Hi guys, how are you? This is Gabi, nutritionist at Z2.

Did you know that iron deficiency is common, especially among athletes? But it's not normal! In this post I tell you more about mineral deficiency, prevention and treatment. Let's go!

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Iron is an extremely important mineral for athletes and cannot be produced by the body, therefore it must be obtained from external sources in the form of food or supplements. It has several functions in the body, including the transport and delivery of oxygen, energy production at the mitochondrial level and is also critical for cognitive and immune function - this demonstrates why iron is critical for performance and why a deficiency of Iron, which is not something uncommon, can have harmful impacts.

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Symptoms indicative of an iron deficiency include tiredness , lack of energy , shortness of breath , poor recovery and reduced performance (especially when the training load is constant or during a recovery phase).

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Why are athletes more likely to be iron deficient?
Athletes are at a higher risk of being iron deficient compared to the general population, especially female athletes, with up to ~35% being iron deficient versus ~5% in the general population.

Regular exercise can increase the likelihood of an iron deficiency and this is because there is an increased inflammatory response in the body post-exercise, which can decrease the body's ability to absorb iron for 3 to 6 hours after exercise. Inflammation increases levels of the hormone hepcidin, which is essential for iron regulation. When hepcidin levels increase, iron transport and absorption decrease. There is also potential loss of iron from exercise due to hemolysis (destruction of red blood cells), sweating, and gastrointestinal bleeding. Supplementation may be advised to prevent iron stores from declining further towards iron deficiency anemia, where performance can be seriously affected.

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What are the signs that you may be iron deficient?
Signs and symptoms of iron deficiency include tiredness, lethargy, fatigue, paleness and shortness of breath. Ideally, reduced iron stores should be detected before they are depleted in order to reduce the likelihood of any potential effects on performance and/or health. Early detection allows for immediate interventions (diet/supplementation) to prevent iron stores from declining further towards iron deficiency anemia.
During the early stages of an iron deficiency, when stores are reduced but not depleted, impacts on exercise performance are apparent. However, as iron stores become severely depleted, there is evidence to show that this negatively affects physical performance. Suboptimal iron stores will likely have a greater impact on performance in aerobic sports due to the effect of an iron deficiency on oxygen transport and delivery.

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How to test for iron deficiency?
Athletes should have their iron status evaluated by an experienced sports physician and a blood sample is required to test for a deficiency of the mineral.

Considerations must be made:
• The time of day – preferably in the morning.
• Hydration – athletes must be well hydrated.
• Previous exercise – 12-24 hours rest from exercise before blood sampling is preferable. If exercise is necessary, only low to moderate intensity exercise should be performed in the previous 24 hours. Exercise that damages muscles should not be done in the previous 2-3 days because this increases inflammation. Some of the proteins measured to identify iron deficiency are so-called “acute phase proteins” that respond to stress and inflammation. Therefore, the measurement may reflect stress or inflammation rather than an iron deficiency.
• Illness – the athlete must not show signs of illness or infection.
To diagnose iron deficiency, it is suggested, at a minimum, that serum ferritin , hemoglobin concentration and transferrin saturation be considered.

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How to prevent or treat an iron deficiency?

Strategy 1: Dietary Adjustments
A “food first” approach should be taken to prevent an iron deficiency. Iron requirements are higher for athletes compared to the normal population and therefore you must ensure that you are consuming sufficient amounts of dietary iron. A nutritionist can advise you on this by carrying out a dietary assessment.
However, the biggest problem with getting iron is not iron intake, but its bioavailability (how much of what we eat will actually be available in the body). The bioavailability of iron is generally low, and also depends on the source of iron. There are two forms of dietary iron which are heme and non-heme ; Heme iron is more easily absorbed in the intestine than non-heme iron. Foods of animal origin (e.g., beef, poultry, lamb, seafood, pork) contain a mixture of heme and non-heme iron, while foods of plant origin (e.g., legumes, green leafy vegetables, cereals, dried fruits and nuts) contain almost 100% non-heme iron. Absorption of non-heme iron is approximately 5% compared to ~40% for heme iron. These numbers may vary depending on the study, but in general heme iron appears to be absorbed 8 to 10 times better than non-heme iron.
In Western diets, iron obtained through heme sources constitutes about two-thirds of total iron stores, although only one-third of dietary iron intake is heme iron. The presence of heme iron in a meal can increase the absorption of non-heme iron, and therefore it is beneficial to include foods that contain both heme and non-heme in meals.
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Strategy 2: Oral Iron Supplementation
Supplementation is used after dietary adjustments if iron status does not improve or symptoms are still present (or sometimes used together, depending on the level of deficiency).
There are many different forms of iron that can be used in iron preparations; usually in the ferrous form (e.g., sulfate, fumarate, or gluconate), but sometimes ferric forms (e.g., citrate or sulfate) are used.
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Strategy 3: Intravenous (IV) Injections
To treat an iron deficiency, a doctor may give an intravenous injection of iron if oral and dietary therapy do not increase the serum level or if iron replacement is needed in a very short period of time. Additionally, it can be used if an athlete suffers from severe gastrointestinal problems due to oral iron therapy because it bypasses the intestine (where iron is absorbed).
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Once any of the above strategies have been initiated in an iron-deficient athlete, the iron level should be measured every 6-8 weeks. This allows for continuation of the chosen course of treatment or modification depending on the results. If iron deficiency is only moderate, iron status will need to be monitored less regularly; at least twice a year is recommended.

I hope you enjoyed it and remember to check your exams!

To the next,

Gabi.

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References:

Peeling P, Dawson B, Goodman C, Landers G, Trinder D. Athletic induced iron deficiency: new insights into the role of inflammation, cytokines and hormones. Eur J Appl Physiol. 2008;103(4):381-391. doi:10.1007/s00421-008-0726-6

Sim M, Garvican-Lewis LA, Cox GR, et al. Iron considerations for the athlete: a narrative review. Eur J Appl Physiol. 2019;119(7):1463‐1478. doi:10.1007/s00421-019-04157-y

Garvican LA, Lobigs L, Telford R, Fallon K, Gore CJ. Haemoglobin mass in an anaemic female endurance runner before and after iron supplementation. Int J Sports Physiol Perform. 2011;6(1):137-140. doi:10.1123/ijspp.6.1.137

Sim M, Garvican-Lewis LA, Cox GR, et al. Iron considerations for the athlete: a narrative review. Eur J Appl Physiol. 2019;119(7):1463-1478. doi:10.1007/s00421-019-04157-y

Björn-Rasmussen E, Hallberg L, Isaksson B, Arvidsson B. Food iron absorption in man. Applications of the two-pool extrinsic tag method to measure heme and nonheme iron absorption from the whole diet. J Clin Invest. 1974;53(1):247-255. doi:10.1172/JCI107545

Carpenter CE, Mahoney AW. Contributions of heme and nonheme iron to human nutrition. Crit Rev Food Sci Nutr. 1992;31:333–367.

Clénin G, Cordes M, Huber A, et al. Iron deficiency in sports - definition, influence on performance and therapy. Swiss Med Wkly. 2015;145:w14196. Published 2015 Oct 29. doi:10.4414/smw.2015.14196