Iron.

Iron is an essential component of hundreds of proteins and enzymes that support essential biological functions, such as oxygen transport, energy production, and DNA synthesis. Hemoglobin, myoglobin, cytochromes, and peroxidases require iron-containing heme as a prosthetic group for their biological activities. (More information)
Because the body excretes very little iron, iron metabolism is tightly regulated. In particular, the iron regulatory hormone, hepcidin, blocks dietary iron absorption, promotes cellular iron sequestration, and reduces iron bioavailability when body iron stores are sufficient to meet requirements. (More information)
Iron status can be assessed in healthy men and nonpregnant women using laboratory tests that measure serum ferritin (iron-storage protein), serum iron, total iron binding capacity, saturation of transferrin (the main iron carrier in blood), and soluble transferrin receptor. (More information)
Iron deficiency results from an inadequate supply of iron to cells following depletion of the body’s reserves. Microcytic anemia occurs when body iron stores are so low that hemoglobin synthesis and red blood cell formation are severely impaired. (More information)
Iron deficiency is the most common nutritional deficiency worldwide, affecting primarily children, women of childbearing age, pregnant women, frequent blood donors, and individuals with certain medical conditions. (More information)
Much of our iron requirement is met through recycling iron from senescent red blood cells. The recommended dietary allowance (RDA) for iron is 8 mg/day for men and postmenopausal women, 18 mg/day for premenopausal women, and 27 mg/day for pregnant women. (More information)
Iron deficiency with or without anemia in children has been associated with poor cognitive development, poor school achievement, and abnormal behavior patterns. Limited evidence suggests that iron supplementation has no effect on psychomotor development and cognitive function of anemic iron-deficient infants younger than three years but may improve attention and concentration in older children, adolescents, and women with anemia and/or iron deficiency. (More information)
Heme iron comes from hemoglobin and myoglobin in animal food sources and represents 10%-15% of total dietary iron intake of meat eaters. Yet, because it is much better absorbed than nonheme iron found in both plant and animal food sources, heme iron contributes up to 40% of total absorbed iron. (More information)
Toxic iron deposition in vital organs in patients affected by hereditary hemochromatosis has been associated with numerous chronic conditions, including liver cancer and type 2 diabetes mellitus. Increased heme iron intake and/or loss of iron homeostasis might also increase the risk of chronic disease in individuals free of genetic disorders. (More information)
Iron supplementation may cause gastrointestinal irritation, nausea, vomiting, diarrhea, or constipation, and interfere with the absorption and efficacy of certain medications, including antibiotics and drugs used to treat osteoporosis, hypothyroidism, or Parkinson’s disease symptoms. (More information)

Iron is the fourth most abundant element of Earth’s crust and one of the best studied micronutrients in nutrition science (1, 2). It is a key element in the metabolism of all living organisms. Iron exists in two biologically relevant oxidation states: the ferrous form (Fe2+) and the ferric form (Fe3+). Iron is an essential component of hundreds of proteins and enzymes supporting essential biological functions, such as oxygen transport, energy production, DNA synthesis, and cell growth and replication.