07.04.2022

Can regular and intense sport lead to iron deficiency?

women

Written by Justyna Wiraszka
Reading Time: 6 Minutes 

You exercise regularly and spend more than 10h a week engaging in sport activities. You watch what you eat, you limit sweets, snacks and alcohol intake. And yet, you still feel fatigue. Sounds familiar? If it does, one possible reason could be low iron levels. And while there are numerous articles online on iron deficiency, there is very little relevant information out there that addresses athletes and sportspeople in particular. 

Iron plays an important physiological role and is responsible for transporting oxygen and producing energy in the body. Unfortunately, despite their healthy and active lifestyle, athletes and sportspeople are often faced with iron deficiency. In fact, The International Olympic Committee 2009 Consensus  recommends regular screening for iron deficiency in athletes.  This is especially important since iron deficiency can lead to diminished endurance capacity and there are several mechanisms which have been suggested to be associated with an increased risk of iron depletion during exercise.

Before we dive into the actual cause of iron deficiency in athletes, let's establish some facts. We will start with what ferritin is and why it is important. We will walk you through the role of iron, what symptoms you might experience while being iron deficient and how to mitigate iron deficiency as a sportsperson. Shall we? 

What is ferritin and why is it important? 


Ferritin is a protein that supports storing iron in your body. Imagine ferritin as a sphere in which iron is kept. Ferritin is mostly found in the liver, spleen, bone marrow, and skeletal muscle, and to a small extent blood itself. The small amount of ferritin that circulates in blood is able to reflect or estimate the body's total iron stores. Testing ferritin is important because it allows you to assess how much iron is stored in your body. We have now established what ferritin is, but what about iron? 

What is iron? 


Iron is found in your red blood cells, where it is attached to hemoglobin. Together with hemoglobin, iron transports oxygen in the blood from the lungs to other tissues. Now, iron is also involved in red blood cell production and is required for a proper immune function. What is important to remember is that iron is not made by the body itself, but needs to be absorbed from your diet. To sum up:ferritin stores iron, and iron transports oxygen. 

What are the symptoms of iron deficiency? 

There can be a variety of symptoms related to iron deficiency. Common symptoms include pale skin, tiredness, cold hands and feet, dizziness, headaches, poor physical performance. However, iron deficiency can sometimes be “silent” i.e. it can occur in the absence of visible symptoms, and that is why it is crucial to regularly test for iron levels. We have now introduced to you the concept of ferritin, iron and iron deficiency symptoms. Let's now go into detail about the connection between sport and iron deficiency. 

Why are athletes at risk of iron deficiency? 

When we talk about risk of iron deficiency, we normally refer to ferritin levels lower than 30 ng/mL. As you can see on the image below there is a cut off of 30 ng/mL in our Bloom App, that is considered low ferritin level.

Ferritin Low Result

 

It is a well known fact that athletes are at a higher risk of iron deficiency as compared to the general population, or those with a sedentary lifestyle. There are multiple hypotheses of why athletes are at a greater risk of iron depletion. While the scientific community offers a variety of explanations, a general and widely-accepted consensus is yet to be agreed upon.

Firstly, one of the explanations is that, over a period of time, sport can affect your ferritin levels due to increased iron need and iron loss during heavy training. If the levels of iron are not compensated by iron supplementation or an iron-rich diet, it will result in low ferritin levels overtime. As this is just one of the proposed reasons why iron deficiency occurs in sportspeople, let's explore other proposed causes. 

One theory states that red blood cells break down faster in sportspeople. There are a variety of research papers reporting red blood hemolysis (breakdown) associated with different forms of exercise. In particular, the mechanical force called footstrike, which is how you land on your feet during walking or running, has been associated with red blood hemolysis. Some research describes the force associated with footstrike as a major cause for hemolysis. However, there is a wide range of literature stating that red cell hemolysis happens after various other forms of exercise, even without the footstrike force (e.g.swimming), thus pointing to a wider link between exercise and iron deficiency.  

One of the other proposed causes of sport-related iron deficiency –  elevated iron loss and a blockage of iron absorption – can be due to hepcidin bursts. The function of hepcidin is to regulate  the metabolism of iron. Several studies have explored the connection between hepcidin and various biomarkers during exercise. Since hepcidin is known to reduce iron absorption, it has (or can have)  an impact on iron stores during and after exercise. These studies have shown an increase of Hepcidin during days of intense exercise, which could in turn have an impact on iron stores during and after exercise. 

As you can see, there are various hypotheses of why iron deficiency can occur in athletes and there is no clear consensus among the scientific community. Consequently, regular check-ups provide valuable insights into athletes' health. But, even if your iron levels turn up to be low, there are a few things you could do in order to keep them in balance. Read on to learn more. 

How to mitigate iron deficiency as an athlete? 
 

One way to replenish iron levels is via your diet. It is crucial  to know that there are two forms of iron: heme and non-heme iron. Animal products have a heme form of iron, whereas plant products have non-heme. When planning iron-rich meals, it is important to remember about factors  which improve and disrupt iron absorption. For example, adding foods rich in vitamin C to your diet (for example fruits), while consuming iron-rich foods, can help improve the absorption of iron by the body. In contrast the consumption of milk products, coffee and tea inhibits iron absorption and should therefore not be consumed together with iron-rich foods (if the goal is to increase iron stores). 

Good sources of iron are liver, beef, fish, shellfish, potatoes, legumes, spinach, nuts and seeds. Recommendation on the exact amount of iron needed varies between organizations. According to the National Health Service (NHS) England, men over 18 years old need 8.7mg a day, while women aged 18 to 50 need around 14.8mg a day. The Institute of Medicine recommends 8 mg for men and postmenopausal  women and 18 mg for premenopausal women. If you want to take one step more toward having a well-balanced meal it is recommended to speak to a doctor about taking supplementation or to a dietician about making changes to improve your diet. However, before you take any further action, the first step should be to check your current iron store levels.

How is ferritin level checked? 


Serum ferritin is widely established in clinical practice as a marker, with low ferritin levels being indicative of iron deficiency, and elevated ferritin levels may be pointing to an iron overload. 

The Bloom Ferritin Test can be used to reflect  your body’s iron stores and check if your ferritin is at a low or high level, or within normal range. The test comes with a report that is available on your smartphone within a few minutes - including a personalized interpretation of the results and recommendations on how to combat your iron deficiency. 

Would you like to know more about the Bloom Ferritin Test? Read more about it here


References 

Hinton P. Iron and the endurance athlete. https://pubmed.ncbi.nlm.nih.gov/25017111/. Published May, 2014. Accessed March 29, 2022.

Anthl T. The International Olympic Committee (IOC) Consensus Statement on Periodic Health Evaluation of Elite Athletes: March 2009. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2742466/.
Published 2009, Access March 29, 2022. 

Petkus D, De Souzza M. The Unexplored Crossroads of the Female Athlete Triad and Iron Deficiency: A Narrative Review. https://pubmed.ncbi.nlm.nih.gov/28290159/. Published September, 2017. Accessed March 29, 2022.

Sumi D, Hayashi N, Yamaguchi K, Badenhorst CE, Goto K. Hepcidin response to three consecutive days of endurance training in hypoxia. Eur J Appl Physiol. 2021;121(4):1197-1205. doi:10.1007/s00421-021-04599-3 Published February, 2021. Accessed March 29, 2022.

Babić Z, Papa B, Sikirika-Bosnjaković M, Prkacin I, Misigoj-Duraković M, Katicić M. Occult gastrointestinal bleeding in rugby player. J Sports Med Phys Fitness. 2001 Sep;41(3):399-402. PMID: 11533573.

Hennigar SR, McClung JP, Hatch-McChesney A, et al. Energy deficit increases hepcidin and exacerbates declines in dietary iron absorption following strenuous physical activity: a randomized-controlled cross-over trial. Am J Clin Nutr. 2021;113(2):359-369. 10.1093/ajcn/nqaa289 Published November, 2020. Accessed March 29, 2022.

Córdova A, Mielgo-Ayuso J, Fernandez-Lazaro CI, Caballero-García A, Roche E, Fernández-Lázaro D. Effect of Iron Supplementation on the Modulation of Iron Metabolism, Muscle Damage Biomarkers and Cortisol in Professional Cyclists. Nutrients. 2019;11(3):E500. 10.3390/nu11030500 Published february, 2019. Accessed March 29, 2022.

Centers for Disease Control. Second National Report on Biochemical Indicators of Diet and Nutrition in the U.S. Population. Atlanta (GA); 2012. https://www.cdc.gov/nutritionreport/pdf/Nutrition_Book_complete508_final.pdfAccessed August 2, 2019.

Jameson JL, Fauci AS, Kasper D, Hauser S, Longo DL, Loscalzo J, eds. Harrison’s Principles of Internal Medicine. 20th ed. McGraw-Hill Education; 2018.

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