Did you know that low iron (i.e. iron deficiency (ID)) is a common contributor to the symptoms listed above? AND that iron deficiency is one of the most prevalent nutritional deficiency in the world1? Studies have demonstrated that 10–20% of menstruating women have iron deficiency, and 3–5% of them are also anemic. ID is most common in female athletes however; it is important to note that this problem also affects male athletes (up to 11% in some studies)2.
This is especially concerning when we consider that iron is needed by every cell and organ system in our body in order to function properly and sustain life. Iron plays a role in oxygen transportation, cellular repair, tissue healing and energy production, making it essential in achieving optimal performance.
Ferritin is the best measure of the iron stored in your body and it is measured with a simple blood test. The serum ferritin concentration is the most sensitive and specific test used for identification of iron deficiency. Recommended cutoffs for serum ferritin are highly varied. Many observational studies use <30ng/mL as a cutoff however some sources recommend serum ferritin be between 50-200ng/mL3. There is no real consensus for the optimal ferritin level. Instead, it would be reasonable to determine optimal ferritin levels be based on the individual: the type of exercise they perform, their training intensity and their current physical symptoms.
Here’s the kicker though: The cutoff for “normal” ferritin can be as low as 5 ng/mL depending on the lab used and the age of the client4. For example, the reference range for a female >18 years of age is 5-247ng/mL. That is a huge range with an incredibly low cutoff for deficiency. This happens because the “normal” ranges given on a standard laboratory report are not representative of the requirements needed for optimal health and instead, are constructed based on range in which 95% of the population would fall. 95% of our population in which many are deficient…doesn’t really make sense. So, even if your lab printout reads that your ferritin is ‘normal,’ it may in fact be too low to support your needs.
There are 2 main types of iron deficiency.
1. Iron deficiency (ID) without anemia: sub-optimal serum ferritin levels but hemoglobin levels remain normal.
2. Iron deficiency anemia (IDA): a later manifestation of ID in which there are sub-optimal serum ferritin levels AND low hemoglobin (≤ 130 g/L in males and ≤120 g/L in females)
Both types of iron deficiency can affect performance and should therefore be addressed. Both ID and IDA have been demonstrated to negatively affect physical and cognitive function in athletes5,6. With either presentation, athletes may suffer from fatigue, low energy, poor recovery, chronic injuries and declining cognitive and physical performance5,6. When an iron deficient athlete attempts to train at their typical intensity, despite being in a deficient physiological status (i.e. not having enough gas (iron) in the tank), it sets the stage for developing an overuse injury. If your body is lacking a nutrient that is essential for full recovery between training sessions, injury is likely to ensue.
Iron deficiency occurs due to a discrepancy between use and intake/absorption of iron. We lose and utilize iron on a daily basis through normal physiological processes. Females lose additional iron through menstruation. Athletes lose additional iron through processes related to exercise and inflammation. Additionally, young athletes have higher iron requirements as they expand their blood volume as a part of normal growth.
To account for these loses, we need an appropriate intake of iron. We get iron through our diet in two forms. Iron that comes from meat, poultry and fish, called heme iron, is the easiest for the body to absorb and utilize. Some plant products and fortified foods also contain iron, called non-heme iron, but this type of iron is harder for the body to absorb and utilize. Because non-heme iron is harder for the body to absorb and use, the recommended daily intake of iron for vegetarians is almost 2x that recommended for athletes who eat meat7!
When iron losses exceed absorption or absorption falls below demand, iron stores become depleted, resulting in a reduced ferritin level. Eventually, the stored iron is too low to provide the tissues with sufficient iron and symptoms arise.
Figure 1 below summarizes many of the factors that impact your overall iron status.
Figure 1: Factors influencing iron stores
* Metabolic processes: refers to the various chemical processes that occur within your body in order to maintain life.
If you are an elite, endurance athlete, the International Olympic Committee recommends routine hematological screening for iron deficiency based on the “higher than expected presence of decreased iron stores in athletes”. If you think that you may be iron deficient, you should see your family doctor or naturopathic doctor to further investigate
If you find yourself with ID +/- symptoms, it is important that you find a practitioner who is experienced in functional medicine and knowledgeable about female athletes (naturopath, medical doctor, sports medicine doctor etc). Find someone who is knowledgeable and experienced and can provide you with effective solutions to help optimize your health. Replenishing your iron stores many mean supplementation, dietary modification, temporary activity modification, optimizing your gut health, normalizing your menstrual function etc. Your practitioner should ask you questions about each of these contributing factors and work with you to create an individualized plan! In cases where ferritin levels are extremely depleted, or with iron deficiency that does not respond to dietary changes, training modifications and supplementation, injections may be required to replenish iron stores.
Iron deficiency is common and most prevalent in female athletes. Symptoms may include fatigue, low energy, poor recovery, unexplained pain, persisting injuries. Be suspicious, get tested and work to optimize your physiological status if you find yourself in this situation. Iron deficiency is all too common, under recognized and has huge implications, especially for female athletes.
References and Resources:
Chapter 4: Childhood and maternal undernutrition. (2010, November 02). Retrieved August 5, 2019, from https://www.who.int/whr/2002/chapter4/en/index3.html
Soppi ET. Iron deficiency without anemia - a clinical challenge. Clin Case Rep. 2018;6(6):1082–1086. Published 2018 Apr 17. doi:10.1002/ccr3.1529
Sim, M., Garvican-Lewis, L.A., Cox, G.R. et al. Eur J Appl Physiol (2019) 119: 1463. https://doi.org/10.1007/s00421-019-04157-y
Briden, L. (2018). Period repair manual: Every womans guide to better periods. Sydney, N.S.W.: Macmillan.
Reference Ranges SECTION (HCP- Reference Ranges Page). (n.d.). Retrieved August 5, 2019, from https://www.lifelabs.com/page-section/reference-ranges-section-hcp-reference-ranges-page/
Camaschella C. 2015. Iron‐deficiency anemia. N. Engl. J. Med. 372:1832–1843. Retrieved August 5, 2019.
Lopez A., Cacoub P., Macdougall I. C., and Peyrin‐Biroulet L.. 2016. Iron deficiency anaemia. Lancet387:907–916. Retrieved August 5, 2019.
Office of Dietary Supplements - Iron. (n.d.). Retrieved August 5, 2019, from https://ods.od.nih.gov/factsheets/Iron-HealthProfessional/
Ljungqvist A, Jenoure P, Engebretsen L, et al The International Olympic Committee (IOC) Consensus Statement on periodic health evaluation of elite athletes March 2009 British Journal of Sports Medicine 2009;43:631-643.
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