@Canva.com: Poike by

When it comes to sport, symptoms such as fatigue, irritability and drop in performance are often associated with overtraining, stress or lack of sleep. But there could be another cause: iron deficiency.

Iron is an essential nutrient for our bodies. A lack of iron in our diet eventually leads to illness and can have a significant impact on our long-term health. Iron is a major component of haemoglobin and is responsible for transporting oxygen in the blood. It is also found in myoglobin and plays an important role in oxygen storage in the muscles. Together with vitamin B12 and folic acid, iron is necessary for effective and sufficient blood production. The regeneration of skin and hair, as well as immune system and thyroid function, are also dependent on adequate iron levels.

Our metabolism generally has a clever system to efficiently retain iron in the body. Nevertheless, people lose iron through blood loss (menstruation), sweat and skin abrasions. This iron loss must be replaced through food. However, this is not always possible: in Switzerland, around 20% of women already have an iron deficiency before reaching menopause. As a result, they are especially at risk due to the loss of blood from menstruation. In men, with the exception of adolescents, iron deficiency is far less common.

Prevention is key

A lack of iron will leave you feeling exhausted and lethargic. However, these symptoms may also be due to many other factors. If you suspect you might have an iron deficiency, it's crucial to get a proper test done first before taking iron supplements.

Prevention is key to preventing iron deficiency in the first place. This can be achieved through a varied diet that is rich in minerals, including iron. It should be noted that the bioavailability of heme iron (mainly found in animal-based foods) and especially non-heme iron (typically found in plant-based foods) is limited, making it difficult for us to absorb adequate amounts of iron through food. How much iron can actually be absorbed from food depends on numerous factors and varies greatly depending on the individual. Vegetarian endurance athletes in particular are at increased risk of iron deficiency due to the reduced absorption of dietary iron.

Regular monitoring is important

For dedicated athletes, it's a good idea to get regular blood tests and a detailed analysis of your iron levels from your GP. The most important values to check are ferritin, CRP (an indication of inflammation), haemoglobin, liver value and, if necessary, the thyroid gland. The threshold values for ferritin are interpreted in Switzerland as follows:

• Less than 15 ng/l = too low: A ferritin level of less than 15 nanograms per litre clearly indicates an acute iron deficiency, which is best treated with an infusion. If haemoglobin levels are also low, this is called iron-deficiency anaemia.
• 15-30 ng/l = insufficient: Ferritin levels between 15 and 30 ng/l are still very low but can be initially treated with optimised nutrition and iron tablets. If that doesn’t work, an infusion is also required.
• 30-50 ng/l = okay: Ferritin levels between 30 and 50 ng/l are okay, but not very high. Anything over 50 is good and does not need to be treated.

A new consideration in sport?

Endurance athletes need more iron in order for the bloodstream to adapt to the increased oxygen transport capacity during exercise, to encourage the production of red blood cells and to compensate for losses due to sweat or micro-damage in the gastrointestinal tract. A special consideration for dedicated athletes: intense physical activity increases the production of the hormone hepcidin, which inhibits iron absorption in the intestine. Hard training not only boosts hepcidin production but can also temporarily increase ferritin levels. Inflammation in the body also increases ferritin levels, which in turn results in a raised CRP value. It therefore makes no sense to interpret ferritin with a high CRP value.

Another special consideration in sport: People with an iron deficiency are usually slim and light, like most endurance athletes. Since the recommended daily amount of iron is around 15 mg, we should consume around 2,500 kilocalories a day in order to absorb enough iron. Many slim and light people, especially women, often do not meet this requirement, especially if they are trying to maintain the lowest possible weight at the same time – for example in running and cycling or aesthetic sports such as artistic gymnastics and figure skating.

Tablets or infusion?

So, what is the best treatment if you've been diagnosed with an iron deficiency? After optimising your diet, you will usually require long-term treatment with tablets. However, it takes around 2–3 months for the effects to be noticeable. Due to the increase in hepcidin after exercise, the tablets should be taken on recovery days rather than an exercise day. For long-term treatments, a low-dose treatment (less than 10 mg/day) is a good idea because the iron is better absorbed and leads to fewer side effects – such as diarrhoea and constipation – than high-dose iron tablets. Since the impact of the individual tablets and how they are tolerated can vary greatly from person to person, it can take a while before you find the right solution.

An infusion is only required in the event of a substantial iron deficiency. For athletes, the current doping regulations stipulate that any infusions whose volume is more than 100 ml are prohibited in sports. For competitive athletes, every infusion should be documented for safety reasons.

It’s important to identify the cause

Although iron deficiency is common in endurance sports, it should never be supplemented without a medical examination first. Even though it often happens that there is too little iron, there can also be too much. Iron overload can lead to liver damage, oxidative stress and an increased risk of cancer.