Physics

Carbohydrate metabolism

Gut flora

Biology

Microbiology

Optics

Host (biology)

Crosstalk

Immunology

Ferroportin

Hepcidin

Inflammation

Dysbiosis

Iron homeostasis

Metabolism

Cell biology

Genetics

Biochemistry

Homeostasis

Nature Reviews Endocrinology

Iron is critical for the appearance and maintenance of life on Earth. Almost all organisms compete or cooperate for iron acquisition, demonstrating the importance of this essential element for the biological and physiological processes that are key for the preservation of metabolic homeostasis. In humans and other mammals, the bidirectional interactions between the bacterial component of the gut microbiota and the host for iron acquisition shape both host and microbiota metabolism. Bacterial functions influence host iron absorption, whereas the intake of iron, iron deficiency and iron excess in the host affect bacterial biodiversity, taxonomy and function, resulting in changes in bacterial virulence. These consequences of the host–microbial crosstalk affect systemic levels of iron, its storage in different tissues and host glucose metabolism. At the interface between the host and the microbiota, alterations in the host innate immune system and in circulating soluble factors that regulate iron (that is, hepcidin, lipocalin 2 and lactoferrin) are associated with metabolic disease. In fact, patients with obesity-associated metabolic dysfunction and insulin resistance exhibit dysregulation in iron homeostasis and alterations in their gut microbiota profile. From an evolutionary point of view, the pursuit of two important nutrients — glucose and iron — has probably driven human evolution towards the most efficient pathways and genes for human survival and health. Patients with obesity-associated metabolic dysfunction exhibit dysregulation in iron homeostasis and alterations in gut microbiota composition and functionality. This Review discusses the bidirectional relationships between the host and the microbiota in the acquisition of elemental iron and the implications for glucose metabolism.

The role of iron in host–microbiota crosstalk and its effects on systemic glucose metabolism