Blood and rusty metal are both red in colour for the same reason — the strong attraction between iron and oxygen. These two naturally occurring elements — one a heavy metal and the other a gas found in the air — combine together to form red coloured compounds. In the human body the combination of these 2 elements is essential for life.
The main role of iron in the body is in the red blood cells. Here it combines with a protein to form a substance called haemoglobin. When we breathe in, oxygen in our lungs is attracted to the iron in haemoglobin and combines with it to form oxyhaemoglobin. This is transported around the body by the blood cells, and oxygen is released wherever it is needed to allow the conversion of carbohydrates (sugars) into energy. This is why blood in the arteries is bright red, whereas blood in the veins (which return blood to the heart and lungs for a further dose of oxygen) is darker in colour.
Lack of iron in the body is known as iron deficiency. It is easy to see how such a deficiency can cause a general lack of energy, and tiredness.
Iron deficiency can be due to inadequate amounts of iron in the diet and body stores, or to insufficient numbers of blood cells. The latter occurs after blood loss or when the production of blood cells is not working properly. When there is an inadequate amount of blood cells the condition is called anaemia.
As well as general tiredness and lethargy, iron deficiency can cause a number of other problems. If anaemia is present there may be shortness of breath, palpitations (rapid, or irregular, heartbeats) dizziness and lightheadness. Other symptoms include poor concentration and behaviour problems. This is particularly important in children. Those with an iron deficiency have been shown to have poor attention spans and poorer academic performance than their classmates. A spoon-shaped appearance of the fingernails (koilonychia) may occur in iron deficiency and soreness of the corners of the mouth and tongue may be present.
If iron deficiency is suspected it is confirmed by blood tests. The routine blood count will often be normal in the early stages, although the red blood cells may be smaller and paler than usual. However, specific tests for iron and its stored form, ferritin, usually give the answer.
When iron deficiency is found it is important to find the reason. A diet low in iron-rich foods (red meat, pulses, green leafy vegetables) may be the cause, but this is uncommon except in rapidly growing adolescents who are fussy eaters or vegetarians not paying attention to their diet. Drinking tea or coffee at meal times markedly decreases iron absorption, while eating foods rich in vitamin C increases the absorption of iron. In places of extreme poverty, lack of iron in the diet is a common cause.
Blood loss is a common cause in adults. Women with heavy periods frequently become iron-deficient. Where there is no obvious cause it is important to exclude ‘hidden’ bleeding from the intestine — stomach ulcers and bowel cancer can cause significant blood loss over a long period of time.
The management of iron deficiency consists of treating the cause (if one can be found), and replacing iron, either through a change in diet, blood transfusion (usually only necessary after sudden, heavy, blood loss), or taking iron in tablet (or, rarely, injection) form.
Last Reviewed: 21 September 2009