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Iron (Fe) is a component of hemoglobin, myoglobin, and many enzymes in the body. Heme iron, contained mainly in animal products, is absorbed much better than nonheme iron, which accounts for > 85% of iron in the average diet. However, absorption of nonheme iron is increased when it is consumed with animal protein and vitamin C.
Deficiency:
Iron deficiency, which can cause microcytic anemia (see Anemias Caused by Deficient Erythropoiesis: Iron Deficiency Anemia), is the most common nutritional deficiency in the world. It may result from inadequate iron intake, common in infants, adolescent girls, and pregnant women. It may also result from malabsorption (eg, celiac disease). Chronic bleeding may also cause iron deficiency. Chronic bleeding due to colon cancer is a common cause in middle-aged people and the elderly. When deficiency is advanced, microcytic anemia develops. Iron toxicity can damage many organs, particularly the GI tract. All people with iron deficiency require iron supplementation.
Toxicity:
Iron may accumulate in the body when a person receives iron therapy in excessive amounts or for too long, is given repeated blood transfusions, has chronic alcoholism, or takes an overdose of iron. Excess iron is toxic, causing vomiting, diarrhea, and damage to the intestine and other organs. Toxicity can also result from iron overload disease (hemochromatosis—see Iron Overload), a potentially fatal but easily treatable genetic disorder in which too much iron is absorbed. Hemochromatosis affects > 1 million Americans.
Last full review/revision November 2005
Content last modified November 2005
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