B12 Deficiency

B12 deficiency is closely linked with pernicious anaemia. People with it are rarely anaemic in the usual sense – their symptoms come from low levels of vitamin B12.

What causes it?

There are two main causes, each accounting for roughly half of patients:

• Autoimmune (around 50%) – the body makes auto-antibodies that interfere with intrinsic factor in the stomach, which is needed to absorb B12.
• Poor absorption (around 50%) – problems in the stomach, such as too little or too much acid, or conditions of the intestine or bowel, stop B12 being absorbed.

Autoimmune diseases happen when the body produces something that harms itself. Examples include type 1 diabetes, lupus, systemic sclerosis, rheumatoid arthritis and Hashimoto’s thyroiditis.

Diet and recovery

B12 is found in foods such as eggs and meat. People with pernicious anaemia either can’t absorb vitamin B12 from their food, or don’t eat enough of it.

Once the deficiency is corrected, many people can lead a more or less normal life. However, many still have symptoms after correction, and many will need B12 replacement for life.

Read more about pernicious anaemia from the Pernicious Anaemia Society.

Make an enquiry