Contents : Absorption of Iron

2. Contents : Absorption of Iron Factors affecting Fe absorption Transportation of Iron Regulation of total iron in the body Storage of Iron Daily loss of Iron

3. Absorption of Iron Iron is absorbed mainly from the small intestine, predominantly in the duodenum and upper jejunum. ( Muir and Hopfer, 1985). Picture link : http://sickle.bwh.harvard.edu/iron_absorption

4. Iron in food is in ferric form Fe+++ bound to proteins or organic acids . The ferrous form is soluble and readily absorbed

5. Factors affecting Fe absorption Promote iron absorption Acidity, Ascorbic acid and Cysteine. In iron deficiency anaemia ,Fe absorption is increased to 2 -10 times that of normal. Small peptides and amino acids favour iron uptake. Low phosphate content diet .

6. Interferes iron absorption Steatorrhea –a malabsorption syndrome Phytate and oxalate High phosphate diet Surgical removal of stomach and /or intestine

7. Iron in the mucosal cell of GIT &Plasma.

9. Ferric iron binds with a specific iron binding protein ,namely TRANSFERRIN or SIDEROPHILIN. The plasma transferrin (concentraton 250 mg/dl) can bind 400 µg of iron /dl of plasma. This is known as Total Iron Binding Capacity (TIBC ) of plasma.

10. Regulation of total iron in the body . Absorption and excretion of iron are maintained almost equally under normal physiological conditions When the iron storage is saturated in the body, it automically reduces the futher absorption of iron from the gastro intestinal tract by feedback mechanism.

11. Factors which reduce the absorption of iron: 1. Stoppage of apotransferrin formation in the liver so that the iron cannot be absorbed from the intestine. 2 . Reduction in release of iron from the transferrin , so that transferrin is completely saturated with iron and further absorption is prevented.

13. Storage of Iron Iron is stored in liver , spleen and bone marrow in the form of ferritin. In mucosal cells, ferritin is the temporary storage form of iron.

16. Hemosiderin An another iron storage protein which can hold about 35% of iron by weight. Accumulates in the body when the supply of iron is in excess of body demands.

17. Iron metabolism is unique as it operates in a close system. It is very efficiently utilized and reutilized by the body . Iron loss from the body are minimal <1mg/day through bile, sweat, hair loss, etc.

18. Iron is not excreted in to urine thus, iron differs from the vitamins or other organic and inorganic substances which are either inactivated or excreted during the course of metabolic function Hence ,iron is regarded as a one way substance.

19. Iron entry into the body is controlled at the absorption level, depending on the body needs. Periodical blood loss in menstruating women increases its requirements Increased iron demands is during pregnancy , lactation and growing children.

20. Daily loss of Iron Males: 1mg through faeces. Females high due to menstruation

21. 1 gm of haemoglobin contains 3.34mg of iron 100mlof blood contains 15gm of haemoglobin so, app 100 ml of blood contains 3.34x 15 =50mg of iron So loss of 100 ml of blood causes loss of 50 mg of iron

22. During menstrual cycle , about 50 ml of blood is loss hence there is loss of 25 mg of iron hence, female have iron content less than males.

23. During haemorrhage and blood donation If 450 ml of blood is donated 225 mg of iron is lost.

24. REFERENCES • TEXTBOOK OF BIOCHEMISTRY. 5TH EDITION. DM VASUDEVAN. • ESSENTIALS OF MEDICAL PHYSIOLOGY. 3RD EDITION. K SEMBULINGAM. • BURKET’S ORAL MEDICINE,11TH EDITION. GREENBERG ,GLICK, SHIP • PAULINE T. LIEU ET AL. THE ROLE OF IRON IN HEALTH AND DISEASE. MOLECULAR ASPECTS OF MEDICINE. 2001 FEB-APR; 22(1-2): 1-87  • J S RENNIE, D G MACDONALD, J H DAGG. IRON AND THE ORAL EPITHELIUM: A REVIEW. JOURNAL OF THE ROYAL SOCIETY OF MEDICINE. 1984 JULY; 77: 602-607