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