He's a medical doctor, isn't he? He's someone I've tended not to bother with ever since I read a short essay of his that tends to be bandied around the internet quite a bit but that is chock-full of dubious judgments and, what is worse, factual errors. I guess he was trying to dabble in anthropology and history and was well out of his area. Maybe I've missed some books worth looking at -- but then one can't read everything.
I know a lot of people do enjoy his stuff, though, and he does seem to be aware of the adverse impact of cereal-based diets, which is more than you can say for most doctors. If he's making diet recommendations in this book, I daresay they'll not be too far out from what people are saying in this community. And more power to his elbow if he does give good dietary advice in the book.