The important micro elements essential for normal body functions are iron, copper, iodine, fluorine, zinc, cobalt, manganese, chromium, molybdenum, selenium etc.
The total content of iron in the adult body is only 3 to 5 grams. Most of the iron is present in hemoglobin, a protein that consists of an iron-containing compound, heme, attached to a protein globin. Hemoglobin is carried in the circulation by the red blood cells. It picks up oxygen in the lungs and transports the oxygen to the tissues so that oxidation reactions can take place in the cells. From the cells the hemoglobin carries CO2 to the lungs to be exchanged.
Myoglobin is an iron-containing protein similar to hemoglobin and is present in muscle tissue. Iron is also a constituent of many enzymes that are required for oxidation of glucose and fatty acids for energy production.
Among the richest animal sources of iron are beef, liver, heart, kidneys, spleen, egg yolk and land snail. Plant sources of iron include whole wheat and its products, green vegetables, onions, coconuts and fresh fruits.
Iron requriements are influenced by the availability of iron present in foods. Iron present in cereals, legumes and green leafy vegetables is available to a lesser extent than that present in egg, meat and fish. In view of this, iron requriements of persons consuming a predominantly cereal based diet, will be greater than those consuming large quantities of meat and egg. About 10 percent of the ingested iron is only absorbed.
Infants - 10-15 mg/day
Children - 15 mg/day
Adults - 18 mg/day
During pregnancy and lactation - 40 mg/day.
Under normal conditions, very little dietary iron is absorbed which take place mainly in the stomach and the duodenum. Infants and children absorb a higher percentage of iron from food than adults. Iron deficiency in infants is due to a dietary deficiency. Iron deficient children absorb twice as much as that of normal children.
The body stores of iron are conserved very efficiently. Only lesser amounts are excreted in the urine, feces and sweat.
· Impaired iron absorption takes place in patients who have total removal of stomach or a removal of the considerable amount of the intestine.
· A diet high in phosphate causes decreased absorption due to the formation of insoluble ferric phosphate.
· Phytic acid and oxalic acid interfere with absorption.
· Vitamin C increases absorption.
· Alcohol ingestion favours iron absorption.
Insufficient iron in the diet causes iron deficiency anemia. This is common in growing children and pregnant women. Insufficiency may be brought about by blood loss during menstruation, inadequate intake of iron and hookworm infestation.