Absorption of Iron:
Iron is one of the most widely found elements on the surface of the earth and it is a paradox that the deficiency of it would arise in our body which contains a total of just 4-5 g of iron. Iron is not excreted from our body on a regular basis except for females in the reproductive years. The dietary iron is available in two forms:
i. The haem iron, which we get from animal sources.
ii. The non-haem iron from plant sources
The amount of iron that is absorbed from the intestines is governed by:
- The body’s need for iron during growth periods, pregnancy.
- The conditions existing in the intestinal lumen.
- The food mixture that is fed (haem containing or non-haem iron)
On average our diet provides 30-40 mg iron which is well within the requirements but the absorption of dietary iron can vary. The absorption of haem iron in the diet is 10-20%, but the non-haem iron absorption ranges only predominantly cereal based. Cereals and pulses contain phytates and these phytates combine with iron to make ferrous phytate which is an insoluble salt. Hence, the bio-availability of iron is very important.
Factors Affecting Iron Absorption:
1. In India, people consume many cereal like wheat, milets, barely, pulses, etc, which are rich in phytates which inhabit iron absorption.
2. In the acid medium of the stomach and upper duodenum, ferric iron is reduced to ferrous iron, a more soluble form that is readily absorbed. Achlorhydria observed in many elderly persons and present in pernicious anaemia reduces the absorption of iron. Similarly, the surgical removal of the portion of the stomach that produces acid will result in the lower absorption of iron.
3. The absorption of iron is meticulously regulated by the intestinal mucosa according to body needs. When there is increase in erythropoisis iron is withdrawn from the iron transferrin complex in the circulation, which lowers the transferrin saturation. This is turn, increases the absorption of iron. Thus, growing children, pregnant women and anaemic individuals. When the body needs are higher and intake is less, the body has an excellent capability to improve iron absorption.
4. Adequate levels of dietary proteins are important for optimum iron absorption and low levels are derogatory.
5. Worm infestation is a common feature among children and adults living in unhygienic and insanitary conditions. It also adversely affects the bio-availability of iron, as the worms suck away all the iron.
6. Tannins which are found in tea interfere with iron absorption.