Dictionary:

iron

  (ī'ərn)

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1. (Symbol Fe) A silvery-white, lustrous, malleable, ductile, magnetic or magnetizable, metallic element occurring abundantly in combined forms, notably in hematite, limonite, magnetite, and taconite, and used alloyed in a wide range of important structural materials. Atomic number 26; atomic weight 55.845; melting point 1,535°C; boiling point 2,750°C; specific gravity 7.874 (at 20°C); valence 2, 3, 4, 6.
2. An implement made of iron alloy or similar metal, especially a bar heated for use in branding, curling hair, or cauterizing.
3. Great hardness or strength; firmness: a will of iron.
4. Sports. Any of a series of golf clubs having a bladelike metal head and numbered from one to nine in order of increasing loft.
5. A metal appliance with a handle and a weighted flat bottom, used when heated to press wrinkles from fabric.
6. A harpoon.
7. irons Fetters; shackles.
8. A tonic, pill, or other medication containing iron and taken as a dietary supplement.

1. Made of or containing iron: iron bars; an iron alloy.
2. Strong, healthy, and capable of great endurance: an iron constitution.
3. Inflexible; unyielding: iron resolve.
4. Holding tightly; very firm: has an iron grip.

1. 1. To press and smooth with a heated iron: iron clothes.
   2. To remove (creases) by pressing.
2. To put into irons; fetter.
3. To fit or clad with iron.

To iron clothes.

iron out

1. To settle through discussion or compromise; work out.

in irons Nautical.

1. Lying head to the wind and unable to turn either way.

1. An undertaking or project in progress: has many irons in the fire this year.

[Middle English iren, from Old English īren.]

Background

Iron is one of the most common elements on earth. Nearly every construction of man contains at least a little iron. It is also one of the oldest metals and was first fashioned into useful and ornamental objects at least 3,500 years ago.

Pure iron is a soft, grayish-white metal. Although iron is a common element, pure iron is almost never found in nature. The only pure iron known to exist naturally comes from fallen meteorites. Most iron is found in minerals formed by the combination of iron with other elements. Iron oxides are the most common. Those minerals near the surface of the earth that have the highest iron content are known as iron ores and are mined commercially.

Iron ore is converted into various types of iron through several processes. The most common process is the use of a blast furnace to produce pig iron which is about 92-94% iron and 3-5% carbon with smaller amounts of other elements. Pig iron has only limited uses, and most of this iron goes on to a steel mill where it is converted into various steel alloys by further reducing the carbon content and adding other elements such as manganese and nickel to give the steel specific properties.

History

Historians believe that the Egyptians were the first people to work with small amounts of iron, some five or six thousand years ago. The metal they used was apparently extracted from meteorites. Evidence of what is believed to be the first example of iron mining and smelting points to the ancient Hittite culture in what is now Turkey. Because iron was a far superior material for the manufacture of weapons and tools than any other known metal, its production was a closely guarded secret. However, the basic technique was simple, and the use of iron gradually spread. As useful as it was compared to other materials, iron had disadvantages. The quality of the tools made from it was highly variable, depending on the region from which the iron ore was taken and the method used to extract the iron. The chemical nature of the changes taking place during the extraction were not understood; in particular, the importance of carbon to the metal's hardness. Practices varied widely in different parts of the world. There is evidence, for example, that the Chinese were able to melt and cast iron implements very early, and that the Japanese produced amazing results with steel in small amounts, as evidenced by heirloom swords dating back centuries. Similar breakthroughs were made in the Middle East and India, but the processes never emerged into the rest of the world. For centuries the Europeans lacked methods for heating iron to the melting point at all. To produce iron, they slowly burned iron ore with wood in a clay-lined oven. The iron separated from the surrounding rock but never quite melted. Instead, it formed a crusty slag which was removed by hammering. This repeated heating and hammering process mixed oxygen with the iron oxide to produce iron, and removed the carbon from the metal. The result was nearly pure iron, easily shaped with hammers and tongs but too soft to take and keep a good edge. Because the metal was shaped, or wrought, by hammering, it came to be called wrought iron.

Tools and weapons brought back to Europe from the East were made of an iron that had been melted and cast into shape. Retaining more carbon, cast iron is harder than wrought iron and will hold a cutting edge. However, it is also more brittle than wrought iron. The European iron workers knew the Easterners had better iron, but not the processes involved in fashioning stronger iron products. Entire nations launched efforts to discover the process.

The first known European breakthrough in the production of cast iron, which led quickly to the first practical steel, did not come until 1740. In that year, Benjamin Huntsman took out a patent for the melting of material for the production of steel springs to be used in clockmaking. Over the next 20 years or so, the procedure became more widely adopted. Huntsman used a blast furnace to melt wrought iron in a clay crucible. He then added carefully measured amounts of pure charcoal to the melted metal. The resulting alloy was both strong and flexible when cast into springs. Since Huntsman was originally interested only in making better clocks, his crucible steel led directly to the development of nautical chronometers, which, in turn, made global navigation possible by allowing mariners to precisely determine their east/west position. The fact that he had also invented modern metallurgy was a side-effect which he apparently failed to notice.

Raw Materials

The raw materials used to produce pig iron in a blast furnace are iron ore, coke, sinter, and limestone. Iron ores are mainly iron oxides and include magnetite, hematite, limonite, and many other rocks. The iron content of these ores ranges from 70% down to 20% or less. Coke is a substance made by heating coal until it becomes almost pure carbon. Sinter is made of lesser grade, finely divided iron ore which, is roasted with coke and lime to remove a large amount of the impurities in the ore. Limestone occurs naturally and is a source of calcium carbonate.

Other metals are sometimes mixed with iron in the production of various forms of steel, such as chromium, nickel, manganese, molybdenum, and tungsten.

The Ore Extraction and Refining Process

Before iron ore can be used in a blast furnace, it must be extracted from the ground and partially refined to remove most of the impurities.

Extraction

• Much of the world's iron ore is extracted through open pit mining in which the surface of the ground is removed by heavy machines, often over a very large area, to expose the ore beneath. In cases where it is not economical to remove the surface, shafts are dug into the earth, with side tunnels to follow the layer of ore.

Refining

• The mined ore is crushed and sorted. The best grades of ore contain over 60% iron. Lesser grades are treated, or refined, to remove various contaminants before the ore is shipped to the blast furnace. Collectively, these refining methods are called beneficiation and include further crushing, washing with water to float sand and clay away, magnetic separation, pelletizing, and sintering. As more of the world's known supply of high iron content ore is depleted, these refining techniques have become increasingly important.
• The refined ore is then loaded on trains or ships and transported to the blast furnace site.

The Manufacturing
Process

Charging the blast furnace

• After processing, the ore is blended with other ore and goes to the blast furnace. A blast furnace is a tower-shaped structure, made of steel, and lined with refractory, or heat-resistant bricks. The mixture of raw material, or charge, enters at the top of the blast furnace. At the bottom of the furnace, very hot air is blown, or blasted, in through nozzles called tuye'res. The coke burns in the presence of the hot air. The oxygen in the air reacts with the carbon in the coke to form carbon monoxide. The carbon monoxide then reacts with the iron ore to form carbon dioxide and pure iron.

Separating the iron from the slag

• The melted iron sinks to the bottom of the furnace. The limestone combines with the rock and other impurities in the ore to form a slag which is lighter than the iron and floats on top. As the volume of the charge is reduced, more is continually added at the top of the furnace. The iron and slag are drawn off separately from the bottom of the furnace. The melted iron might go to a further alloying process, or might be cast into ingots called pigs. The slag is carried away for disposal.

Treating the gases

• The hot gases produced in the chemical reactions are drawn off at the top and routed to a gas cleaning plant where they are cleaned, or scrubbed, and sent back into the furnace; the remaining carbon monoxide, in particular, is useful to the chemical reactions going on within the furnace.

  A blast furnace normally runs day and night for several years. Eventually the brick lining begins to crumble, and the furnace is then shut down for maintenance.

Quality Control

The blast furnace operation is highly instrumented and is monitored continuously. Times and temperatures are checked and recorded. The chemical content of the iron ores received from the various mines are checked, and the ore is blended with other iron ore to achieve the desired charge. Samples are taken from each pour and checked for chemical content and mechanical properties such as strength and hardness.

Byproducts/Waste

There are a great many possible environmental effects from the iron industry. The first and most obvious is the process of open pit mining. Huge tracts of land are stripped to bare rock. Today, depleted mining sites are commonly used as landfills, then covered over and landscaped. Some of these landfills themselves become environmental problems, since in the recent past, some were used for the disposal of highly toxic substances which leached into soil and water.

The process of extracting iron from ore produces great quantities of poisonous and corrosive gases. In practice, these gases are scrubbed and recycled. Inevitably, however, some small amounts of toxic gases escape to the atmosphere.

A byproduct of iron purification is slag, which is produced in huge amounts. This material is largely inert, but must still be disposed of in landfills.

Ironmaking uses up huge amounts of coal. The coal is not used directly, but is first reduced to coke which consists of almost pure carbon. The many chemical byproducts of coking are almost all toxic, but they are also commercially useful. These products include ammonia, which is used in a vast number of products; phenol, which is used to make plastics, cutting oils, and antiseptics; cresols, which go into herbicides, pesticides, pharmaceuticals, and photographic chemicals; and toluene, which is an ingredient in many complex chemical products such as solvents and explosives.

Scrap iron and steel—in the form of old cars, appliances and even entire steel-girdered buildings—are also an environmental concern. Most of this material is recycled, however, since steel scrap is an essential resource in steelmaking. Scrap which isn't recycled eventually turns into iron oxide, or rust, and returns to the ground.

The Future

On the surface, the future of iron production—especially in the United States—appears troubled. Reserves of high-quality ore have become considerably depleted in areas where it can be economically extracted. Many long-time steel mills have closed.

However, these appearances are deceiving. New ore-enrichment techniques have made the use of lower-grade ore much more attractive, and there is a vast supply of that ore. Many steel plants have closed in recent decades, but this is largely because fewer are needed. The efficiency of blast furnaces alone has improved remarkably. At the beginning of this century, the largest blast furnace in the United States produced 644 tons of pig iron a day. It is believed that soon the possible production of a single furnace will reach 4,000 tons per day. Since many of these more modern plants have been built overseas, it has actually become more economical in some cases to ship steel across the ocean than to produce it in older U.S. plants.

Where To Learn More

Books

Lambert, Mark. Spotlight on Iron and Steel. Rourke Enterprises, 1988.

Hartley, Edward N. Iron and Steel Works of the World. International Publication, 1987.

Lewis, W. David. Iron and Steel in America. Hagley Museum, 1986.

Walker, R. D. Modern Ironmaking Methods. Gower Publication, 1986.

[Article by: Joel Simon]

A chemical element, Fe, atomic number 26, and atomic weight 55.847. Iron is the fourth most abundant element in the crust of the Earth (5%). It is a malleable, tough, silver-gray, magnetic metal. It melts at 1540°C, boils at 2800°C, and has a density of 7.86 g/cm³. The four stable, naturally occurring isotopes have masses of 54, 56, 57, and 58. The two main ores are hematite, Fe₂O₃, and limonite, Fe₂O₃ · 3H₂O. Pyrites, FeS₂, and chromite, Fe(CrO₂)₂, are mined as ores for sulfur and chromium, respectively. Iron is found in many other minerals, and it occurs in groundwaters and in the red hemoglobin of blood. See also Periodic table.

The greatest use of iron is for structural steels; cast iron and wrought iron are made in quantity, also. Magnets, dyes (inks, blueprint paper, rouge pigments), and abrasives (rouge) are among the other uses of iron and iron compounds.

There are several allotropic forms of iron. Ferrite or α-iron is stable up to 760°C (1400°F). The change of β-iron involves primarily a loss of magnetic permeability because the lattice structure (body-centered cubic) is unchanged. The allotrope called γ-iron has the cubic close-packed arrangements of atoms and is stable from 910 to 1400°C (1670 to 2600°F). Little is known about δ-iron except that it is stable above 1400°C (2600°F) and has a lattice similar to that of α-iron.

The metal is a good reducing agent and, depending on conditions, can be oxidized to the 2+, 3+, or 6+ state. In most iron compounds, the ferrous ion, iron(II), or ferric ion, iron(III), is present as a distinct unit. Ferrous compounds are usually light yellow to dark green-brown in color; the hydrated ion, Fe(H₂O)₆²⁺, which is found in many compounds and in solution, is light green. This ion has little tendency to form coordination complexes except with strong reagents such as cyanide ion, polyamines, and porphyrins. The ferric ion, because of its high charge (3+) and its small size, has a strong tendency to hold anions. The hydrated ion, Fe(H₂O)₆³⁺, which is found in solution, combines with OH⁻, F⁻, Cl⁻, CN⁻, SCN⁻, N₃⁻, C₂O₄²⁻, and other anions to form coordination complexes. See also Coordination chemistry.

An interesting aspect of iron chemistry is the array of compounds with bonds to carbon. Cementite, Fe₃C, is a component of steel. The cyanide complexes of both ferrous and ferric iron are very stable and are not strongly magnetic in contradistinction to most iron coordination complexes. The cyanide complexes form colored salts. See also Transition elements.

An essential mineral. The average adult contains 4-5 g of iron, of which 60-70% is present in the blood as haem in the circulating haemoglobin, and the remainder present in myoglobin in muscles, a variety of enzymes, and tissue stores. Iron is stored in the liver as ferritin, in other tissues as haemosiderin, and as the blood transport protein transferrin.

Iron balance: losses in faeces 0.3-0.5 mg per day, in sweat and skin cells 0.5 mg, traces in hair and urine, total loss 0.5-1.5 mg per day. Blood loss leads to a considerable loss of iron. The average diet contains 10-15 mg, of which 0.5-1.5 mg is absorbed. The haem iron of meat and fish is considerably better absorbed than the inorganic iron of vegetable foods. Reference intakes are 8.7 mg for adult men and 14.8 mg for women; women who have heavy menstrual blood losses may not be able to obtain enough from food, and supplements are necessary.

Absorption of iron is aided by vitamin C taken at the same time as iron-containing foods, and reduced by calcium, phosphate and phytic acid. Iron content of foods per 100 g: liver 6-14 mg, cereals up to 9 mg, nuts 1-5 mg, eggs 2-3 mg, meat 2-4 mg. Iron is added to flour so that it contains not less than 1.65 mg per 100 g. Fortified cereals provide 35% of the iron of British diets. Prolonged deficiency gives rise to anaemia.

Iron is essential to good health. Most iron in the body is contained in haemoglobin and myoglobin, the red pigments that carry oxygen. It also occurs as part of enzymes involved in energy production. A deficiency of iron results in anaemia, a lowering of haemoglobin concentration in the blood. The muscles and tissues are starved of vital oxygen, we feel tired and lethargic, and less inclined to exercise. Other more specific problems may include a sore tongue, cracks at the corner of the mouth, and nails that lack their usual pink flare. Heavy endurance training and bleeding (including menstrual bleeding) can increase the risk of iron deficiency and the need for iron therapy (increased iron intake by dietary adjustment and supplementation). Ten to fifteen percent of women between the ages of 13 and 45 lose more iron in menstrual bleeding than they acquire throughout the month from foods. Therefore, they probably require iron supplements to prevent iron deficiency.

The best sources of iron are meats, legumes, and watercress. Watercress and some other vegetables may have higher concentrations of iron than some meats, but iron from meat is mainly haem iron, which is easier to absorb than non-haem iron. Meat also contains a factor (not yet identified, but named MFP factor) that increases by four times the absorption of non-haem iron from other foods eaten with the meat. Cooking with traditional cast iron pans or a steel wok significantly increases the iron content of food as the surface releases fine particles, but little (if any) of this iron is absorbed. Vitamin C improves iron absorption, while tannic acid in teas, and phytic acid in many vegetables, interfere with it. (This is why you are advised not to drink large volumes of strong tea with a meal.) Large doses of other minerals (particularly calcium, copper, and zinc) in supplements may also reduce absorption. The recommended daily intake varies, but is about 8-10 mg for men and 15 mg for women of child-bearing age, increasing in physically active people.

Too much iron is toxic. It can damage the liver, heart, and pancreas, and irritate the stomach and gut, causing constipation or diarrhoea. If you take iron supplements, therefore, you should be careful not to overload your body.

noun

Something that physically confines the legs or arms. bond, chain (used in plural), fetter, handcuff (often used in plural), hobble, manacle, restraint, shackle. Archaic gyve. See free/unfree.

adjective

1. Full of vigor: able-bodied, lusty, red-blooded, robust, strapping, sturdy, vigorous, vital. See strong/weak.
2. Firmly, often unreasonably immovable in purpose or will: adamant, adamantine, brassbound, die-hard, grim, implacable, incompliant, inexorable, inflexible, intransigent, obdurate, relentless, remorseless, rigid, stubborn, unbendable, unbending, uncompliant, uncompromising, unrelenting, unyielding. Idioms: stubborn as amuleox. See resist/yield.

verb

To smooth by applying heat and pressure: mangle², press. See smooth/rough.

Idioms beginning with iron:
iron out
irons in the fire, too many

See also pump iron; strike while the iron's hot.

Definition: hard, tough; inflexible
Antonyms: flexible, soft, weak

Hardware, especially older and larger hardware of mainframe class with big metal cabinets housing relatively low-density electronics (but the term is also used of modern supercomputers). Often in the phrase big iron. Oppose silicon. See also dinosaur.

A common metallic element essential for the synthesis of hemoglobin. Its atomic number is 26 and its atomic weight is 55.85. Normal blood levels of iron range between 60 and 190 micrograms.

Description

Iron is a mineral that the human body uses to produce the red blood cells (hemoglobin) that carry oxygen throughout the body. It is also stored in myoglobin, an oxygen-carrying protein in the muscles that fuels cell growth.

General Use

Iron is abundant in red meats, vegetables, and other foods, and a well-balanced diet can usually provide an adequate supply of the mineral. But when there is insufficient iron from dietary sources, or as a result of blood loss in the body, the amount of hemoglobin in the bloodstream is reduced and oxygen cannot be efficiently transported to tissues and organs throughout the body. The resulting condition is known as iron-deficiency anemia, and is characterized by fatigue, shortness of breath, pale skin, concentration problems, dizziness, a weakened immune system, and energy loss.

Iron-deficiency anemia can be caused by a number of factors, including poor diet, heavy menstrual cycles, pregnancy, kidney disease, burns, and gastrointestinal disorders. Individuals with iron-deficiency anemia should always undergo a thorough evaluation by a physician to determine the cause.

Children two years old and under also need adequate iron in their diets to promote proper mental and physical development. Children under two who are not breastfed should eat iron-fortified formulas and cereals. Women who breastfeed need at least 15 mg of dietary or supplementary iron a day in order to pass along adequate amounts of the mineral to their child in breast milk. Parents should consult a pediatrician or other healthcare professional for guidance on iron supplementation in children.

It has been theorized that excess stored iron can lead to atherosclerosis and ischemic heart disease. Phlebotomy, or blood removal, has been used to reduce stored iron in patients with iron overload with some success. Iron chelation with drugs such as desferrioxamine (Desferal) that help patients excrete excess stores of iron can be helpful in treating iron overload caused by multiple blood transfusions.

Iron levels in the body are measured by both hemoglobin and serum ferritin blood tests.

Normal total hemoglobin levels are:

• neonates: 17-22 g/dl
• one week: 15-20 g/dl
• one month: 11-15 g/dl
• children: 11-13 g/dl
• adult males: 14-18 g/dl (12.4-14.9 g/dl after age 50)
• adult females: 12-16 g/dl (11.7-13.8 g/dl after menopause)

Normal serum ferritin levels are:

• neonates: 25-200 ng/ml
• one month: 200-600 ng/ml
• two to five months: 50-200 ng/ml
• six months to 15 years: 7-140 ng/ml
• adult males: 20-300 ng/ml
• adult females: 20-120 ng/ml

Preparations

Iron can be found in a number of dietary sources, including:

• pumpkin seeds
• dried fruits (apricots)
• lean meats (beef and liver)
• fortified cereals
• turkey (dark meat)
• green vegetables (spinach, kale, and broccoli)
• beans, peas, and lentils
• enriched and whole grain breads
• molasses
• sea vegetables (blue-green algae and kelp)

Eating iron-rich foods in conjunction with foods rich in vitamin C (such as citrus fruits) and lactic acid (sauerkraut and yogurt) can increase absorption of dietary iron. Cooking food in cast-iron pots can also add to their iron content.

The recommended dietary allowances (RDA) of iron as outlined by the United States Department of Agriculture (USDA) are as follows:

• Children 0–3: 6-10 mg/day
• children 4–10: 10 mg/day
• adolescent–adult males: 10 mg/day
• adolescent–adult females: 10-15 mg/day
• pregnant females: 30 mg/day
• breastfeeding females: 15 mg/day

A number of herbal remedies contain iron, and can be useful as a natural supplement. The juice of the herb stinging nettle (Urtica dioica) is rich in both iron and vitamin C (which is thought to promote the absorption of iron). It can be taken daily as a dietary supplement. Dandelion (Taraxacum officinale), curled dock (Rumex crispus), and parsley (Petroselinum crispum) also have high iron content, and can be prepared in tea or syrup form.

In Chinese medicine, dang gui (dong quai), or Angelica sinensis, the root of the angelica plant, is said to both stimulate the circulatory system and aid the digestive system. It can be administered as a decoction or tincture, and should be taken in conjunction with an iron-rich diet. Other Chinese remedies include foxglove root (Rehmannia glutinosa), Korean ginseng (Panax ginseng), and astragalus (Astragalus membranaceus).

Ferrum phosphoricum (iron phosphate), is used in homeopathic medicine to treat anemia. The remedy is produced by mixing iron sulfate, phosphate, and sodium acetate, which is administered in a highly diluted form to the patient. Other homeopathic remedies for anemia include Natrum muriaticum, Chinchona officinalis, Cyclamen europaeum, Ferrum metallicum, and Manganum aceticum. As with all homeopathic remedies, the type of remedy prescribed for iron deficiency depends on the individual's overall symptom picture, mood, and temperament. Patients should speak with their homeopathic professional or physician, or healthcare professional before taking any of these remedies.

Iron is also available in a number of over-the-counter supplements (i.e., ferrous fumerate, ferrous sulfate, ferrous gluconate, iron dextran). Both heme iron and nonheme iron supplements are available. Heme iron is more efficiently absorbed by the body, but non-heme iron can also be effective if used in conjunction with vitamin C and other dietary sources of heme iron. Some multivitamins also contain supplementary iron. Ingesting excessive iron can be toxic, and may have long-term negative effects. For this reason, iron supplements should be taken only under the recommendation and supervision of a doctor.

Precautions

Iron deficiency can be a sign of a more serious problem, such as internal bleeding. Anyone suffering from iron-deficiency anemia should always undergo a thorough evaluation by a healthcare professional to determine the cause.

Iron overdose in children can be fatal, and is a leading cause of poisoning in children. Children should never take supplements intended for adults, and should receive iron supplementation only under the guidance of a physician.

Individuals with chronic or acute health conditions, including kidney infection, alcoholism, liver disease, rheumatoid arthritis, asthma, heart disease, colitis, and stomach ulcer should consult a physician before taking herbal or pharmaceutical iron supplements.

If individuals taking homeopathic dilutions of ferrum phosphoricum experience worsening of their symptoms (known as a homeopathic aggravation), they should stop taking the remedy and contact their healthcare professional. A homeopathic aggravation can be an early indication that a remedy is working properly, but it can also be a sign that a different remedy is needed.

Patients diagnosed with hemochromatosis, a genetic condition in which the body absorbs too much iron and stores the excess in organs and tissues, should never take iron supplements.

Side Effects

Taking herbal or pharmaceutical iron supplements on an empty stomach may cause nausea. Iron supplementation may cause hard, dark stools, and individuals who take iron frequently experience constipation. Patients who experience dark bowel movements accompanied by stomach pains should check with their doctor, as this can also indicate bleeding in the digestive tract.

Other reported side effects include stomach cramps and chest pain. These symptoms should be evaluated by a physician if they occur.

Some iron supplements, particularly those taken in liquid form, may stain the teeth. Taking these through a straw, or with a dropper placed towards the back of the throat, may be helpful in preventing staining. Toothpaste containing baking soda and/or hydrogen peroxide can be useful in removing iron stains from teeth.

Signs of iron overdose include severe vomiting, racing heart, bloody diarrhea, stomach cramps, bluish lips and fingernails, pale skin, and weakness. If overdose is suspected, the patient should contact poison control and/or seek emergency medical attention immediately.

Interactions

Iron supplements may react with certain medications, including antacids, acetohydroxamic acid (Lithostat), dimercaprol, etidronate, fluoroquinolones. In addition, they can decrease the effectiveness of certain tetracyclines (antibiotics). Individuals taking these or any other medications should consult their healthcare professional before starting iron supplements.

Certain foods decrease the absorption of iron, including some soy-based foods, foods with large concentrations of calcium, and beverages containing caffeine and tannin (a substance found in black tea). These should not be taken within two hours of using an iron supplement. Some herbs also contain tannic acid, and should be avoided during treatment with iron supplements. These include allspice (Pimenta dioica) and bayberry (Myrica cerifera, also called wax myrtle).

Individuals considering treatment with homeopathic remedies should also consult their healthcare professional about possible interactions with certain foods, beverages, prescription medications, aromatic compounds, and other environmental elements—factors known in homeopathy as remedy antidotes—that could counteract the efficacy of treatment for iron deficiency.

Resources

Books

Medical Economics Company. PDR 2000 Physicians' Desk Reference. Montvale, NJ: Medical Economics Company, 1998.

Medical Economics Company. PDR for Herbal Medicines. Montvale, NJ: Medical Economics Company, 1998.

Ody, Penelope. The Complete Medicinal Herbal. New York: DK Publishing, 1993.

Periodicals

de Valk, B., and J.J.M. Marx. "Iron, Atherosclerosis, and Is-chemic Heart Disease." Archives of Internal Medicine 159(i14): 1542.

[Article by: Paula Ford-Martin]

Iron is a vital component of heme, the component of hemoglobin that transports oxygen in the blood. Iron deficiency is the world's most common cause of anemia (blood with low hemoglobin and red blood cell components). While some plants have modest amounts of iron (e.g., spinach), meat (red or white) has many times more iron than plants. Meat iron is also absorbed much more efficiently than plant iron. In addition to oxygen transport, iron and heme are key to normal brain development. Iron deficiency during the first six months of life can irreversibly impair cognitive development.

(SEE ALSO: Hematocrit; Hemoglobin)

Bibliography

Bridges, K. R. (2000). "Iron Deficiency." In Coun's Current Therapy, ed. R. E. Rakel. Philadelphia, PA: W. B. Saunders Company.

— KENNETH R. BRIDGES

ˈīǝrn n. 1. (irons) fetters or handcuffs.

2. informal a handgun.

in irons

1. having the feet or hands fettered.

2. (of a sailing vessel) stalled head to wind and unable to come about or tack either way.

See the Introduction, Abbreviations and Pronunciation for further details.

For more information on iron, visit Britannica.com.

The power of iron to repel evil is very well attested in English folklore, and throughout Europe—all sorts of domestic objects, and even lumps of scrap iron, were placed in homes, stables, and cowsheds as defences against withccraft and harmful fairies, or used in counterspells. Sharp ones were even more effective, and Herrick mentions ‘hooks and shears’ in stables, and knives in babies’ cradles (Hesperides (1648), nos. 890, 892). Redhot iron was a potent counterspell when milk was bewitched.

Touching iron, or merely saying ‘Touch iron!’ or ‘Cold iron!’, cancels the bad luck of breaking a taboo or seeing something ill-omened; it is not as widespread as touching wood, but some groups, such as fishermen, practise it keenly.

A picturesque 19th-century theory was that iron was first reputed magical in prehistoric times, because men using bronze or stone weapons feared those using iron swords; obviously, this is flimsy guesswork, there being no possible evidence for or against the idea.

A ductile metallic element from which pig iron and steel are made; used in its relatively crude form for making tools, castings, and so on. Also see bar iron, cast iron, malleable iron, ornamental iron, wrought iron.

A mineral element essential for health. It is a component of haemoglobin, myoglobin, cytochromes, and other chemicals involved in vital metabolic activities. Dietary sources of iron include red meat, liver, dried fruit, nuts, molasses, and legumes. The best sources contain haem iron (i.e. iron contained within haemoglobin) because it is easily absorbed from the intestine. Vitamin C improves iron absorption, but tannic acid (e.g. in tea) and phytates (e.g. in wholemeal bread) interfere with it. Excessively high iron intakes can damage the liver, heart, and pancreas. Iron deficiency may lead to anaemia, decreased oxygen transport, and feelings of lassitude. Athletes training very strenuously may require higher than normal iron intakes to avoid iron deficiency, but supplementation of iron in those who are not deficient seems to have no benefit. Taking excessive amounts of iron supplements may be dangerous. It can result in serum ferritin levels being so high that not all the iron is maintained within cells or bound to proteins. If so, the excess iron can deposit in various tissues leading to organ dysfunction.

Iron is the second most abundant mineral on earth and is an essential nutrient for nearly all organisms. Iron is necessary for many varied functions in mammals, including the synthesis of DNA, the generation of energy from macronutrients by aerobic respiration, and the transport and metabolism of oxygen. Iron is highly reactive and is potentially toxic at high levels of intake; therefore, its utilization and storage present a major challenge for biological systems. Cellular iron exists primarily in its reduced ferrous (Fe⁺²) and oxidized ferric (Fe⁺³) states, and conversion of the mineral between these states serves to catalyze many reactions. One example is Fenton's reaction, whereby hydrogen peroxide is converted to highly reactive hydroxyl radicals (.OH).