Gut bacteria influence serum testosterone and DHT levels, and testosterone can alter gut microbiome composition.

“we know that there's a bidirectional relationship between our hormonal profile and our gut bacteria the reason why we know this is that if we look at a mouse that's a male and we take their microbiome and all of the gut bacteria inside of it we inject that into a female mouse we'll see that female mouse's testosterone in the blood increase so we know that bacteria have this influence over raising serum testosterone and serum androgen activity and then the opposite is also true serum testosterone when you inject that it changes the microbiome composition of a gut”