Iron is an extremely important mineral for athletes and cannot be produced by the body, so it must be obtained from external sources in the form of food or supplements. It has several functions in the body, including the transportation and delivery of oxygen, energy production at the mitochondrial level, and is also crucial for cognitive and immune function—this shows why iron is critical for performance and why an iron deficiency, which is not uncommon, can have harmful impacts.
Symptoms indicative of iron deficiency include fatigue, lack of energy, shortness of breath, poor recovery, and reduced performance (especially when training load is constant or during a recovery phase).
Why are athletes more likely to have iron deficiency?
Athletes are at a higher risk of iron deficiency compared to the general population, especially female athletes, with up to ~35% having an iron deficiency versus ~5% in the general population.
Regular exercise can increase the likelihood of iron deficiency because there is an increased inflammatory response in the body post-exercise, which can reduce the body's ability to absorb iron for 3 to 6 hours after exercise. Inflammation increases levels of the hormone hepcidin, which is crucial for the regulation of iron. When hepcidin levels rise, iron transport and absorption decrease. There is also potential iron loss due to exercise through hemolysis (destruction of red blood cells), sweating, and gastrointestinal bleeding. Supplementation may be advised to prevent iron stores from decreasing further towards iron-deficiency anemia, where performance can be severely impacted.
What are the signs that you may be iron deficient?
Signs and symptoms of iron deficiency include tiredness, lethargy, fatigue, pallor, and shortness of breath. Ideally, reduced iron stores should be detected before they become 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 depleting further toward iron-deficiency anemia. During the early stages of iron deficiency, when stores are reduced but not exhausted, the impacts on exercise performance are subtle. However, as iron reserves become severely depleted, there is evidence that this negatively affects physical performance. Iron stores below the ideal level are likely to have a greater impact on performance in aerobic sports due to the effect of iron deficiency on oxygen transport and delivery.
How to test for iron deficiency?
Athletes should have their iron status assessed by an experienced sports physician, and a blood sample is required to test for a deficiency of the mineral.
Considerations to be made:
• Time of day – preferably in the morning.
• Hydration – athletes should be well-hydrated.
• Previous exercise – 12-24 hours of rest from exercise before the blood sample is preferred. If exercise is necessary, only low to moderate-intensity exercise should be performed in the 24 hours prior. Exercise that damages muscles should not be done in the 2-3 days prior, as it increases inflammation. Some of the proteins measured to identify iron deficiency are 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 should not show signs of illness or infection.
To diagnose iron deficiency, it is suggested that at least serum ferritin, hemoglobin concentration, and transferrin saturation be considered.
How to prevent or treat iron deficiency?
Strategy 1: Dietary Adjustments
A “food-first” approach should be adopted to prevent iron deficiency. Iron requirements are higher for athletes compared to the general population, so you should ensure you are consuming adequate amounts of iron in your diet. A nutritionist can advise you on this by conducting a dietary assessment.
However, the biggest problem in obtaining iron is not the intake of iron itself, but its bioavailability (how much of what we ingest will actually be available in the body). Iron bioavailability is generally low, and it also depends on the source of iron. There are two forms of dietary iron: heme and non-heme. Heme iron is more easily absorbed in the intestine than non-heme iron. Animal-based foods (e.g., beef, poultry, lamb, seafood, pork) contain a mixture of heme and non-heme iron, while plant-based foods (e.g., legumes, leafy greens, cereals, dried fruits, and nuts) contain almost 100% non-heme iron. The absorption of non-heme iron is about 5% compared to ~40% of heme iron. These numbers may vary depending on the study, but in general, heme iron seems to be absorbed 8 to 10 times better than non-heme iron.
In Western diets, iron obtained from heme sources constitutes about two-thirds of total iron stores, even though only one-third of dietary iron intake comes from heme iron. The presence of heme iron in a meal can increase the absorption of non-heme iron, so it is beneficial to include foods containing both heme and non-heme iron in meals.
Strategy 2: Oral Iron Supplementation
Supplementation is used after dietary adjustments if iron status does not improve or symptoms are still present (or sometimes it is used in conjunction, depending on the level of deficiency).
There are many different forms of iron that can be used in iron preparations, typically in ferrous form (e.g., sulfate, fumarate, or gluconate), but sometimes ferric forms (e.g., citrate or sulfate) are used.
Strategy 3: Intravenous (IV) Injections
To treat iron deficiency, a doctor may administer an intravenous iron injection if oral and dietary therapy does not increase serum levels or if rapid iron replenishment is needed. Additionally, it may be used if an athlete suffers from severe gastrointestinal issues due to oral iron therapy, as it bypasses the intestine (where iron is absorbed).
Once any of the above strategies have been started in an athlete with iron deficiency, iron levels should be measured every 6-8 weeks. This allows for continued treatment or modification based 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.
Hope you enjoyed, and remember to check your tests!
