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.

铁对于地球上生命的出现和维持至关重要。几乎所有的生物都竞争或合作获取铁，这证明了这一基本元素对于维持代谢稳态的关键生物和生理过程的重要性。在人类和其他哺乳动物中，肠道微生物群的细菌成分与宿主之间为铁获取而进行的双向相互作用塑造了宿主和微生物群的新陈代谢。细菌功能影响宿主铁的吸收，而宿主体内铁的摄入、缺铁和铁过量会影响细菌的生物多样性、分类和功能，从而导致细菌毒力的变化。宿主-微生物串扰的这些后果影响铁的全身水平、铁在不同组织中的储存和宿主葡萄糖代谢。在宿主和微生物群之间的界面，宿主先天免疫系统和调节铁的循环可溶性因子（即铁调素、脂质运载蛋白 2 和乳铁蛋白）的改变与代谢疾病有关。事实上，患有肥胖相关代谢功能障碍和胰岛素抵抗的患者表现出铁稳态失调和肠道微生物群分布的改变。从进化的角度来看，对两种重要营养素——葡萄糖和铁——的追求可能已经推动了人类向人类生存和健康的最有效途径和基因的进化。lipocalin 2 和乳铁蛋白）与代谢疾病有关。事实上，患有肥胖相关代谢功能障碍和胰岛素抵抗的患者表现出铁稳态失调和肠道微生物群分布的改变。从进化的角度来看，对两种重要营养素——葡萄糖和铁——的追求可能已经推动了人类向人类生存和健康的最有效途径和基因的进化。lipocalin 2 和乳铁蛋白）与代谢疾病有关。事实上，患有肥胖相关代谢功能障碍和胰岛素抵抗的患者表现出铁稳态失调和肠道微生物群分布的改变。从进化的角度来看，对两种重要营养素——葡萄糖和铁——的追求可能已经推动了人类向人类生存和健康的最有效途径和基因的进化。