Iron Deficiency and Running – How to Fix Low Ferritin?

Iron Deficiency and Running – How to Fix Low Ferritin?

Running can reduce the body's iron stores, especially in connection with long-term and intense running, because iron is released from the body through sweating.

Are you struggling with poor performance in running? The legs feel heavy and you feel short of breath? You're trying to come up with explanations for the complete fatigue that has gradually intensified. Or maybe you have always imagined that you just weren't born to run.

Do you also happen to be a woman and perhaps a vegetarian? Don't toss your running shoes in the trash yet – but measure your ferritin levels!

Iron deficiency is a common nutritional deficiency

Iron deficiency is one of the most common nutrient deficiencies in the world. In iron deficiency, the amount of iron in the body is reduced and more is lost than is supplied to the body from food. In iron deficiency anemia, the hemoglobin is low.

Women have been found to be more susceptible to iron deficiency than men. Up to a fifth of the world's women suffer from iron deficiency. This is due to menstrual bleeding and childbirth, and too little iron intake. In men, the prevalence of iron deficiency is usually lower.

What is iron deficiency without anemia?

When the hemoglobin is within the normal range, but the ferritin is low, it refers to 'iron deficiency without anemia', which has gained a lot of attention in recent years. In iron deficiency without anemia, the amount of stored iron has decreased, but it has not yet led to actual anemia. Despite this, you may suffer from vague symptoms that leads to the downfall of your running performance.

The discussion related to ferritin has in various contexts been labeled as just a fashionable disease, but in many contexts as a relevant factor causing real symptoms.

What is ferritin?

Ferritin is a blood marker indicating iron absorption and storage. It describes the amount of iron stores in the body. A low ferritin value can indicate an iron deficiency, while a high ferritin value can indicate, among other things, inflammatory processes in the body.

The generally accepted cut-off value for low ferritin is 30 µg/l, which indicates iron deficiency in adults.

What symptoms does iron deficiency cause?

Iron deficiency causes a wide variety of symptoms that are compatible with dozens of other illnesses. The most typical symptoms are:

  • exhaustion and unexplained tiredness
  • shortness of breath, feeling of a lump in the throat
  • muscle and joint aches, weakness, fatigue
  • cognitive symptoms such as brain fog, difficulty concentrating
  • depression, anxiety
  • fast heart rate, dysrhythmias, palpitations
  • hair loss, pallor
  • restless legs

Vague symptoms may be mistakenly diagnosed as e.g. thyroid problems, fatigue syndrome, fibromyalgia, depression or overexertion.

Is iron deficiency common in athletes?

According to research, athletes, especially women, are at risk for iron deficiency. Iron deficiency may be more common in athletes than in non-athletes because intense exercise and profuse sweating can cause iron to decrease from the body. In addition, athletes may have dietary limitations that can affect iron intake.

Causes of iron deficiency in athletes include:

  • diet: vegetarian or vegan, one-sided diet, insufficient energy intake
  • low quality iron, poor absorption
  • profuse sweating
  • an increase in hepcidin caused by hard training, which impairs iron absorption
  • step hemolysis in endurance runners

Iron deficiency can impair an athlete's performance and cause fatigue and weakness. However, you may not notice a mild iron deficiency.

Does running deplete iron stores?

Running can reduce the body's iron stores, especially in connection with long-term and intense running, because iron is released from the body through sweating. However, iron loss does not occur in all runners, and the effect of running on iron stores depends not only on the amount or intensity of running, but also on other factors such as diet and general health.

Step hemolysis in runners has been studied as part of research of sports and exercise-induced hemolysis. According to research, it is precisely running that causes a special wear of iron when the foot hits the ground. In particular, intense and long-lasting training, such as marathon running, increases the risk. A woman of fertile age who enjoys trail running and ultrarunning and prefers a plant-based diet has a high risk for iron deficiency.

Does corona virus affect iron values?

After the Covid pandemic, a lot of research has been done on the connection between the coronavirus and iron metabolism. The coronavirus infection can affect iron levels and it can cause iron deficiency. This is due to the inflammatory process caused by the infection and the release of iron from the body, as well as possible dietary changes that may occur during the infection.

I was diagnosed with iron deficiency three months after getting the corona virus. I suffered from long-term corona symptoms, but some of the symptoms were definitely symptoms caused by iron deficiency. The distinction is difficult, as both have similar symptoms. I had also experienced mild weakness, especially when trail running, even before getting the corona virus.

Both corona symptoms and iron deficiency made trail running difficult, my performance collapsed and my goals of even longer ultradistances had to wait for better times. It has been important to nurture a positive attitude, and I have taken the joy out of exercise whenever it has gone well.

Read also: Trail Running With Asthma - How to Run in Cold Weather?

How can you fix low ferritin levels?

What is the best way to fix iron deficiency? Correcting iron deficiency varies from person to person depending on the cause and severity of the iron deficiency. The most important ways to correct iron deficiency are:

1 Change to iron-rich diet

First of all, you should thoroughly check your own diet and eating habits. In particular, if you are a vegetarian or have practiced all kinds of diets, keto diets and paleo diets, you may have ended up eliminating all kinds of necessary nutritions from your diet.

An iron-deficient person should eat foods rich in iron, from which the iron is also absorbed. Iron from products containing heme iron is better absorbed than iron from products containing non-heme iron.

Good products containing heme iron include:

  • blood foods such as Finnish blood pancakes (may sound awful but they work)
  • liver dishes, especially pork liver and liver sausage containing pork liver
  • red meat, game
  • salmon, tuna

Good foods containing non-heme iron include:

  • whole grain products, such as rye bread, muesli (compare the nutritional contents)
  • tofu, soy products
  • green leafy vegetables such as spinach
  • beans, lentils, pumpkin seeds

Other nutrients affect the absorption of iron both favorably and by weakening it. When you want to enhance the absorption of iron, have also foods rich in vitamin C, such as peppers, broccoli and oranges. You can also take vitamin C as tablets.

Coffee, tea and calcium-rich foods, such as milk or calcium-added plant-based milk products, quark, yoghurt and cheese, weaken the absorption of iron. These are typically included in breakfast and snacks. It is therefore worth timing the eating of iron-rich nutrients, for example, in the evening or at another time when you do not consume products that impair iron absorption.

My own diet, avoiding ready-made meals, red meat and carbohydrates, included only tuna and salmon from the heme iron group, and rather limited whole grains and other iron-rich products from the non-heme iron group. And I mixed the low-iron foods with quark or yoghurt that I enjoyed with calcium-enriched coffee.

In the initial phase of fixing my iron deficiency, I prioritized the rapid recovery of iron stores more than anything else. I started eating those blood pancakes twice a week, grilled a huge slice of liver twice a month, and had four slices of rye bread with liver sausage a day. I also still ate plenty of uncooked vegetables (cucumber, bell pepper, lettuce, carrot, zucchini, tomato) a day and added a portion of pumpkin seeds and vitamin C-rich fruit and berries.

2 Iron supplement

In a severe stage of iron deficiency, iron supplements may be necessary. You can get an iron supplement in the form of tablets, liquids or by iron infusion. In healthy people, iron deficiency is mainly treated with oral products. If you are otherwise healthy, you can’t get too much iron by taking tablets.

My own iron deficiency was treated with 100 mg iron tablets, which are suitable for most people. For the first three months, the dose was two tablets per day, and after that one tablet per day. Fortunately, I didn’t get any adverse effects from the iron supplement.

I also take thyroid hormone twice a day, which cannot be taken at the same time as an iron supplement. Among vitamins and nutritional supplements, magnesium also weakens the absorption of iron.

When I had to take into account other medication and I wanted to maximize iron absorption by avoiding e.g. the effect of coffee and calcium, I wrote down a thorough meal schedule so that I’d know what to eat and when. It made life so much easier.

In addition to a change in diet and an iron supplement, the cornerstone of my treatment was adequate rest. Resting is difficult when your mind is drawn to the trails every day. However, running with an iron deficiency is frustrating, because it’s just poor performance after a poor performance. Dragging your feet can take the joy out of running for long periods of time.

I found a suitable pace of training, which meant trail running no more than every second or third day, and only five kilometers (3.1 miles) at a time. On other days, I took walks of different lengths.

Within four weeks of starting the treatment, my health improved, e.g. in the following ways:

  • total exhaustion eased
  • the humming in my ears stopped
  • my sight improved (this was probably corona)
  • brain fog subsided (coronavirus or iron deficiency)
  • my legs, which weighed a hundred kilos, became lighter and I could run again (and not just walk)
  • I was able to run 200 meters uphill again without feeling suffocated
  • resting heart rate fell close to normal (coronavirus or iron deficiency)
  • lethargy after training, PEM symptoms eased (corona or iron deficiency).

In three months, trail running already started to go as well as before, if not better. Likewise, general energy and mental energy had risen to a level where I no longer felt that I was feeling unwell. However, the longest I could still run was around 15 km (9.3 miles).

It took me five months to run my first half trail marathon. The next step is to get back into a normal running rhythm after the winter and try to run a trail marathon distance. And check my ferritin levels.

3 By eliminating the cause of iron deficiency

If the iron deficiency is caused, for example, by bleeding or some illness, the cause must first be determined so that the iron deficiency can be fixed.

Ferritin is easy and fast to measure. Low ferritin is usually a sign of iron deficiency, but high ferritin does not rule out the possibility of iron deficiency.

Iron deficiency is common and can reduce an athlete's performance to zero. Iron deficiency is usually relatively easy and inexpensive to treat, although it can take a long time to replenish iron stores. Sometimes iron tablets are not enough, but an iron infusion is needed.

If you suffer from symptoms suitable for iron deficiency and an iron supplement removes the symptoms, the cause of the symptoms was probably iron deficiency. However, you should not start taking iron supplements on your own, but always consult an expert.


Disclaimer: I’m not a medical professional, but I’ve been diagnosed and treated for iron deficiency. These are based on general research open to everyone and my own experiences.

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