Iron For Runners: Why It Matters And The Signs You May Be Low

Iron probably does not receive as much attention from runners as carbohydrates, protein or hydration, but it plays an essential role in both your health and your ability to exercise. One of its most important jobs is helping your body produce haemoglobin, the protein in red blood cells responsible for carrying oxygen around the body.

That makes iron particularly relevant to endurance runners. If your iron stores become depleted, you may begin to feel unusually tired, struggle with sessions that would normally feel manageable or notice that your running performance has declined without an obvious explanation.

However, feeling tired does not automatically mean that you are low in iron. Fatigue and poor running performance can have many causes, which is why taking an iron supplement simply because your running has suddenly become harder is not a good idea. If iron deficiency is suspected, the starting point should be appropriate medical assessment and blood tests rather than self diagnosis.

Why Is Iron Important For Runners?

Iron is required to make haemoglobin, which allows red blood cells to transport oxygen from your lungs to tissues throughout your body. It is also involved in energy metabolism and several other important functions.

For a runner, oxygen transport is particularly significant because aerobic exercise depends heavily on your body's ability to deliver and use oxygen. If iron deficiency progresses to iron deficiency anaemia, the reduced ability to transport oxygen can contribute to fatigue, breathlessness and reduced exercise capacity.

Iron status is not simply a question of whether you have anaemia, though. Your body's iron stores can become depleted before haemoglobin falls sufficiently for iron deficiency anaemia to develop, which is one reason appropriate blood testing and interpretation are important.

Are Runners More At Risk Of Iron Deficiency?

Iron deficiency can affect anyone, but athletes, particularly endurance athletes, can be susceptible to compromised iron stores. The reasons are more complicated than simply saying that running causes you to lose iron.

Runners undertaking high volumes of training may have greater iron turnover. Exercise also affects the way the body regulates iron. After exercise, levels of a hormone called hepcidin can increase temporarily, which may reduce iron absorption during the hours that follow. This is one of several reasons endurance athletes can require greater attention to their iron status, although most recreational runners do not need to start carefully timing every iron rich meal around their training.

Small iron losses can also occur through mechanisms associated with exercise, including sweat, gastrointestinal losses and the breakdown of red blood cells. Repeated foot strikes have sometimes been discussed as one mechanism contributing to red blood cell breakdown in runners, although iron status is influenced by many factors and it would be misleading to blame running impact alone.

Diet is another important part of the picture. Runners who are not eating enough overall, have a diet low in iron-rich foods or restrict particular food groups may find it harder to meet their requirements, especially during periods of heavy training.

Which Runners Are Most At Risk?

Runners who menstruate deserve particular attention because iron is lost through menstrual blood. Those experiencing heavy periods can be at greater risk of iron deficiency, and heavy menstrual bleeding is one of the recognised causes of iron deficiency anaemia.

Vegetarian and vegan runners may also need to pay closer attention to iron because plant foods contain non-haem iron, which is generally less readily absorbed than the haem iron found in animal foods. This does not mean that runners following a plant based diet will become iron deficient, but thoughtful food choices become more important.

Other runners who may be at increased risk include those completing particularly high training volumes, people who regularly donate blood and runners who consistently under-fuel. Athletes training at altitude also need sufficient iron because iron plays an important role in the body's response to reduced oxygen availability.

Previous iron deficiency matters too. If you have had low iron stores before, discuss with an appropriate healthcare professional whether your iron status needs to be monitored, particularly during periods of demanding endurance training.

What Are The Signs Of Low Iron?

One of the difficulties with iron deficiency is that many of its symptoms are not unique to low iron. Tiredness and a lack of energy are common signs of iron deficiency anaemia, but they can also result from hard training, inadequate sleep, illness, under-fuelling and numerous other causes.

Other symptoms of iron deficiency anaemia can include shortness of breath, heart palpitations, headaches and skin appearing paler than usual. Less common symptoms can include restless legs, changes to the nails, hair loss and unusual cravings for non-food substances such as ice.

For runners, an unexplained deterioration in training can sometimes be another reason to investigate further. If your normal running pace suddenly requires noticeably more effort, you are struggling to complete sessions you would usually manage or persistent fatigue is not improving with recovery, it is worth considering your overall health rather than simply assuming you need to train harder.

None of these symptoms can diagnose iron deficiency on their own. If you think you may be iron deficient, speak to your GP rather than trying to confirm it from a list of symptoms.

How Is Iron Deficiency Diagnosed?

Iron deficiency is assessed through blood testing. A full blood count can show whether you are anaemic, while other blood markers can help assess your iron status and stores.

You may hear runners talk particularly about ferritin. Ferritin is a protein that stores iron and measuring serum ferritin can provide useful information about the body's iron stores. However, interpreting ferritin is not always as simple as comparing your result with a number somebody has posted online.

Ferritin can be affected by factors including inflammation, and healthcare professionals may consider it alongside haemoglobin and other blood results as well as your symptoms and medical history. There is also debate within sports medicine about the most appropriate thresholds for athletes in different circumstances.

For that reason, avoid diagnosing yourself from somebody else's ferritin result or deciding that you need to achieve a particular number because another runner has been told something different. Blood results need to be interpreted in the context of the individual.

How Much Iron Do You Need?

In the UK, the NHS states that men aged 19 and over require 8.7mg of iron per day. Women aged 19 to 49 require 14.8mg per day, while the recommendation for women aged 50 and over is 8.7mg, although women who continue to have periods after 50 may require the higher amount.

These figures are general population recommendations rather than specific targets for every runner. Individual requirements and the risk of deficiency can be influenced by factors such as menstruation, diet, training and existing iron status.

Most people should be able to obtain the iron they need through a varied and balanced diet. If you are concerned that your diet may not be providing enough, a registered dietitian can help you assess your food intake without immediately turning to supplements.

What Are The Best Sources Of Iron?

Iron occurs in both animal and plant foods. Meat is a source of iron, while plant based sources include beans, chickpeas and other pulses, nuts, dried fruit and iron fortified breakfast cereals. This means runners can obtain iron from a wide variety of foods rather than relying on one particular source.

Fortified foods can be particularly useful because some breakfast cereals and other foods have iron added during production. Checking food labels can help you understand how much iron particular products contribute to your diet.

Variety is useful here. Rather than searching for one supposed superfood that will solve your iron intake, include a range of iron-containing foods as part of your normal meals.

Haem Iron Vs Non-Haem Iron

There are two main forms of dietary iron. Haem iron is found in animal foods such as meat and is generally absorbed more efficiently by the body.

Non-haem iron is found in plant foods and fortified products. Its absorption is more easily influenced by the other foods and drinks consumed around the same time, which makes meal composition particularly useful for runners relying heavily or entirely on plant sources.

This difference does not make plant sources of iron inadequate. It simply means that runners following vegetarian or vegan diets may benefit from paying more attention to both the amount of iron in their diet and the way iron-rich foods are combined with other foods.

Chickpeas are a great source of iron

Can Vitamin C Help You Absorb Iron?

Vitamin C can improve the absorption of non-haem iron. Combining plant sources of iron with foods rich in vitamin C is therefore a simple way of helping your body absorb more of the iron contained in a meal.

For example, you could combine beans or lentils with peppers or tomatoes, add fruit alongside an iron fortified breakfast cereal, or include other vitamin C rich fruit and vegetables as part of an iron-containing meal.

This is more useful than becoming obsessed with individual nutrients. A varied meal containing iron-rich foods alongside fruit and vegetables can provide several important nutrients at the same time.

Can Tea And Coffee Reduce Iron Absorption?

Tea and coffee contain compounds that can reduce the absorption of non-haem iron when consumed around an iron-containing meal. If you are trying to improve a low iron intake, it may therefore be useful not to routinely have tea or coffee at exactly the same time as your main iron rich meals.

If you have been diagnosed with iron deficiency, paying attention to what you consume alongside iron rich meals can therefore be useful. However, you do not need to become frightened of tea, coffee or dairy products simply because you are a runner.

The priority should be maintaining a varied diet that provides enough iron overall. If you have been prescribed an iron supplement, follow the instructions from your doctor or pharmacist because food and drink can affect how well some iron medicines are absorbed.

Should Runners Take Iron Supplements?

Iron supplements should not be treated like an ordinary sports supplement. More is not better, and taking additional iron when you are not deficient will not automatically improve your running performance.

If blood tests show that you have iron deficiency or iron deficiency anaemia, your GP or another appropriate healthcare professional can recommend the correct treatment. Iron tablets are commonly used to treat iron deficiency anaemia, and further blood tests may be required to check that treatment is working.

Iron supplements can cause side effects including constipation, diarrhoea, nausea and stomach discomfort. Excessive iron can also be harmful, which is another reason not to take high-dose supplements simply because another runner uses them.

Most importantly, finding iron deficiency should also prompt consideration of why it has occurred. Dietary intake may be relevant, but blood loss, heavy periods and gastrointestinal problems are among the other possible causes that may need investigation.

Will Taking Iron Make You Run Faster?

If you are iron deficient, identifying and appropriately treating the deficiency can be important for both your health and your ability to train and perform. Low iron status can affect your ability to exercise effectively, particularly if it progresses to iron deficiency anaemia.

That does not mean iron is a performance enhancer for runners whose iron status is already adequate. Taking additional iron does not give your blood an unlimited ability to transport oxygen, and unnecessarily increasing your intake is not a shortcut to becoming a faster runner.

This distinction is important because sports nutrition products are often marketed around performance. Iron should be viewed as an essential nutrient that needs to be maintained at an appropriate level rather than something you take in increasingly large amounts to improve race times.

Iron, Under Fuelling And Running

Low iron status can sometimes sit within a wider nutrition problem. Runners who consistently consume too little energy for the amount of exercise they are doing may also struggle to consume enough iron and other important nutrients.

This is one of the reasons simply adding an iron tablet may not address the underlying issue. If your overall diet is inadequate for your training, improving your general fuelling and energy intake may be just as important as focusing on an individual nutrient.

Persistent fatigue, declining performance, recurrent injuries and other changes should therefore be considered in the context of your overall health and training. If under fuelling may be an issue, seeking advice from an appropriately qualified sports dietitian or healthcare professional can be valuable.

When Should A Runner Speak To A Doctor?

Speak to your GP if you think you may have iron deficiency anaemia, particularly if you are experiencing persistent unexplained fatigue, breathlessness, palpitations or other symptoms associated with anaemia.

A runner whose performance has declined unexpectedly despite appropriate training and recovery may also want to discuss whether further investigation is appropriate. Do not assume iron must be the explanation, because infection, inadequate recovery, under fuelling and numerous medical conditions can also cause fatigue and poor performance.

If tests do show that you are iron deficient, follow the treatment and investigation recommended by your healthcare professional rather than relying on supplement advice from other runners or social media.

Final Thoughts On Iron For Runners

Iron is particularly important for runners because of its role in oxygen transport, energy metabolism and overall health. Endurance athletes can be susceptible to low iron stores, with runners who menstruate, follow restrictive diets, under fuel, donate blood regularly or undertake high training volumes among those who may need to pay particular attention.

Eating a varied diet containing appropriate iron rich foods is a sensible starting point, while combining plant sources with vitamin C can help improve absorption. Runners relying mainly on plant sources may need to give their iron intake a little more consideration, but a vegetarian or vegan diet does not automatically lead to iron deficiency.

Most importantly, do not diagnose low iron simply because you are tired and do not start taking high dose iron supplements in the hope of running faster. If persistent fatigue, breathlessness or an unexplained decline in performance makes you concerned about your iron status, get it properly assessed. Knowing whether you are actually deficient is far more useful than guessing.