On the periodic table, iron is the main iron-containing element in hemoglobin.
Iron has atomic number 26 and the symbol Fe, taken from the Latin ferrum. In hemoglobin, iron sits in a heme group and binds oxygen reversibly, allowing red blood cells to transport oxygen from the lungs to tissues. It also helps hemoglobin carry some carbon dioxide back toward the lungs.
Iron is a transition metal and one of the most widely used structural materials after being combined with carbon to make steel. It is abundant on Earth and is thought to make up much of the planet’s core by mass.
Iron deficiency can reduce the body’s ability to make healthy hemoglobin, but iron is only one part of the molecule. Copper, zinc, and cobalt are also biologically important elements, yet they are not the central metal in hemoglobin.