Myths vs facts: Transferrin and Sport

Transferrin is an iron-transport protein often discussed in sports contexts. A common myth is that high transferrin levels automatically indicate good iron status. In reality, transferrin alone is not a reliable marker: transferrin saturation (TSAT), ferritin, and hepcidin provide a more complete picture. In athletes, especially endurance athletes, exercise-induced inflammation raises hepcidin, which can reduce iron availability even when ferritin appears normal. Another myth: 'more iron equals better performance.' Supplementing iron without proven deficiency does not enhance performance and may increase oxidative stress and infection risk. The fact is that individualized iron monitoring (including TSAT, ferritin, CRP) is useful to detect true deficits. Evidence is human-moderate: many observational and interventional studies exist, but results vary by sport, sex, and diet. Safety note: Iron overload (e.g., hemochromatosis) must be ruled out before supplementation.