2005-10-26 - Iron Daily Requirements and Sources
Iron is of great importance in human nutrition for healthy blood and vitality. Though it is considered as a trace element, it is responsible for oxygen transport and cellular respiration. Iron is found in the body
1) as iron porphyrins in haemoglobin, myoglobin
2) as iron enzymes in catalase, cytochrome and peroxidases.
3) as non-iron porphyrins in transferring, ferritin and haemosiderin. The iron content of the body is controlled by its absorption and not by excretion.
The total daily iron loss of an adult is less than 1 mg. During menstruation, the average loss is further 1 mg per day. It is excreted only in traces in urine, bile and faeces. The urinary loss is about 0.2 mg per day and adult. Iron loss occurs due to loss of blood in haemorrhage, loss integumental tissues, during menstrual period, and pregnance/labour. When red blood cells are broken down, the liberated iron is not excreted, but is reutilized in the formation of new red cells.
Whole blood contains about 45-50 mg of iron per 100 ml. All the red cells contain a total quantity of about 3 gm of iron. The rest of the body contains another 1-3 gm of iron. Iron is present in blood in two forms;1) as Plasma iron in the transport form-transferrin. It is in traces (0.10 mg per 100 ml) and keeps fluctuating inversely with decreased/increased rate of red cell information in aplastic/pernicious anaemias respectively.2) as Haemoglobin Iron which is about 50 mg of inorganic iron per 100 ml of blood, that accounts for 92-98% of total iron in blood.
Recommended Daily Allowance: The RDA of 1.0 mg/kg for infants, 20 mg for children, 25 mg for boys, 35 mg for girls, 24 mg for adult men, 32 mg during lactation is suggested. Normal diet provides required need. Adolescent boys/girls, and women during pregnancy and lactation need more of it. Infant lack in it as milk is deficient in Iorn, and foetal liver storage finishes in first 3 months. The body does not produce iorn; it absorbs iron from the food one eats. So the diet is a crucial factor.
Overload of iron occurs when the body can’t get rid of the mineral properly. Iron deficiency brings tiredness, but fatigue is also a common symptom to too much iron. Unchecked it can be responsible for diseases like arthritis. Too much of Iron will give you nausea, cause abdominal pain, constipation, and a damage to liver and heart. It can be toxic in excess, and can lead to cancer (due to cell damage), and heart attack, especially if your LDL level is high. This happens because iron with the help of oxygen oxidizes LDL (already in high level) to clog the arteries. Antioxidants play a role in preventing the disease. Since the need differs with age and gender, always check for iron in multivitamin tablet you take, and look for required mg of ferrous fumarate/sulphate, which is better absorbed.
Dietary Sources: All wholegrain cereals, pulses, legumes, jaggery, fish, and animal foods like egg, liver, meat etc. (except milk, butter), and vegetables like dry lotus stem, cauliflower greens, turnip greens, lentils, peas, green leafy ones and fruits like black currants, water melons, raisins, dried dates are good sources of Iron. The assimilation of iron in the body requires enzymes and gastric acids, for which iron-containing fruits which has own enzymes and acids be encouraged specially for elderly people. The bioavailability of iron in plant foods is low owing to the presence of phytates and oxalates, which interfere with iron absorption. Significant amounts of iron may be derived from cooking in iron vessels.
The iron in the diet is of two types. Heme iron present in red meat, fish and poultry is absorbed better (15-20%) and non-heme iron found in cereals, vegetables, dals, nuts and eggs (1.5%) is said to be absorbed poorly. One needs a lot of vitamin C to counter this. Just add a few drops of lime on leafy vegetables or a glass of orange juice after a meal. The surplus Heme iron when stored in body is more harmful (with higher risk of heart attacks) than a non-Heme iron.
Whole-wheat flour chapatti is better than white flour bread or rice based diet for iron nourishment. Additives in soft drinks are known to be inhibitors or iron absorption. When tea is taken with a meal, it may depress the absorption of iron by as much as 75%. The body has to use its natural resources in trying to throw out the low quality of processed, junk/fast food, cold drinks that we keep consuming. Don’t take iron along with a calcium supplement as it interferes with iron absorption. Know more about Iron Daily Requirements and its Sources
Dr John Anne
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