Dr. Joel Wallach certainly knows his stuff. He knows the importance of minerals in diet, knows which foods to eat, and has studied long-living cultures and received his information from others who have done extensive research. What I do not like about this book is the fact the entire book is basically Wallach preaching about his supplements and his involvement in different supplement companies. His colloidal minerals are a very good, important supplement but some of his recommendations are strictly because his company happens to carry that certain product. All in all, it's a great book for someone with poor eating habits, and is in poor health. For the educated ones, you can find better material on the internet these days.. or in Robert Barefoots book "The Calcium Factor", which is the best book I have ever read in my life.