By highlighting the genetic differences between Japanese people and Western people, this book really, really helps dispel some dietary findings from the West (such as the caveman-style low-carb, high-fat diet that's becoming increasingly popular in Japan). For anyone who blindly believes that we should all drink olive oil, avoid all carbs (including rice), and a hodgepodge of other dietary fads, regardless of race then this is an eye-opener.
Basically, if you're Japanese or of Japanese ancestry, you should probably eat carbs (though not white rice), eat lean meat, tons of soybean products, seaweeds, and veggies and not eat too much high-fat foods.