Tim Ferriss attempted an intense three-month protocol of prebiotics, probiotics, and dietary changes to repopulate gut diversity with limited success.

“I have had a tremendous amount of difficulty, at least as measured in common stool testing and so on, in repopulating my gut diversity. It's been extremely hard. I have consumed just about every type of pre and probiotic imaginable. I've also tweaked my diet to be more favorable for certain types of gut repopulation. It's been really tough. I did like a three-month intense protocol of all sorts of stuff. So I'd love your thoughts. I did a follow-up stool sample analysis and it was still like, "No, you're fucked."”