IRON METABOLISM

In normal condition, the iron in our body will be in dynamic equilibrium.

    Iron is very important in the haemoglobin synthesis. Haemoglobin is very important in transferring oxygen throughout the body. Spinach is a good source of iron, and now you can connect the dots relating iron and Popeye right!

 Want some details?

    Well basically in our small intestine, the iron will be reduced from Fe3+ to Fe2+. We have studied this in Chemistry. The Fe2+ ion will be transferred in enterocytes by divalent metal transporter. It can also be transferred to the circulation system from enterocytes by FERROPORTIN1 and MTP1.

    Hepcidin is a peptide hormone where it will lead to decrease in iron absorption and release if it's expression increased. In short, the increase in hepicidin will decrease the level of iron in body or we call it iron deficiency.

    Iron is an essential elements and must be precisely regulated. On the lumen side of small intestine iron is reduced from its Ferric form to Ferrous form. The Ferrous iron is then transported in Enterocytes by Divalent Metal Transporter 1 (DMT1). In this cells, Iron can be either stored within the Enterocyte as Ferritin or it can be transferred across the basolateral membrane to the plasma by transport protein FERROPROTEIN 1 and MTP 1. Ironically, if the Ferrous wants to convert into Ferric it requires oxygen to undergoes this process by Hephaestin. 

​Transport Protein 

There are two types of transport protein that are responsible to transport iron across the Enterocytes which is;

• Divalent Metal Transporter 1 (DMT1) 

Transport iron from lumen into Enterocytes 

• FERROPORTIN 1

​Transport iron from Enterocytes to circulation

​

IRON ABSORPTION

      The absorption of iron occurs in duodenum and proximal jejunum. The rate of the absorption depends on the amount of iron molecule and iron metabolism in our body.

      In order to perform this operation, Fe3+ that is the normal state of iron ion must be converted into Fe2+ by any protein such as heme. 

      Gastric aid plays a vital role in Fe3+ oxidation as it provides low pH acid in the proximal duodenum which will allow a ferric reductase enzyme, duodenal cytochrome B in the enterocytes to convert insoluble Fe3+ into Fe2+. Once converted, The DMT1 and FERROPORTIN will aid in transfer of Fe2+ from enterocyte, which is a cell intestinal lining to the circulation.

IRON STORAGE

• Iron is stored in the liver as ferritin or hemosiderin.

• Ferritin is a protein with huge amount of Fe3+ iron where it forms a bundle of complex iron per protein molecule.

• Hemosiderin is physiologically available and it is known as complex of iron with phosphate and hydroxide forms. Usually, hemosiderin will be formed once the capacity for ferritin storage is exceeded.

Reference:

• Ems T, St Lucia K, Huecker MR. Biochemistry, Iron Absorption. [Updated 2021 Apr 26]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK448204/

• Iron Storage. (n.d.). Iron Storage. Retrieved October 2021, from https://library.med.utah.edu/NetBiochem/hi11b.htm

• Waldvogel-Abramowski, S., Waeber, G., Gassner, C., Buser, A., Frey, B. M., Favrat, B., & Tissot, J. D. (2014). Physiology of iron metabolism. Transfusion medicine and hemotherapy : offizielles Organ der Deutschen Gesellschaft fur Transfusionsmedizin und Immunhamatologie, 41(3), 213–221. https://doi.org/10.1159/000362888