Steve Fennell, HCPC Registered Dietician
Iron is an essential mineral that has several important roles in the body, including oxygen transport. Anaemia is a condition in which the amount of haemoglobin or number of red blood cells (and consequently their oxygen-carrying capacity) is insufficient to meet the body’s functional needs.
How does iron deficiency cause anaemia?
There are several different types of anaemia, each with slightly different characteristics and causes, but iron deficiency is the most common cause of anaemia. It is defined as a decrease in the total iron content of the body, which can mean your iron levels are no longer sufficient for effective red blood cell production.
Signs and symptoms of anaemia
Although iron deficiency anaemia can have very few signs, the most common symptoms include:
- Feeling tired and lethargic
- Dyspnoea (shortness of breath)
- Your skin appearing paler than usual
If you’ve noticed a decrease in work capacity, difficulties breathing or problems affecting your immune system, this could point to iron deficiency anaemia.
What causes iron deficiency?
As the name suggests, iron deficiency anaemia occurs when there is not enough iron in the body. There are many reasons which can contribute to a state of iron deficiency, including:
- Blood loss from the gastrointestinal tract, which can be caused by non-steroidal anti-inflammatory drug use, peptic ulcers or carcinomas
- Menstruation blood loss
- Increased demands of pregnancy
Iron deficiency is the most frequently encountered nutritional deficiency in the world, with some 2 billion people estimated to be affected worldwide. Although its prevalence is highest in developing countries, iron deficiency anaemia affects a significant number in the developed world, with a prevalence of 2–5% among adult men and postmenopausal women. During childbearing years, there is a higher incidence of iron deficiency anaemia in women due to iron loss through menstruation and pregnancy, which can also result in complications during pregnancy.
Nonetheless, the modern western diet is rarely inadequate for iron provision unless there is a factor, such as those listed above, which results in an increased requirement.
Food sources of iron
Iron is present in food in two forms: haem and non-haem. Haem iron is derived mainly from meat sources, whereas non-haem sources of iron come from iron salts typically found in plant foods, such as beans, pulses and leafy greens.
Haem iron is better absorbed from the gut at a rate of around 15-20% compared to 5% for non-haem iron sources. Although some studies suggest vegetarians or vegans are more at risk of iron deficiency anaemia from a lack of meat in their diet, it is possible to attain enough iron via non-meat foods.
Iron rich foods include:
- dried fruit, such as raisins or prunes
- wholegrains, such as brown rice
- fortified breakfast cereals
- soybean flour
- dark-green leafy vegetables
- beans, pulses, nuts and seeds
How to absorb more iron from food
The degree to which iron is absorbed from the gut is also affected by interactions with other nutrients in food. Nutrients which influence iron absorption can be broadly grouped into two groups: promoters and inhibitors.
The most important promoters, which help increase the absorption of iron, include vitamin C (ascorbic acid), citric acid, and vitamin A, as well as the presences of meat.
Inhibitors, often one of a group of naturally occurring chemicals called polyphenols, calcium and phytates, decrease the rate at which your body absorbs some iron. Best-known examples include tannin, found in tea and coffee, and compounds found mainly in the husks of grains. Whilst this does not mean you should necessarily avoid foods with iron inhibitors, you should aim to limit your consumption at the same time as iron-rich foods.
What can be done to treat anaemia?
If you are concerned about your iron levels or are experiencing symptoms of iron deficiency anaemia, the National Institute for Health and Care Excellence (NICE) recommend you contact your GP. They may perform a verbal and physical examination or request a blood test to confirm the diagnosis.
Treatment usually involves taking iron supplements to replace missing iron and making necessary changes to address the underlying cause. If inadequate intake is suspected, advice may also be given on how to include more iron in your diet.