I listened to the audiobook version, which was narrated by the author, himself.
The trouble with this book, is it is a mixture of good advice, bad science and outright quackery. I hadn't come across "Functional Medicine" before, and if I had, I would not have chosen this book. The basic premise is that lots of problems are down to auto-immune disease caused by a "leaky gut" or a "leaky brain", which means lesions in the lining of the intenstinal wall or the blood-brain barrier and gluten. milk and sugar are all evil, especially gluten. "Molecule mimicry" causes the auto-immune system to attack things which seem bad, even though they aren't.
I am on board with why sugar can be bad. We eat far too much of it and there is evidence that fructose, in particular, causes fat to be deposited around the liver in the same way alcohol does. The book doesn't go into that, though, and doesn't cite papers or research, except in the vaguest terms. Interestingly, the author seems okay with aspartame (which my natural remedy friends aren't).
I can't remember well enough to quote the book verbatim, but it does contain some gems about how it won't work if you are too sceptical, how "his angels" had plans for him to communicate these ideas. He keeps the faith-based content relatively low, fortunately.
If you enjoyed "Wheatbelly", you'll probably enjoy this. There must be far better books out there on research into a healthy brain, though.