How human hormones regulate human microbiota: Where are we in the middle of this terra incognita?

Human organism is tightly interconnected with its microbiota on physiological and signaling levels. Microbial endocrinology as an interdisciplinary area of studying host–microbiota interactions can focus on either player: how the microbiota affects the host via synthesis of host-targeted humoral factors and how the host-derived molecules regulate the microbial community homeostasis. The present mini-review presents the authors' perspective on the impact of human hormones on the microbiota. It discusses known effects, but especially outlines existing complications in this research area, and proposes directions for future investigation.