Iron metabolism

From bacteria to humans, many molecular structures and metabolic pathways involve iron as an oxygen and/or electron carrier. However, despite its essential role for all living beings, iron is toxic by inducing the formation of free radicals. As a consequence, the human body has a fine regulation regarding the iron cycle and any unbalance can lead to diseases such as hemochromatosis and thalassemia.

The iron cycle

The human body barely absorbs iron from the outside. In fact, its loss is very low due to a constant recycling after the degradation of blood cells. The daily iron demand reaches approximatively 20 mg, which contrasts greatly compared to a total pool of 3000 to 5000 mg in the human body.

Two cycles have been described for the iron metabolism: the inner and outer cycle. The inner cycle consists of the exchange or iron between the red cells, plasma and tissue and is ensured by a soluble blood protein - transferrine. Additionally, the outer cycle is only represented by the exchange of iron between the intestins and the blood. As a consequence, the plasmatic compartment plays a key role in iron regulation and appears as the main crossroad between both cycles (figure 1).

Figure 1: The iron cycle.

Iron demand for human body

Intestinal absorption