OK...here's what little I know...
...we have "intestinal flora." Good bacteria helps digest stuff and keep things running smoothly. Any number of factors can make the good bacteria dwindle and then bad things happen. Probiotics replenish bacteria that are known to be beneficial. I think there are other ways to go about it, too...for instance, I take soy isoflavones. I have skin and hair conditions caused by too much DHT and soy isoflavones help counter DHT without resorting to pharmaceuticals. They also prevent me from needing expen$ive skin meds. Soy isoflavones also improve intestinal flora balance (or so the bottle says), and the high dose vitamin C people say that high dose vitamin C does so, too, over time.
That's about the best I can do for you, lol.