Iron

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Iron is a metal with a lustrous, metallic, greyish tinge.[1] In the Periodic Table, its symbol is Fe and its atomic number is 26. Iron is not only abundant on earth, but also in the entire universe, as it is found in the sun and in many types of stars. Iron is an important element for plant and animal life. It is the key component of hemoglobin. Pure iron is chemically reactive and it rapidly corrodes.

Uses

Among its many uses, iron is used in dietary supplements. In supplements, iron is available in two forms: ferrous and ferric. Ferrous iron salts such as ferrous fumarate, ferrous sulfate, and ferrous gluconate, are the best absorbed form of iron supplements.[2]

In the Environment

In Sewage Sludge

In the Targeted National Sewage Sludge Survey, a 2009 test of 84 samples of sewage sludge from around the U.S., the EPA found iron in every sample in concentrations ranging from 1,575 to 299,000 parts per million.[3]

Human Exposure

Humans consume iron in their diets in two forms: heme and nonheme.[4] Heme, which is derived from hemoglobin, comes from animal foods like red meat, fish, and poultry. Nonheme iron comes from plants, like lentils and beans. Whereas most dietary iron is nonheme, heme iron is absorbed better than nonheme iron. Infants absorb more iron from breastmilk than they do from infant formula.[5]

Health Effects

According to the National Institutes of Health:[6]

"Iron, one of the most abundant metals on Earth, is essential to most life forms and to normal human physiology. Iron is an integral part of many proteins and enzymes that maintain good health. In humans, iron is an essential component of proteins involved in oxygen transport. It is also essential for the regulation of cell growth and differentiation. A deficiency of iron limits oxygen delivery to cells, resulting in fatigue, poor work performance, and decreased immunity. On the other hand, excess amounts of iron can result in toxicity and even death."

"Almost two-thirds of iron in the body is found in hemoglobin, the protein in red blood cells that carries oxygen to tissues. Smaller amounts of iron are found in myoglobin, a protein that helps supply oxygen to muscle, and in enzymes that assist biochemical reactions. Iron is also found in proteins that store iron for future needs and that transport iron in blood. Iron stores are regulated by intestinal iron absorption."

Iron Deficiency

People who do not consume enough iron suffer from iron deficiency.[7] The World Health Organization considers this the number one nutritional disorder in the world, as up to 80 percent of the world's population may be iron deficient and 30 percent may have iron deficiency anemia. Iron deficiency anemia may occur from low dietary intake of iron, inadequate absorption of iron, or excessive blood loss. The groups at the greatest risk of iron deficiency are: women of childbearing age, pregnant women, preterm and low birth weight infants, older infants and toddlers, and teenage girls. Individuals with kidney failure, particularly those being treated with dialysis, are at high risk of developing iron deficiency anemia because their kidneys cannot create enough erythropoietin, a hormone needed to make red blood cells. A common problem seen in developing countries involves the way the body uses vitamin A to utilize iron.[8] When a person has a deficiency of vitamin A, they might have enough stored iron but develop an "apparent" iron deficiency all the same because they cannot use their stored iron.

Symptoms of iron deficiency anemia include feeling tired and weak, decreased work and school performance, slow cognitive and social development (in childhood), difficulty maintaining body temperature, decreased immune function/increased susceptibility to infection, and glossitis (an inflamed tongue).[9]

Iron Overload

When an individual has too much iron, they may suffer from iron overload.[10] With iron overload, excess iron is found in the blood and stored in the liver and heart. This can cause cirrhosis of the liver and heart failure. Approximately one in 250 individuals of northern European descent suffer from a genetic condition called hemochromatosis, in which the body absorbs iron very efficiently an can easily build up an excess of iron. Often hemochromatosis is not diagnosed until after iron overload has damaged an organ. For this reason, those who are not at risk of iron deficiency are not encouraged to take iron supplements.

Articles and resources

Related SourceWatch articles

References

  1. WebElements: Iron, Accessed August 31, 2010.
  2. Dietary Supplement Fact Sheet: Iron", National Institutes of Health, Accessed August 31, 2010.
  3. Targeted National Sewage Sludge Survey Report, US EPA website, Accessed August 28, 2010.
  4. Dietary Supplement Fact Sheet: Iron", National Institutes of Health, Accessed August 31, 2010.
  5. Dietary Supplement Fact Sheet: Iron", National Institutes of Health, Accessed August 31, 2010.
  6. Dietary Supplement Fact Sheet: Iron", National Institutes of Health, Accessed August 31, 2010.
  7. Dietary Supplement Fact Sheet: Iron", National Institutes of Health, Accessed August 31, 2010.
  8. Dietary Supplement Fact Sheet: Iron", National Institutes of Health, Accessed August 31, 2010.
  9. Dietary Supplement Fact Sheet: Iron", National Institutes of Health, Accessed August 31, 2010.
  10. Dietary Supplement Fact Sheet: Iron", National Institutes of Health, Accessed August 31, 2010.

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