Iron is one of the most abundant minerals in the earth's crust, and it is required by most life forms. The Linus Pauling Institute at Oregon State University reports that iron is an essential component of hundreds of proteins and enzymes in your body. Although you must have some iron in your diet to maintain your health and well-being, excessive iron consumption -- usually from supplements -- can lead to toxicity in people who are genetically inclined to absorb extra iron.
Functions
According to the Office of Dietary Supplements, about two-thirds of your body's iron stores are found in hemoglobin, which is the red, oxygen-carrying pigment in your red blood cells. Another sizeable fraction resides in your muscles as part of myoglobin, which resembles hemoglobin. Iron is a critical component of enzymes that metabolize energy molecules, synthesize DNA and detoxify substances in your liver. Iron also supports your immune system and helps protect your tissues from oxidative damage. However, too much iron causes cellular injury.
Absorption
The absorption of iron from your intestine is determined by your body's need for iron, the type of iron present -- whether it is from animal or plant sources -- and by what other substances are consumed. Iron absorbed from your intestine is attached to transferrin, a protein produced in your liver and released into your bloodstream. Transferrin then donates iron to cells that need it, such as newly-forming red blood cells, or transfers unneeded iron to two other proteins -- ferritin and hemosiderin -- for long-term storage. Dietary iron does not usually lead to iron overload in healthy individuals.
Iron Overload
Because your body recycles iron and regulates its absorption according to your needs, additional dietary iron typically does not cause problems. According to the Linus Pauling Institute, iron overload from dietary sources is usually only seen in individuals who have hereditary conditions, such as hemochromatosis or thalassemia, that lead to excessive absorption of iron. Over time, iron overload in such persons causes damage to your liver, pancreas, nervous system, heart and joints. "The Merck Manual of Diagnosis and Therapy" reports that more than 1 million Americans are affected by hemochromatosis, and many are unaware of it.
Considerations and Precautions
Iron overload from dietary sources is rare in healthy people. However, people with hereditary conditions can absorb too much iron from their food. Toxicity and even death can result from acute overdoses of iron supplements in any individual. In fact, accidental iron overdose is the leading cause of poisoning fatalities among children under 6 years of age. Healthy men and postmenopausal women who consume a balanced diet do not need additional iron. Ask your doctor if your diet supplies adequate iron.
References
- Linus Pauling Institute at Oregon State University: Iron
- Office of Dietary Supplements: Iron
- "The Merck Manual of Diagnosis and Therapy, 18th Edition: Iron"; Mark H. Beers, M.D., Editor-in-Chief; 2006
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