Iron Explained

Iron is found everywhere. It is in the soil and also the sea.
All plants and animals have found it useful and even essential. No other substance is better at binding and releasing oxygen.
The human body holds about four grams of Iron. Two thirds of that amount is held inside the Hemoglobin of the red cells. Hemoglobin is a large elaborate structure. It is a protein lattice, a vessel that holds the iron molecules tightly. Loose Iron is a free radical, a glowing ember, that can damage tissue. All life needs energy and the production of energy produces free radicals.
Another one third of the bodies iron is held inside another large protective protein vessel called Ferritin and is inside cells. This means that almost all iron in the body is stored inside either Hemoglobin or Ferritin. 
Only a tiny amount, a fraction of one percent, circulates in the blood. On lab tests this tiny fraction is called “Total Iron”. it is also carried by a protein molecule called Transferrin.
On lab tests, Iron deficiency anemia, is diagnosed by low hemoglobin and low ferritin values. That tells us total body Iron storage levels are depressed.
Total Iron circulating in the blood may or may not be low. Taking oral Iron will raise the circulating Iron but several months of treatment will be necessary to raise the Hemoglobin and Ferritin levels.