About Iron deficiency
Iron has a strong oxidative, destructive impact in our body for all cells, so it is important to keep our free iron level as low as possible. At the same time, iron plays an indispensable role in numerous body functions, so its lack is also a problem.
For most pathogens, too, iron is an important nutrient, so iron supplementation and the high iron level in itself boost the proliferation of pathogens, and so it makes any chronic or acute infection even more severe. That is why in ideal case our cells store iron bound to ferritin, especially in case of infection, because for most pathogens iron is inaccessible when bound to ferritin. This is the main strategy of the body to deprive pathogens of iron, and so to protect itself against infections. Ferritin plays an important role also in the transportation of iron, as well as in regulating our free iron level. If a part of our body needs more iron (e.g. for the immune cells to produce peroxide, which it use against harmful cells/pathogens), then ferritin transports the iron there, whereas in turn, if the iron level in our blood gets too high, then ferritin stores the surplus, thus reducing it to the ideally low level.