From the Guidelines
Iron supplementation is recommended for female athletes with iron deficiency or those at risk of developing it, with a daily supplement containing 15-18 mg of elemental iron advised for prevention, and 40-60 mg daily for those with confirmed iron deficiency without anemia, and 80-100 mg daily for those with iron deficiency anemia. For female athletes, iron deficiency is a significant concern due to menstrual blood loss, reduced iron absorption from plant-based diets, gastrointestinal blood loss during intense exercise, and increased iron losses through sweat and hemolysis 1. The most recent study from 2024 suggests that monitoring iron profiles prior to altitude exposure can be useful and is an important factor in training/performance optimisation in elite athletes, with systematic large iron supplementation (210 mg daily) in female endurance athletes suggested 1. However, the optimal level of iron supplementation in athletes with clinically normal iron stores remains a subject of debate. Common supplements include ferrous sulfate, ferrous gluconate, or ferrous fumarate, and should be taken between meals with vitamin C to enhance absorption, but avoid taking with calcium, dairy, coffee, tea, or antacids which inhibit absorption 1.
Some key points to consider:
- Iron deficiency can have negative implications for aerobic performance, even without anaemia 1
- Female athletes are at higher risk of iron deficiency due to menstrual blood loss, reduced iron absorption from plant-based diets, and increased iron losses through sweat and hemolysis 1
- Regular monitoring of iron status through blood tests (hemoglobin, ferritin) is recommended, especially for endurance athletes, vegetarians/vegans, and those with heavy menstrual bleeding 1
- Treatment duration typically ranges from 3-6 months, with continued supplementation until ferritin levels normalize (>30 ng/mL) 1
- Side effects of iron supplementation may include constipation, nausea, and dark stools 1
From the FDA Drug Label
Uses Iron Supplement Purpose Iron Supplement DESCRIPTION Each tablet contains 324 mg of ferrous gluconate, equivalent to 38 mg of elemental iron, providing 211% of the U.S. recommended daily intake (RDI) of iron for adults and children 4 and older. The FDA drug label does not answer the question about iron supplement in the female athlete.
From the Research
Iron Supplementation in Female Athletes
- Iron is an essential micronutrient for female athletes, involved in oxidative metabolism and critical to exercise performance 2.
- The prevalence of iron deficiency is higher in active women, and poor iron status can be detrimental to overall health and physical performance 2, 3.
- Iron status can be assessed using indicators such as hemoglobin and serum ferritin, and clinical cut-offs for active populations remain controversial 2.
Effects of Iron Supplementation on Performance
- Oral iron supplementation in doses of 100-mg FeSO4·d (approximately 20 mg elemental iron) can improve iron status and physical performance in iron-depleted female athletes 2.
- Iron deficiency can negatively affect endurance performance by 3%-4%, but supplementation with 100 mg/day of elemental iron can improve endurance performance by 2%-20% 3.
- Maximal aerobic capacity may be improved by 6%-15% following iron supplementation, and isokinetic strength and anaerobic power performance may also be improved 3.
Types of Iron Supplementation
- Intravenous iron supplementation therapy is a safe and effective treatment for iron deficiency anemia, but is typically reserved for patients with intolerance or unresponsiveness to oral iron 4.
- Oral lactoferrin supplementation has been shown to have better effects on serum iron, ferritin, and hemoglobin concentration compared to ferrous sulfate supplementation, with fewer gastrointestinal side effects 5.
- Ferrous sulfate is a commonly used iron supplement, but can have frequent gastrointestinal side effects, and its efficacy compared to other supplements such as lactoferrin is still being studied 5, 6.