Iron for Exercise Performance

Research suggests that iron plays a meaningful role in exercise performance, particularly through its involvement in oxygen transport, energy metabolism, and the prevention of fatigue associated with iron deficiency. A Cochrane meta-analysis of 67 randomized controlled trials found that daily iron supplementation in menstruating women significantly reduced anemia prevalence and improved both maximal and submaximal exercise performance, while supporting reviews from 2014 and 2022 highlight that endurance athletes and those following plant-based diets face heightened risks of iron deficiency due to increased physiological demands and reduced dietary bioavailability. However, a 2025 double-blind randomized controlled trial in recreationally active women with iron deficiency but no anemia found that while intravenous iron improved running economy and fatigue scores, it did not significantly change peak oxygen consumption or hemoglobin mass, and individual responses were highly variable. Taken together, the evidence most consistently supports a performance benefit when iron deficiency or anemia is present, but findings are more mixed in populations without clinical anemia, and gastrointestinal side effects from supplementation remain a noted limitation across studies.