Probiotics aren’t a silver bullet, but they can play a supportive role. Many studies have shown benefits, like this one I was just reading, which concludes:
1) Fungal colonization delays process of ulcer and inflammation healing of GI tract mucosa. That effect was attenuated by probiotic therapy.
2) Probiotic therapy seems to be effective in treatment of fungal colonization of GI tract.
3) Lactobacillus acidophilus therapy shortens the duration of fungal colonization of mucosa (enhanced Candida clearance is associated with IL-4, INF-gamma response).
I’d question the long-term impact of having non-indigenous species permanently colonise the gut without further research. I think the term “good bacteria” is a bit misleading too, because they’re all out for themselves. More isn’t always better. What you want is the gut flora you had before any of your problems, assuming it was ever in good shape (some people are disadvantaged from birth).
Like Jorge said, probiotics can set you back a lot of money and don’t necessarily guarantee anything. They’re also the worst when it comes to reliable CFU counts. Fermented foods are an affordable and reliable option. I’ve been wondering about lactate content lately though. Nothing seems straightforward any more…