
The author, Dr. Walker, is passionate, and after reading this I do believe that I should think about the overall health of my colon. But. He doesn't come across particularly credibly in general as a health adviser. For example, he shares an anecdote (page 66) where in his recommendation for someone suffering a heart attach is foot massage.
Now it may well be that foot massage is the answer for a heart attack. But if I keel over, I'd sure prefer to go to the Heart Hospital and get a full suite of therapy to keep me alive.
Overall, I suspect that if one carefully separates the items of real value from the hype, there's some positive content in this book.