Iron Deficiency - Causes

What is iron and why do we need it?

Iron is a metal found widely in nature but it is also essential to a healthy body. It is used by the body to make haemoglobin which carries oxygen around the body in red blood cells and myoglobin which delivers oxygen to our muscles. It is also important for the healthy growth of hair, skin and nails. Experts are increasingly discovering how important iron is for the normal transmission of signals in the brain as well.

We get iron in our diet in two forms:

  • Haem iron, which is found in meat and fish.
  • Non-haem iron, which is found in vegetables and grains.

What causes iron deficiency?

You become short of iron for one (or a combination of) the following reasons:

  • You need more than your diet is providing.
  • You are losing more than your diet is providing.
  • You are not absorbing enough even though there is enough in your diet.

Your intake is not enough for your needs

This can happen if:

  • You are growing fast - so, for example, this is common in children and young people. Breast milk contains iron in a form that is extremely easy for a baby to absorb. However, once the baby is older than 4-6 months, breast milk simply doesn't contain enough iron for them anymore.
  • You are pregnant so need more iron than normal, as you have to make the cells for the developing infant.
  • Your diet doesn't contain enough iron. This is more likely to be the case if you don't eat any meat. However, vegetarians and vegans who have a well-balanced diet should be able to avoid iron deficiency. Even in meat eaters, the majority of iron in the diet comes from non-meat sources.
  • You diet frequently to try to lose weight.

You are losing iron from your body

For example, this can happen if:

  • You are having periods, particularly if they are heavy.
  • You have digestive problems such as acid reflux or a stomach ulcer.
  • You have a disease that causes your gut (bowel) to become very inflamed, such as Crohn's disease or ulcerative colitis.
  • You regularly take anti-inflammatory painkillers, such as ibuprofen.
  • You have frequent nosebleeds (epistaxes) or bleed from piles (haemorrhoids).
  • You have bleeding from your bowel that you can't see, such as is caused by colon cancer (although cancer usually also makes you anaemic).
  • You have worms in your gut - for example, hookworms.
  • You donate blood.
  • You have blood in your urine.
  • You have a skin condition that causes your skin to be shed much more than normal.
  • You are en endurance athlete.

Your body isn't able to absorb iron properly from your gut

This can happen if:

  • You eat or drink foods or beverages that interfere with the way iron is absorbed from your gut, such as phytates (found in high-fibre foods) and phenols (found in tea and coffee).
  • Calcium (which is contained in some medicines) also interferes with the absorption of iron.
  • You don't have enough acid in your stomach - for example, because you regularly take medicines to reduce stomach acid (such as medicines called proton pump inhibitors) or because you have had surgery to remove part of your stomach.
  • You have coeliac disease.

What other problems affect how your body deals with iron?

Some diseases can make you short of iron because the way that the body uses iron and moves it about in the body is altered by the disease, such as:

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Dr Jacqueline Payne
Peer Reviewer:
Dr Hannah Gronow
Document ID:
29400 (v1)
Last Checked:
26 May 2017
Next Review:
26 June 2020

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. Patient Platform Limited has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.