Body iron distribution. The average adult human contains 3–5 g iron, most of which is incorporated in hemoglobin within red blood cells. Skeletal muscle myoglobin also contains iron. Hemoglobin- and myoglobin-derived iron plays a key role in tissue oxygenation. Thus, these are referred to as functional pools. Approximately 20–30% of iron in the body is stored in the form of ferritin and hemosiderin in hepatocytes and tissue macrophages (storage pool). While only about 3 mg of iron is bound to circulating transferrin (transport pool), the plasma transferrin pool is highly dynamic, transferring about 20 mg of (mostly recycled) iron each day to the bone marrow, which produces about 200 billion new erythrocytes daily (erythropoietic pool), and other tissues (all cells require iron, for example as part of intracellular respiratory enzymes). Healthy people absorb 1–2 mg of iron per day which compensates for iron loss. Learn more here.
