B12 deficiency

Your body needs vitamin B12 in order to create red blood cells and keep the nervous system healthy. It is also needed to absorb folic acid and it helps to release energy. B12 is absorbed through your intestines from a variety of foods, but mainly meat, fish and dairy products. It can be stored in the body in small amounts, and around 80% of this is stored in the liver. It may take three or four years for the symptoms of deficiency to develop.

Vitamin B12 cannot be absorbed on its own. It has to combine with another substance called 'intrinsic factor', which is produced by your stomach lining.

Vitamin B12 deficiency usually develops for one of the following reasons:

• Your stomach cannot produce enough intrinsic factor.
• Your intestine cannot absorb enough vitamin B12.
• You do not eat enough food containing vitamin B12 (this may happen to people following a vegan diet).

Glossary

Red blood cells

Red blood cells transport oxygen around the body and remove carbon dioxide

Liver

The liver is the largest organ in the body. Its main jobs are to secrete bile (to help digestion), detoxify the blood and change food into energy

Deficiency

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

Stomach

The sac-like organ of the digestive system. It helps digest food by churning it and mixing it with acids to break it down into smaller pieces