of vitamin B12 deficiency or folate deficiency anaemia are:

• tiredness
• lethargy (lack of energy)

Anaemia

There are several different types of anaemia and each one has a different cause. This article focuses on anaemia that is caused by a lack of vitamin B12 or folate in the body.

Pernicious anaemia (an autoimmune condition where the body’s immune system attacks cells in the stomach) is the most common cause of vitamin B12 deficiency, and is also covered in this article.

The most common type of anaemia is iron deficiency anaemia, which occurs when the body does not contain enough iron to produce red blood cells.

See the Health A-Z topic about Iron deficiency anaemia for more information about this condition

Vitamin B12 and folate

Vitamin B12 and folate work together to help the body to produce red blood cells. They also have several other important functions:

• vitamin B12 helps keep the nervous system (brain, nerves and spinal cord) healthy
• folate is important for pregnant women because it reduces the risk of birth defects in unborn babies

Vitamin B12 is found in:

• meat
• eggs
• dairy products

The best source of folate is green vegetables such as:

• broccoli
• Brussel sprouts
• peas

How common is vitamin B12 deficiency or folate deficiency?

Both vitamin B12 deficiency and folate deficiency are more common in older people, affecting around 1 in 10 people who are 75 years of age or over. Vitamin B12 deficiency is rare in younger people, although those following a strict vegan diet (a diet that only contains food from plants) may be more at risk.

Pernicious anaemia, which is the most common cause of vitamin B12 deficiency, affects 1 in 10,000 people in northern Europe.

Outlook

Vitamin B12 deficiency anaemia can be treated with vitamin B12 supplements. Vitamin B12 is usually given by injection every other day for two weeks, followed by tablets until the deficiency is under control.

Folate deficiency anaemia can be treated with folate supplements. Folic acid tablets are used to restore folate levels, which usually need to be taken for four months.

Depending on the underlying cause of a vitamin B12 or folate deficiency, dietary improvements can prevent the condition returning, or supplements may need to be continued for life. 

Deficiency
If you have a deficiency it means you are lacking in a particular substance needed by the body.

Red blood cells
Red blood cells are cells in the blood that transport oxygen around the body.

Autoimmune condition
An autoimmune condition is when your immune system (the body’s defence system) produces antibodies (proteins) that should fight infections, but instead attack your body's healthy tissues.