| Iron is a vital component of hemoglobin, which | | | | mucus), and desferrioxamine (a fungal product). |
| transports oxygen to the various tissues of the | | | | Mucosal transferrin binds iron in the lumen of the gut |
| body. Life and iron are inseparable: with the sole | | | | to transport it across the brush border of the |
| exception of lactic acid bacteria, all living organisms | | | | intestinal mucosa. Plasma transferrin transports |
| require iron as an essential element for growth and | | | | protein and binds two atoms of iron; its half-life is |
| multiplication. Iron deficiency is the most common | | | | eight days, but varies widely because iron deficiency |
| nutritional problem in the world.Free ionic iron hardly | | | | itself is a stimulus to transferrin |
| exists in the body. All the intracellular iron is either in | | | | formation.STORAGEThe total body iron is 3-5 g |
| hemoglobin or in the iron-storage protein ferritin. | | | | (54-90 mmol), the bulk of which is in hemoglobin. The |
| ABSORPTIONIron is rather unique in that nature | | | | sites of storage are the liver, spleen, and bone |
| regulates its absorption, because there is no | | | | marrow, where iron is stored as ferritin or |
| mechanism that enables excretion of excess iron1 | | | | hemosiderin.Ferritin, derived from the |
| The precise mechanisms and control of iron | | | | reticuloendothelial tissue of the liver, spleen, and bone |
| absorption are not clear.The duodenum is the main | | | | marrow, is a spherical storage iron protein which binds |
| site of iron absorption. Small intestinal iron absorption | | | | up to 4000 atoms of iron per molecule. It has 24 |
| is by a process of diffusion. The amount of iron | | | | subunits arranged in a cluster like a raspberry, and |
| absorbed is 1%-5% of the dietary iron in a normal | | | | contains 20% iron. Ferritin represents the soluble, |
| man, studied using a radioactive isotope.Because of | | | | readily mobilizable fraction of storage iron; its |
| the multiplicity of factors affecting iron absorption, it | | | | estimation, by radioimmunoassay, helps in diagnosing |
| is not possible to make a valid estimate of iron | | | | iron deficiency or overload. This estimation is less |
| absorption from a meal. The absorption varies with | | | | expensive than that of serum iron and TIBC. The |
| foods, being higher with a rice-based diet and lower | | | | normal values range from 12 to 250 micrograms per |
| with millets. Germination and baking increase | | | | litre; values less than 10 micrograms per litre denote |
| absorption, while it is reduced with tannins, tea, | | | | iron deficiency.One microgram per litre of serum is |
| tamarind, phytate and cereals. Food analysis reveals | | | | equivalent to 80 mg (1.4 mmol) storage iron. Storage |
| considerable tannin in cereals, pulses, soybeans, and | | | | iron is about 980 mg (17.5 mmol) in normal men and |
| condiments like tamarind, turmeric and chillies. | | | | 450 mg (8 mmol) in women. In iron overload, the |
| Absorption from soybean is enhanced when taken | | | | values are higher; in acute liver cell damage, too, |
| with meat or vitamins. Prolonged warming of meals | | | | release of ferritin gives abnormally high values.The |
| decreases their vitamin C content, and hence, iron | | | | structure of hemosiderin is not well understood, but it |
| absorption. The amino acid cysteine enhances iron | | | | is believed to be a degradation product of ferritin. |
| absorption from vegetables, animal foods, and iron | | | | Hemosiderin iron is not readily |
| salts.Iron in meat and liver is better absorbed than | | | | released.Desferrioxamine is a chelating agent that |
| that in eggs and leafy vegetables. With animal foods, | | | | binds iron and excretes it in the urine. The urinary |
| the mean iron absorption ranges from 7% from | | | | excretion of iron is thus easily measured, and this |
| ferritin to 22% from veal muscle, with intermediate | | | | method is utilized to estimate iron stores. Injection of |
| values of 11 % from fish and 13% from liver. Animal | | | | desferrioxamine in patients with decreased iron |
| protein in beef, pork, chicken or fish (but not egg and | | | | stores results in diminished urinary iron |
| milk) increases absorption of non-heme iron from | | | | excretion.Transferrin is a glycoprotein synthesized |
| vegetable sources. On a rice-based diet, iron | | | | mainly by the liver. It can bind two ferric iron |
| absorption increases with the addition of 40 g | | | | molecules and is responsible for the total iron-binding |
| fish.Iron absorption on a cereal diet is decreased | | | | capacity of the serum, which is 250-370 micrograms |
| because phosphate and phytates precipitate ionised | | | | per 100 ml.EXCRETIONAbsorbed iron is tenaciously |
| iron. Soya protein is a major inhibitory factor of iron | | | | bound to protein. The little excretion that occurs, as |
| absorption due to its phytate content.4Fiber in wheat | | | | with shedding of the inner lining of the digestive tract |
| and maize decreases iron absorption. Tea and coffee | | | | (desquamation of the epithelium of the mucous |
| form insoluble iron tannate that is not absorbed. | | | | membrane), cannot be correctly assessed. Iron |
| Coconut milk, used extensively in cooking in Thailand | | | | passed in stool is mostly unabsorbed dietary iron; |
| and southern India, inhibits iron absorption.Iron | | | | some iron is also -lost through the bile. Desquamation |
| absorption increases with iron-deficiency anemia, low | | | | of the skin increases iron loss with sweating in the |
| plasma iron, increased red blood cell activity in the | | | | hot, humid climate of the tropics. The urinary loss of |
| bone marrow, pancreatic deficiency, and in women. | | | | iron is negligible.IRON Loss IN WOMENA woman loses |
| Increased iron absorption occurs in normal persons | | | | additional iron during her reproductive life: (i) during |
| during menstruation, pregnancy, puberty, and after | | | | each menstrual cycle 30-60 ml of blood is lost, which |
| blood loss. Iron absorption is increased if iron body | | | | involves a monthly loss of 15-30 mg (269-537 |
| stores are depleted.Inorganic ferrous and ferric salts | | | | micromol) iron; (ii) during pregnancy the fetus, |
| are both absorbed, but ferrous iron is absorbed | | | | placenta, and loss during parturition drain the mother |
| better. There is no difference in the absorption of | | | | of over 500 mg (9 mmol) iron, which would require |
| the inexpensive ferrous sulphate and the more | | | | an increase in the daily absorption by 2 mg (36 |
| expensive slow-release iron tablets. Hemoglobin iron is | | | | micromol); and (iii) during lactation, there is an |
| absorbed intact as heme, even at neutral pH, and is | | | | additional daily loss of 1.5 mg (27 micromol) iron. |
| not affected by dietary phosphate or phytate.Gastric | | | | Owing to such losses, women--even in Western |
| acidity maintains the solubility of inorganic iron, which | | | | countries-have low iron stores.DEFICIENCY |
| aids the formation of small molecu les with ascorbic | | | | Anemia are the most common and widespread |
| acid, citrate, fructose, and amino acids. Citrate and | | | | nutrition problems. A vast majority of cases are due |
| ascorbate, being soluble, are more easily absorbed, | | | | to iron deficiency. On a global basis, 2.15 billion persons |
| while tannate (from tannic acid in tea), phytate and | | | | are anemic or iron-deficient. |
| phosphate are not so readily absorbed.Vitamin C | | | | Iron is also utilized by the brain. Iron uptake is |
| reduces ferric iron to ferrous iron which. remains | | | | maximum during rapid brain growth in the fetus 15 |
| soluble even at neutral pH and is better absorbed. | | | | Iron-deficient infants are below par in mental and |
| Even when the diet is poor in iron, vitamin C | | | | physical development. Iron intervention can reverse |
| supplement with each meal enhances iron absorption.? | | | | these development delays. |
| Vitamin C taken in divided doses with each meal will | | | | A post-cricoid web is often associated with iron |
| increase iron absorption to a greater extent than a | | | | deficiency; when followed up, some of these |
| single large dose with breakfast.Calcium inhibits iron | | | | developed cancer in that region. Lowered levels of |
| absorption. Radio-iron absorption tests in human | | | | intestinal disaccharidases occur with iron deficiency |
| volunteers show decreased absorption with | | | | anemia; this' is corrected by oral iron supplement. |
| cimetidine and antacids.BLOOD LEVELSPLASMA IRON | | | | Serum ferritin radioimmunoassay is the most reliable |
| :- Normal plasma iron level is 60-160 micrograms per | | | | test for iron-deficiency anemia. Little additional |
| 100 ml (10.74-28.6 micromol/l); the total plasma | | | | information is gained from other noninvasive |
| iron-binding capacity (TIBC) is 280-400 microgram per | | | | tests.Subodh Jain is an editor of |
| 100 ml (50.1-71.6 micromol/l), of which about one-third | | | | Vitamins-minerals-supplements.org. For more |
| is normally saturated.The iron-binding proteins are | | | | information on Iron check out |
| transferrin (siderophilin), lactoferrin (found in milk, | | | | Vitamins-minerals-supplements. |
| tears, saliva, bile, seminal secretions, and cervical | | | | |