Iron is key to athletic performance, and a lack of iron can have a dramatic effect. So why do so few female endurance runners know the signs or solutions?
Avoid iron deficiency with the simple steps in our comprehensive guide.
How common is iron deficiency?
Iron deficiency in female athletes is surprisingly common. Studies have found the potential number of affected female athletes anywhere between 10 and 40 per cent.
Even athletes who appear to be performing well can be suffering from a moderate iron deficiency. University of Oklahoma Professor Emeritus of Medicine and haematology specialist E. Randy Eichner works with the University's sports teams and screens all incoming female athletes for anaemia. Year on year, Eichner finds that between 10 and 20 per cent of new female athletes have low iron levels.
Why is iron important for running?
Iron is important because the body uses it to create haemoglobin - the protein in your blood that carries oxygen. "This is obviously important for athletes because they need enough oxygen to get to their muscles to perform," explains Helen Heap, senior nutritionist at The Marilyn Glenville Clinic. (www.marilynglenville.com).
Why do female runners have low iron levels?
Women can be prone to iron deficiency if they have heavy periods and if their diet fails to provide sufficient iron. This can be caused by not eating enough iron rich foods and by consuming foods which inhibit iron absorption (tea and coffee are major culprits).
Men are at a very low risk of iron deficiency because they simply do not lose the volume of blood (and therefore iron) which women do.
Some researchers believe that running further increases the risk of iron deficiency due to loss of iron in sweat, urine and the gastrointestinal bleeding which occurs in a small percentage of long distance runners (around 7-30 per cent of marathon runners).
What are the symptoms?
After going for a blood test in 2005, 1500m World silver medallist Lisa Dobriskey discovered she had an iron deficiency. "I started to feel abnormally tired in training. I was even struggling with my easy runs and just didn't feel myself day to day. It was demoralising as the harder I tried, the worse I ran," says Dobriskey. Symptoms are wide-ranging but can include fatigue, muscle fatigue, breathlessness, pale skin, increased sensitivity to cold and hair loss.
Runnersworld.co.uk reader Eimear McCann experienced similar problems training for this year's Dublin Marathon. In the build up to the race she began to feel increasingly sluggish and slow, but a week before the race the problem became worse. "The exhaustion was all-encompassing and I managed just one seven mile run in the week preceding the big day," Eimear says. After visiting her GP she was diagnosed with a severe iron deficiency and had to withdraw from competing. "I was completely gutted after months of training," says Eimear, advising other women who experience similar unexplained symptoms to head for a check-up.
What should I do if I think I have an iron deficiency?
Head to your GP for a blood test. It might be tempting to self-diagnose and stock up on supplements but it's important to get an official diagnosis. "A blood test is recommended to rule out anything else and to find your actual level of iron. This is checked by measuring haemoglobin and ferritin," explains Heap.
Ferritin is a protein found inside cells that store iron and blood ferritin levels of less than 12 ng/ml indicate an iron deficiency. Heap warns against using supplements to dramatically up your iron levels without diagnosis - taking iron supplements could affect your body's ability to absorb zinc, another vital mineral. In addition, excess iron can be toxic, leading to a condition called hemochromatosis in which bodily organs become damaged by excessive stored iron.
For most people, simply increasing the iron rich foods you eat should be enough to avoid iron deficiency.
What treatments are available?
A range of iron treatments exist. Many GPs prescribe ferrous sulfate tablets - recovery using these takes six to eight weeks. Some people find ferrous sulfate tablets difficult to absorb and it can result in constipation, but alternatives do exist. Lisa Dobriskey uses Spatone, a natural supplement added to water, while nutritionist Heap recommends Biocare Iron Complex which is also easy on the digestive system.
How can I increase the iron in my diet?
Many runners stick to low-fat diets with chicken and fish centre stage, but eating enough iron is just as important as calorie counting. "On the face of it, I was eating a very lean and healthy diet, but I can see now that endurance running without iron in your diet can have debilitating consequences," says Eimear McCann. She has added red meat and leafy greens to her diet as well as using the Spatone supplement - and McCann hopes her marathon dream can be resurrected once she has made a full recovery.
The daily recommended amount for iron is 14.8mg for women. But you don't need to start chugging spinach like Popeye. There are a wide variety of iron-rich foods includes include liver, lean red meat, dried fruit, whole grains, spinach, watercress and curly kale. Find out how much iron the average portion of some of these foods contain here.
Boost your iron levels with plenty of fruit and vegetables - Vitamin C plays an important role in iron absorption.
Unfortunately, common vices including tea, coffee and alcohol inhibit iron absorption. Many fibre- and calcium-rich foods also dent absorption rates, but you don't need to ditch them from your diet altogether. Try iron- and fibre-packed whole grains instead, and avoid eating iron-rich foods at the same time as foods which prevent iron absorption.