Close to 70% of the body’s active — not stored — iron is in the red blood cell pigment hemoglobin where it functions to bind oxygen from the lungs and carry it to the tissues. Iron is also the active binding element of myoglobin, the pigment that makes muscle red and acts to temporarily store oxygen in muscle and deliver it to the aerobic metabolic pathways for generation of energy. Iron is an indispensable component of hundreds of other proteins and enzymes in the body.