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