Evidence check: Ferritin Eisenmangel in the context of Sport

Ferritin is a key iron storage protein and a common marker for iron status in athletes. Low ferritin (e.g., <30 ng/mL) may indicate depleted iron stores even before anemia develops, potentially impairing endurance, recovery, and immune function. However, ferritin alone is not diagnostic: it can be falsely elevated by inflammation or lowered by overtraining. In sports, iron deficiency is multifactorial—due to increased demand, foot-strike hemolysis, sweating, or poor intake. Supplementation without confirmed deficiency is not recommended and may cause harm. Evidence for performance improvement from iron supplementation is strongest in athletes with confirmed iron deficiency (with or without anemia). For those with normal ferritin, no clear benefit exists. A full workup (CBC, transferrin saturation, CRP) is essential. Conclusion: Ferritin is a useful screening tool but must be interpreted in context. Athletes with symptoms should seek medical evaluation rather than self-supplement.