But, if the bacteria go wrong, then digestion goes wrong. Which means the reverse is true: You can fix a lot of intestinal problems by fixing the bacteria. So for a while, science has known that isolated bacteria from human feces could be used to treat gastrointestinal disorders. But then finally somebody said, "Why not just get somebody's healthy shits and cram it all into the sick person? Then we'd know they have the right bacteria, right?"
And then they went and had a party to celebrate, because scientists are different from us.
They call it "fecal bacteriotherapy" (also known as a fecal transplant or transfusion), and we know what you're thinking: "So does this mean the donor has to come to the hospital and poop into my butt? Or do they have some kind of hose that shoves the poop into my butt?" It's neither. The human digestive tract runs one-way. If they're going to cram donor turds into you, it has to go in the other end.
This is why a lot of porn stars have incredibly healthy intestines.