Right back to childhood, when images of Popeye with his bulging biceps and spinach habit come to mind, we’re aware we need iron to keep us healthy. You might also be aware that, as women runners, we are a group that can be most susceptible to iron deficiency. But why do we need iron in the first place, how much do we need, and what happens if we don’t get enough?
Iron is a mineral, with women’s bodies containing around 3.5g. Its main role is in the production of red blood cells. Iron is a component of haemoglobin, the protein in red cells, which carries oxygen. Our red blood cells transport oxygen from our lungs to all our organs and tissues. Iron is also a component of myoglobin, a similar protein to haemoglobin, which binds and stores oxygen in muscles, ready for your more intense efforts. Iron is also involved in our hair, nail and skin formation, and in our immune defence system, too.
Iron is stored in the body as ferritin. When iron is needed, it travels to red cell production sites, attached to a protein called transferrin. Blood cell manufacture is largely carried out in the bone marrow and if iron levels are low, then red cell production is affected. The medical term for insufficient red blood cells is anaemia. There are different types of anaemia, but if the cause is a lack of iron, then the condition is called iron-deficiency anaemia. In the early stages of iron deficiency, you might experience tiredness, hair-loss, itchiness, a sore tongue, or cracked corners of your mouth. Once red cell production is affected, the symptoms become more extreme. Being anaemic can make you feel out of breath when you exert yourself. Your heart rate increases – at rest as well as during exercise – as the body tries to get the diminished numbers of red cells around the body as quickly as possible. You might get palpitations, feel light-headed and look very pale. And, of course, your running performance will also fall.
As women, we’re at increased risk of iron deficiency because of menstruation. Regular blood loss during a period can result in low iron levels and anaemia. The body is literally losing blood at a faster rate than it’s making it. This can happen gradually over months, or it can be a sudden drop if a period is very heavy. Pregnancy is also a common cause of iron deficiency. Iron stores are gradually depleted as the baby develops and may take many months to build back up again.
Women aged between 19 and 50 need 14.8mg of iron daily. Over the age of 50, requirements drop to the same as men (8.7mg daily).
The best place to get iron is from your diet. There are two types of dietary iron – haem iron and non-haem iron. Haem iron is most easily absorbed from the gut and is found in meat and fish. Liver, steak and the darker meat on poultry are all good sources of haem iron (avoid liver if you’re pregnant, due to high levels of vitamin A). Oysters are great, too.
Non-haem iron is less easily absorbed and can be found in pulses, nuts, dark green leafy vegetables such as kale, and fortified cereals. Consuming vitamin C alongside non- haem iron helps its absorption, so having a glass of orange juice with your cereal, or adding some broccoli to your lentil dhal will maximise the iron you get from it. Tea and coffee can hinder iron absorption.
If you think you may be anaemic, see your GP to discuss symptoms and, if necessary, arrange a blood test. If you’re anaemic, you may need more tests to find out why. If you have iron-deficiency anaemia, the most common reason in women is heavy periods and poor diet. However, it’s important not to self-treat with iron before establishing a cause. Sometimes iron-deficiency anaemia is due to serious underlying pathology, such as bowel cancer or a stomach ulcer, when blood slowly leaks into the gut, often unnoticed. Masking this by taking iron without being investigated is potentially life threatening. Other possible causes of iron- deficiency anaemia include coeliac disease and inflammatory bowel disease.
If you have a diagnosis of iron-deficiency anaemia and the cause has been identified, then you will probably be prescribed a high-dose iron supplement, much stronger than those you can buy over the counter.
Treatment aims to top up your iron levels, but also replenish your iron stores. This can take up to six months and you’ll need a repeat blood test to check everything is back to normal.
You may not be anaemic, but still have low ferritin levels. This suggests your iron stores are low and you are at risk of anaemia. Studies in 2003 and 2006 have shown that if women feel tired and have low ferritin levels, then a course of iron may improve their symptoms.
A Cochrane review in 2016 found menstruating women taking an iron supplement for at least five days a week had reduced prevalence of anaemia and iron deficiency. They also had less tiredness and improved exercise performance, compared with those who did not take iron. Side effects of taking iron can include constipation, diarrhoea, nausea and black stools.
If you’re fit and well, you should be able to get all the iron you need from your daily diet. If you think you might be anaemic, then you need a test. If you want to take a low-dose iron supplement, it’s unlikely to cause harm, but bear in mind the warnings above and always check with your doctor if you aren’t sure .