The present inventors have found that a siderophore-iron (III) ion chelate complex is highly absorbed in the body; significantly increases the blood hemoglobin concentration, the serum iron concentration and the concentration of iron stored in the liver; and causes no adverse effects on the body. On the basis of these findings, the present inventors provide iron supplementing agents, agents for the prevention or treatment of iron defeciency anemia, food additives and food compositions, each of which contains a siderophore and iron (III) ions, preferably in the form of a chelate complex.