This topic was covered on 60 Minutes yesterday. Watching the episode is recommended. Note that probiotics are not FDA approved as our system considers them "food". (This is also true for other dietary supplements). The coverage is cautionary but does not hide the interest of researchers and medical professionals. Sadly, no mention was made of the lack of efficacy of most probiotic products due to them containing no viable bacteria. Or that many others are unable to transit the stomach and its acid and thus deliver live bacteria to the colon. They mention probiotics for dogs. I purchased some Blue Buffalo kibble with probiotics for my dogs. There are separate bits that contain the probiotics, and they look, smell, and taste different from the food itself. My dogs spit them out. And so it goes. Do probiotics actually do anything?