GLOSSARY

Iron Homeostasis comprises processes regulating content, concentration and distribution; maintaining one value can involve changes in stores.

Absorbed iron exits intestinal cells through ferroportin and circulates bound to transferrin; ferritin supports cellular storage. Hepcidin limits export from intestinal cells and some stores by acting on ferroportin, changing with inflammation and iron status. Strenuous activity can transiently influence this regulation. More intake therefore does not always produce a proportional rise in uptake or iron available for physiological use.

Iron supports oxygen transport in hemoglobin, muscle function through myoglobin and electron-transfer enzymes. Inadequacy can impair exercise tolerance, but not every performance decline is iron-related. Athletes need assessment of energy intake, menstrual losses, plant-based eating, illness and training together. Raising stores without an established reason is not an independent endurance goal or a replacement for adequate recovery and training management.

Balance compares entry and exit over a defined period; homeostasis comprises processes regulating concentration and distribution. Neither means equal amounts of every mineral. Kidneys, intestine, bone and hormones contribute differently for each element. Blood values may sometimes be maintained through redistribution or stores, so one normal concentration does not necessarily summarize the entire nutritional situation or longer-term supply.

Sodium is mainly the extracellular cation and potassium mainly intracellular; chloride and other anions contribute to charge balance. Selective membranes, transporters and energy expenditure maintain these distributions. Blood concentration does not directly report muscle content. Movement between compartments may occur faster than changes in total stores and can affect a sample even without a corresponding dietary change.

Serum iron varies and alone does not diagnose stores; ferritin, hemoglobin and transferrin saturation provide complementary information with clinical context. Ferritin rises with inflammation, so a high value is not always overload. Record sampling time, recent illness and hard training. Diagnostic criteria and treatment targets differ by setting; there is no single ideal value for every athlete regardless of symptoms and methods.

Loss is not confined to sweat: urine, stool, secretions and sometimes bleeding contribute. Different elements use these routes in different proportions, so sweat volume cannot predict every mineral loss. In athletes, consider persistent changes, gastrointestinal illness, medicines and bleeding separately. Replacing one nutrient does not necessarily address the reason for its loss or establish that the rest of the mineral profile is adequate.