Iron Toxicity: Onset and Emergency Treatment

Iron is a naturally occurring element found in great abundance throughout the universe. It is the chemical that gives red clay and the planet Mars their characteristic color; and it is found in products from paper clips to engine blocks. Iron is the essential chemical component of steel, and of course it is a mineral that is essential to life. As with all mineral nutrients, too little iron can be detrimental to one's health. Unlike many other essential minerals however, an excess of iron can result in illness and even death. Although death resulting from an iron overdose is rare, most victims of this avoidable tragedy are children aged five or under.1 This statistic, combined with the fact that the bodily absorption and metabolism of iron is affected by some very common behaviors in our society, makes the course and causes of iron toxicity pertinent knowledge for health care providers of every level.

This article addresses three topics regarding iron as a nutritional chemical: the role of iron in normal human physiology, the onset and presentation of iron toxicity, and the emergency treatment of patients suffering from iron overdose.

The Role of Iron

There are two classes of nutritional minerals: macro minerals, which the body requires in relatively large amounts, and trace minerals, which are only needed by the body in very small amounts. Iron is a trace mineral that aids in cell growth and division2. It is also the inorganic molecule upon which the oxygen-bearing proteins hemoglobin and myoglobin are formed.3

Iron is present in a variety of foods, but only a small percentage of iron that is ingested is absorbed in the gut.4 Iron that comes from animal products (called heme iron) is more easily absorbed by the body than iron found in non-animal foods. Absorption also depends on the level of iron stores in the body, as well as the presence of chemicals such as copper, cobalt, and manganese, which expedite the absorption of iron. Vitamin C is of particular benefit for those who suffer from insufficient iron stores for it greatly aids in iron absorption. Foods high in Vitamin C include citrus fruits, green peppers, broccoli, strawberries and cabbage.8 It is important to understand however, that rapid absorption of iron does not necessarily equate to its being beneficial to one's health. For example, iron that is dissolved in liquid is absorbed very easily and quickly enters the bloodstream; this "liquid" iron is also very corrosive and can damage the gastrointestinal tract.7

While some substances aid absorption of iron in the gut, others inhibit its absorption. Phytic acid is an organic molecule found in whole grains and legumes that has recently been shown to have some positive benefits for lab rats. However, phytic acid has long been known to bind proteins, starches, and minerals such as iron and slow their absorption through the lining of the small intestine10. The polyphenols present in tea or red wine also inhibit iron absorption.1,5 Calcium and caffeine both inhibit the absorption of iron. It is recommended that people who are attempting to boost their iron levels should not consume caffeine within three hours before or after the consumption of a source of iron that is intended to be of benefit to them.8

Although an iron deficiency can result in a number of undesirable effects, it is the absorption of too much iron that can result in one's requiring emergent medical treatment. Thus, the focus of the rest of this paper will be on iron toxicity.

Once excess iron has been absorbed by the gut, the body has no means of eliminating it. Because elemental iron is so damaging to tissues, the body produces specific proteins that surround free iron and keep it away from living cells. Between 70 and 80 percent of free iron is sequestered inside the spherical molecule ferritin, and the remainder is bound within the protein homosiderin.11 Ferritin and homosiderin are formed in the liver, bone marrow, and spleen. When a cell needs iron, ferretin and homosiderin attach to a transport protein called transferrin and are delivered to the cells via the blood stream.5