Iron at the crossroads of host-microbiome interactions in health and disease.

Iron is an essential dietary micronutrient for both humans and microorganisms. Disruption of iron homeostasis is closely linked, as both a cause and an effect, to the development and progression of gut microbiota dysbiosis and multiple diseases. Iron absorption in humans is impacted by diverse environmental factors, including diet, medication and microbiota-derived molecules. Accordingly, treatment outcomes for iron-associated diseases may depend on an individual patient's microbiome. Here we describe various iron acquisition strategies used by the host, commensal microorganisms and pathogens to benefit or outcompete each other in the complex gut environment. We further explore recently discovered microbial species and metabolites modulating host iron absorption, which represent potential effectors of disease and therapeutic targets. Finally, we discuss the need for mechanistic studies on iron-host-microbiome interactions that can affect disease and treatment outcomes, with the ultimate aim of supporting the development of microbiome-based personalized medicine.