Iron (Symbol= Fe, Latin ferrum-A metallic element. Iron can be found in most soils and in various minerals. Iron is required as a component for haemoglobin in erythrocytes (red blood cells, RBC's). Iron in haemoglobin binds oxygen. Without iron, oxygen cannot be "loaded" into the red blood cell for transportation throughout the body. Therefore, iron is an essential element for metabolism. Iron is also a necessary element for cytochromes and other enzymes. Iron can also be stored in the body in the form of ferritin and hemosiderin. The various iron containing enzymes and serum iron only represent about 1% fo the total body iron. The average adult male probably contains in the order of 5 grams (sixth of an ounce, 1/96th of a pound :oP ) of total body iron.

COmpounds of iron are astringent and styptic. Astingent comes from the latin stringens "to bind". Astrigents applied topically, cause local contraction. Styptic from Greek styptikos means astringent, stopping haemorrhaging or bleeding. Many of us may remember "styptic" pencils, those "lipstic-shaped" object that were rubbed on the skin over a shaving cut. This instantly stopped the bleeding.

RDA of Iron

The RDA for iron is not fully established. Although iron is required amounts vary for individuals. For example, women lose around 30 ml of blood during menstruation. This equates to an estimated loss of only 12 mg of iron. This total loss equates to about one days intake, so it;s not a substantial loss, and the female can make up for this loss by increasing the iron intake by a half a milligram (0.5mg). Of course, heavy periods can cause greater blood loss. Additionally, injuries such as haemorrhage can also lead to iron loss. Iron is also lost through other mechanisms such as desquamation, or loss of dead skin through shedding, wear and tear, etc. Iron contained in dead skin, simply falls off the body, since the dead cells shed. Small amounts of iron are also lost through faeces, urine and sweat.

The average diet provides around 12 mg of iron per day. Foods that contain high amounts of iron are blood sausage ("black pudding"), liver, treacle, millets and wheat flour. Iron is also found in high concentrations in certain vegetables. Amounts vary considerably, even in the same vegetables, due to the type of soil that they were grown in. Some soils have higher iron contents and thus, plants will be able to absorb more iron through their roots.

Iron present in the haem (heme) form is best absorbed. The haem form means that an atom of the element iron is in the form Fe²⁺. Fe²⁺ form is called the "ferrous" form of iron. This means that two electrons are missing, and since electrons are negatively charged, two missing gives the iron atom a net positive charge. It isn't essential that you learn this amount of detail. The main point to be aware of is that most animal derived foods are in the haem (Fe²⁺) form. This form of iron is absorbed very well compared to inorganic iron from vegetable foods. The iron in vegetables for example, is in the form Fe³⁺. This called the "ferric" form of iron. The ferric form of iron in vegetables is bound to proteins, phosphates, oxalates, and phytates. This demonstrates why iron deficiencies occur in populations who consume cereals as the main portion of their diet, although there are high amounts of iron in cereals. Cereals contain high amounts of iron on average (depending on soil also). But because the iron is bound to phytate, absorption in the gut is poor. Adding other vegetables or supplements to the diet obviously help. Tannins in tea may also inhibit the absorption of iron in the gut.

Iron absorption from inorganic sources can be increased with vitamin C (ascorbic acid) Ascorbic acid changes iron from the ferric state (Fe³⁺) to the ferrous state (Fe²⁺), enabling it to be more easily absorbed in the gut. The hydrochloric acid (HCL) produced by the parietal cells of the stomach also convert iron from the ferric form to the ferrous form.

Deficiency and Toxicity of Iron

Deficiency of iron results in anaemia (anemia). Anemia is High doses of iron as iron salts are toxic and have caused many deaths in chidren from accidental poisoning. Toxic doses of iron initially cause nausea, vomiting and diarrhoea. This is followed by gastrointestinal bleeding, hypotension, and liver damage. This is an emergency in which a hospital will treat with oral desferrioxamine, which chelates iron and prevents absorption ahd intravenous (IV) deferrioxamine, which chelates the already absorbed iron.