GLOSSARY

Divalent Metal Transporter 1 (DMT1) is a membrane transporter of divalent metals involved in ferrous iron uptake into intestinal cells, not an exclusively iron-only pathway.

Vitamin C can improve meal nonheme iron absorption, while phytate and tea or coffee polyphenols can reduce it. The whole meal and body status influence the effect; a short-term absorption result is not identical to a definite long-term outcome. During deficiency correction, supplement timing and digestive tolerance are coordinated professionally rather than removing nutritious foods indiscriminately from every athlete's diet.

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.

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.