I don’t know if everyone can see the advertisement on that link for Dr. Casey Adams probiotics book, but I’m reading his book about increased intestinal permeability (leaky gut) now, and it’s really informative. He details literally hundreds of up-to-date studies and provides a massive amount of information in a very readable way. I’ve read a number of other books on digestive, but they’re really watered-down compared to this, and more expensive.
All his book are less than £3 on the Kindle store, so I really recommend reading one if you want to know more about intestinal health. There’s a free PC reader on Amazon if you don’t have a Kindle device (I use my iPod Touch). Amazon never adds these kind of books to my recommendations list (just junk like Dukan diet rubbish), so I had to dig them out through searching.