Iron underpins conserved metabolic processes across all Kingdoms of life but is difficult for cells to assimilate from the environment. As such, it is the nutrient that is most competed for during host-pathogen interactions, with consequences for both.

The inflammatory response to infection incorporates a multi-faceted defence of the host’s iron resources, and success or failure of these protective mechanisms can determine the lethality of infections.

Furthermore, genetic, mechanistic, experimental and clinical data demonstrate that iron is required for innate and adaptive immune responses, and that iron-dependent biochemical processes are crucial for metabolic programming of immune cells.

Because iron deficiency is the world’s most common micronutrient disorder these findings have implications for immune responses to infections, vaccinations and immunotherapies in human populations and specific disease conditions where iron deficiency is particularly prevalent.