When the body needs iron, ferritin releases some iron to an iron transport protein called transferrin.
If the body does not need iron, it carried out when intestinal cells are shed and excreted in the feces.
The human body uses the three mechanisms for maintaining iron balance and preventing iron deficiency:
*continuous reutilization of iron from catabolized red blood cells
*regulations of the iron absorption from intestine
*access to ferritin, which stores and releases iron bank of the body
Iron absorption depends in part on its dietary source. Iron occurs in two forms in foods as heme iron, which found only in foods derived from the flesh of animals, such as meats, poultry and fish, and nonheme iron which is found in both plant derived and animal-derived foods. Nonheme iron is the main form of dietary iron present in cereals, vegetable, fruits, beans and peas.
Heme and non heme utilize two separate receptors on the mucosal cells.
Many dietary factors inhibit iron absorption including:
*polyphenols such as tannin derivatives
*oxalic acid
*phytic acid
*phosvitin
*divalent cations such as calcium, zinc, magnesium
By far, phytic acid appears to be the most important inhibitor of iron absorption for most populations.
Overall absorption of iron from the U.S diet is estimated at about 10% to 18%, but a person’s iron status also affects iron absorption.
Iron absorption can rise to 3 to 6 mg when the body has low iron status and can fall to 0.5 mg or less daily when iron stores are high.
Meat, fish and poultry contain not only the well-absorbed heme iron but also a peptide that promotes the absorption of nonheme iron.
Vitamin C also enhances nonheme iron absorption from foods eaten in the meal capturing the iron and keeping it in the reduced ferrous form, ready for absorption.
In addition to vitamin C, fruits and vegetables contain amounts of other organic acids that can also enhance iron absorption, and the effect of citric acid is additive to the effect of ascorbic acid.
Iron absorption
