How is iron absorbed into the body?

1. Absorption

Iron absorption begins with the intake of dietary iron, which can be found in both animal and plant-based sources. Once ingested, stomach acid plays a pivotal role in converting iron into a more absorbable form. This acidic environment promotes the release of iron from food and its subsequent transformation into Fe2+ (ferrous) ions.

2. Protein assistance

As the partially digested food moves into the small intestine, specifically the duodenum, the primary site of iron absorption, additional proteins come into play. One such protein, called duodenal cytochrome b (Dcytb), facilitates the reduction of Fe3+ (ferric) ions to Fe2+ ions, further enhancing their absorption capacity.

3. Transport

Following this step, a specialized iron transporter called divalent metal transporter 1 (DMT1) transports the Fe2+ ions across the cell membrane of the intestinal cells, allowing them to enter the bloodstream. Once in the bloodstream, the iron binds to transferrin, a protein that carries iron throughout the body to fulfill its various functions.

4. Control

It's important to note that iron absorption is a tightly regulated process. Hepcidin, a hormone produced by the liver, helps maintain iron balance by controlling the release of iron from intestinal cells into the bloodstream.

When iron levels are sufficient, hepcidin levels increase, limiting iron absorption and preventing iron overload. Conversely, when iron levels are low, hepcidin levels decrease, facilitating increased iron absorption to meet the body's needs.

Understanding the intricate process of iron absorption is crucial for preventing iron deficiency anemia and maintaining optimal health. Ensuring a balanced diet that includes iron-rich foods and considering factors that enhance or inhibit iron absorption can help support iron levels in the body.

References:

1. National Institute of Health. (2020). Iron. Office of Dietary Supplements. Retrieved from https://ods.od.nih.gov/factsheets/Iron-HealthProfessional/

2. Piskin, E., Cianciosi, D., Gulec, S., Tomas, M., & Capanoglu, E. (2022). Iron Absorption: Factors, Limitations, and Improvement Methods. ACS omega, 7(24), 20441–20456. https://doi.org/10.1021/acsomega.2c01833