Ferritin Fe 5 mg by Ecological Formulas is a dietary supplement designed to supply the body with the bioavailable supply of iron it needs to produce hemoglobin for the proper transportion of oxygen throughout the body.* One of the key ingredients in Ferritin Fe 5 mg by Ecological Formulas is ferritin, the protein and natural derivative of bovine spleen responsible for enabling the body to store iron. The supply of iron provided by this supplement is the most bioavailable form possible to ensure easy absorption, without upsetting the stomach or GI tract.