What Does Iron Do In Our Body?
Iron is a very important part of our diet. We got to have it, we must have it, we cannot live with out. But too much of it can be a bad thing for us.
The typical American consumes about 17 mg or 0.001 ounce ofiron a day, and believe it or not about halve of that come from the 1.5 million pounds of iron added to flour and cereal products annually. In addition, we received about 600,000 pounds yearly from our vitamin pills and from supplements such as Geritol. We consume this seemingly high level of iron in an effort to keep anemiaaway and then there are others who consume it because they believe iron increases their strength. But on the flip side iron is also a poison when we consume too much of it. In the United States the sweet tasting and colorful iron pills poison about 20,000 children a year, sometimes fatally. In the 1980’s iron was the most frequent medication associated with pediatric poisoning deaths. Iron in moderately high level can even cause cirrhosis of the liver, diabetes, and congestive heart failure.
Iron Contents of Foods
Iron Content (mg/100g)
Whole Wheat Flour
White Flour (enriched)
What Happens When Iron Enters Our Body?
For starters, there are about 4.0g (0.141 ounces) of iron in an adult man weighing about 165 pounds and about 3.2g in an adult woman with the same body mass. Just about all the iron in the body, almost 99% is found in four components in our body, namely, hemoglobin, myoglobin, ferritin, and hemosiderin. About 75% of that iron is found in the first two components, the hemoglobin and myoglobin.
The first component, Hemoglobin, is the main component in our blood. This component is responsible for the characteristic red color of our blood. The main function of hemoglobin is to transport oxygen from the lungs to the tissues where the oxygen is released into the cells. The hemoglobin in a newborn is different from the hemoglobin in an adult and as the baby grows, the hemoglobin gradually changes to that of an adult. The hemoglobin is the same in all people and the genes that control the formation of hemoglobin is the same all over the world. However, there are three blood types that are determined by what is on the membrane that surrounds the hemoglobin, type A, B, and O. Occasionally, a defected gene may create an entirely different kind of hemoglobin such as the case of sickle cell anemia where the cells are not the normal, rounded, flat disc shape. Sickle cell anemia is just one of the hundreds of hemoglobin variant that are produced from defected genes and people with sickle anemia are immune to malaria because the parasite that causes malaria cannot survive in crescent shape blood cells.
The second component, Myoglobin, is similar to hemoglobin, but is a smaller molecule than hemoglobin. It is found mostly in our muscles. Muscles with a high demand for oxygen are rich in myoglobin and this is the reason why meat of animals is red. Myoglobin is in higher concentration in the muscles of some marine mammals such as whales and dolphins that sometimes their muscles appears almost black because of this high concentration of myoglobin. This gives these animals the ability to dive to extreme depths in the ocean for long periods of time. Myoglobin is the primary source of oxygen when these animals are at these extreme depths in the waters.
When our muscles are damaged myoglobin is released into the bloodstream and removed through the urine. Unfortunately this may lead to kidney damage if too much myoglobin is removed from the bloodstream this way. Also when myoglobin is found in your blood it is a sign that you may suffering from a heart attack when the test is performed with tropinin which is more specific to damaged heart muscles.
The third and fourth components, Ferritin and hemosiderin, both function as storage facilities for our iron and contain the other 25% of the iron in our bodies. These two components remove unwanted iron form our plasma and release it when it needed. If we ingest too much iron, the amount of hemosiderin increases to take up more iron and eventually the excess hemosiderin will spill over into the cells of our organs starting the process of iron poisoning.
The remaining 2% of the iron in our body serves a very important function in our body. It is critical in the final step of cellular respiration. If the transfer of electrons to an oxygen is interrupted by disabling a critical enzyme cytochrome, you will die within minutes.
How do We Keep It in Balance?
The excretion of iron from our body is very limited. A man typically loose about 1 mg of iron through his urine, feces and shredding of his skin cells. A woman during menstruation looses about 17 mg to 32 mg monthly. That means we looses about 1.5mg to 2.0 mg of iron daily. Our bodies cannot control the lost of iron because there is no mechanism for controlling this but it can maintain a balance by adjusting the amount of iron absorbed in our bodies. This balance is adjusted based on the body’s need and how much iron we are receiving from our food. This balancing mechanism works remarkably well. It would take over 10 years for the average diet to replace all the iron in an adult male if he consuming 1 mg of iron a day.
Iron poisoning occurs when a large amount of iron is ingested at once. This overwhelms the body ability to control the absorption of it. Unfortunately, this high ingestion of iron occurs in children when they accidentally swallow several iron pills at once. It only takes about two tablets with 300 mg of iron to poison a child. At least one child a month in the United States dies from ingestion of 2 grams of iron. For comparison, it would take at least 50 grams of iron to poison an adult.
Iron poisoning is commonly a chronic illness resulting from long term consumption of diets that contain high level of iron. For example, members of the Bantu tribe in South Africa consume large quantities of an alcoholic beer that is brewed in iron pots. This beer contains 750 times more iron in it than American beer. The people of this tribe suffer from a condition called Hemochromatosis, too much hemosiderin (iron storage facilities) in their organ tissues which leads to organ damage. People with a condition called Thalassemias also suffer from iron overload because they require many transfusions. Each time a Thalassemia patient receives a transfusion he will receive the iron present in that blood from the transfusion. Sometimes people suffer from an iron overload because of a defected gene that controls the absorption of iron; in this case the person’s body is absorbing too much iron. As incredible as it may sounds, some people with hemochromatosis have known to trip metal detectors at airports.
Iron is a very vital nutrient for us especially during the critical time of growth as an infant. Human milk contains little iron since an infant comes with his own reserve of iron for the first six months of his life. But as he consumes food with iron during the next two years the young child actually receives more iron than it need than any other period of his life. This happens because iron deficiency stunts growth and intelligence in a child during this critical stage of growth. Lack of enough iron in the diet of children and adolescents is the most widespread nutritional deficiency. But as an adult this metal becomes a poison especially if there is a problem where the body is absorbing too much iron. There is no other nutrient where the needs of the young is so different from those of the middle aged, and what is essential for one becomes a slow poison for the other.
© 2009 Melvin Porter
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