Iron deficiency anaemia is a condition where a lack of iron in the body leads to a reduction in the number of red blood cells. Iron is used to produce red blood cells, which help store and carry oxygen in the blood. If you have fewer red blood cells than is normal, your organs and tissues won't get as much oxygen as they usually would. There are several different types of anaemia, and each one has a different cause. Iron deficiency anaemia is the most common type. Other types of anaemia can be caused by a lack of vitamin B12 or folate in the body – read more about vitamin B12 and folate deficiency anaemia.