Iron deficiency is a prevalent issue among athletes, which can significantly affect training consistency and performance if left untreated. Where possible this should be fixed with good nutrition containing high iron foods that are easily absorbed and possibly the use of iron supplements. See these blogs to learn more (blog 1 and blog 2). In severe cases and in cases where the nutrition approach is ineffective the use of parenteral iron therapy (iron infusions or injections) may be considered and this is what we will explore in this blog.
Multiple mechanisms are related to iron loss during exercise, including sweating, gastrointestinal blood loss, haemolysis, and changes in iron regulatory hormone (hepcidin) that controls iron absorption from post-exercise feeding (1). As a result, there are numerous approaches to addressing an iron deficiency, ranging from dietary adjustments to oral or parenteral iron supplementation (2). However, the appropriate approach to addressing an iron deficiency is generally dictated by the severity of the issue.
Restoring iron status
Consumption of iron in food or via oral iron supplements can be used to address low iron stores, although the propensity of the gut to absorb iron via these approaches can be influenced by numerous factors, including exercise itself (3). Accordingly, studies emphasise the importance of timing iron consumption within 30 minutes of exercise (before or after) for optimal absorption (4, 5). Furthermore, morning intake seems more effective than afternoon, likely due to diurnal variations in hepcidin activity that impact iron absorption (4). In addition to issues with absorption at the gut, it might also be noted that it takes ~8-12 weeks of consistent oral supplementation to achieve significant improvements in iron status, and even then, the improvement may be small (i.e., oral supplementation over this period may only get an anaemic athlete back to an iron deplete (non-anaemic) state). Accordingly, for athletes with severe iron deficiency (anaemia), parenteral iron provision (i.e., infusions or injections) may be a viable solution, since it bypasses the limitations of absorption at the gut, and supplies iron direct in circulation
Consumption of iron in food or via oral supplements can be used to address low iron status. Whereas in athletes with severe iron deficiency, parenteral iron provision may be a viable solution.
Parenteral iron treatment (infusion or injection)
Parenteral iron administration through intravenous (IV) delivery has become an increasingly used approach to address an iron deficiency in athletes, with formulations having evolved over the last decade to offer safe doses into circulation in a single infusion. Formulations such as ferric carboxymaltose and ferumoxytol, have a favourable safety profile with limited serious adverse effects; however, intramuscular iron treatment, while effective, is a less favoured approach to IV iron administration, a result of negative indications such as pain, skin staining, and the potential for adverse impact on immediate post-treatment training or competition.
The efficacy of IV formulations in rapidly normalizing haematological parameters is a significant advantage, especially in severe cases of iron deficiency. For instance, a 300-500 mg dose of IV iron can increase serum ferritin levels by 200-400% (6), with peak ferritin concentrations occurring after 7–9 days and haemoglobin increasing within 2–3 weeks (7).
The impact of parenteral iron approaches on performance outcomes in athletes varies based on iron deficiency severity. In non-anaemic athletes, studies demonstrate that IV iron supplementation does not significantly enhance performance (8). Accordingly, efficacy on performance is notably greater in anaemic athletes with low pre-infusion serum ferritin concentrations (i.e., <20 ug/L; (9)).
The impact of parenteral iron provision is greater in anaemic athletes with low pre-infusion serum ferritin concentrations (i.e., <20 ug/L).
Long-term impacts and decay rates of serum ferritin following IV iron infusion vary among athletes, necessitating individualized follow-up and potential subsequent treatments (10). Research exploring the decay rates of serum ferritin subsequent to parenteral iron administration recommends blood screening at 4 weeks and 6 months post-infusion to assess the efficacy of approach on an individual basis (10). Furthermore, special considerations when using IV iron approaches must be given to compliance with anti-doping regulations, especially regarding IV infusion volumes (>100 mL per 12-hour period; (11)).
In summary, parenteral iron therapy is valuable for athletes, particularly in severe cases or when rapid repletion is required. However, indiscriminate use of IV iron is unwarranted, and therefore, this treatment approach should only be recommended and overseen by a trained medical physician ensuring compliance with any anti-doping regulations. Finally, an individualised approach to a specific athlete’s needs is essential for maximising benefits.
Webinar recording of Managing iron in athletes available on mysportscience academy
Peeling, P., Dawson, B., Goodman, C., Landers, G., & Trinder, D. (2008). Athletic induced iron deficiency: new insights into the role of inflammation, cytokines and hormones. Eur J Appl Physiol, 103(4), 381-391. https://doi.org/10.1007/s00421-008-0726-6
McCormick, R., Sim, M., Dawson, B., & Peeling, P. (2020). Refining treatment strategies for iron deficient athletes. Sports Medicine, 50(12), 2111-2123.
Barney, D. E., Ippolito, J. R., Berryman, C. E., & Hennigar, S. R. (2022). A Prolonged Bout of Running Increases Hepcidin and Decreases Dietary Iron Absorption in Trained Female and Male Runners. J Nutr, 152(9), 2039-2047. https://doi.org/10.1093/jn/nxac129
McCormick, R., Moretti, D., McKay, A. K. A., Laarakkers, C. M., Vanswelm, R., Trinder, D., Cox, G. R., Zimmerman, M. B., Sim, M., Goodman, C., Dawson, B., & Peeling, P. (2019). The Impact of Morning versus Afternoon Exercise on Iron Absorption in Athletes. Med Sci Sports Exerc, 51(10), 2147-2155. https://doi.org/10.1249/MSS.0000000000002026
McKay, A. K. A., Anderson, B., Peeling, P., Whitfield, J., Tee, N., Zeder, C., Zimmermann, M., Burke, L. M., & Moretti, D. (2023). Iron absorption in highly-trained runners: Does it matter when and where you eat your iron? . Under Review
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Baird-Gunning, J., & Bromley, J. (2016). Correcting iron deficiency. Aust Prescr, 39(6), 193-199. https://doi.org/10.18773/austprescr.2016.069
Woods, A., Garvican-Lewis, L. A., Saunders, P. U., Lovell, G., Hughes, D., Fazakerley, R., Anderson, B., Gore, C. J., & Thompson, K. G. (2014). Four weeks of IV iron supplementation reduces perceived fatigue and mood disturbance in distance runners. PLoS One, 9(9), e108042. https://doi.org/10.1371/journal.pone.0108042
Garvican, L. A., Lobigs, L., Telford, R., Fallon, K., & Gore, C. J. (2011). Haemoglobin mass in an anaemic female endurance runner before and after iron supplementation. Int J Sports Physiol Perform, 6(1), 137-140. https://doi.org/10.1123/ijspp.6.1.137
McKay, A. K. A., Goods, P. S. R., Binnie, M. J., Goodman, C., & Peeling, P. (2020). Examining the decay in serum ferritin following intravenous iron infusion: a retrospective cohort analysis of Olympic sport female athletes. Appl Physiol Nutr Metab, 45(10), 1174-1177. https://doi.org/10.1139/apnm-2020-0132
World Anti-Doping Agency. (2018). Intravenous infusions and/or injections. Retrieved 28 July 2023 from https://www.wada-ama.org/sites/default/files/resources/files/intravenous_infusions_v5.0_jan2018_en.pdf