Several books on nutrition have been mentioned in the comments recently, but not everyone has access to a library that carries the books they’re interested in, or even any library at all! Dr. Weston Price wrote extensively on his travels in the 1930s to many places where he was able to observe the native culture as well as the effects of modernization on the health of younger generations. The title of his book is Nutrition and Physical Degeneration: A Comparison of Primitive and Modern Diets and Their Effects. This book is the starting place for anyone interested in the traditional foods approach to eating, and if this is all you can read, it will be enough. I thought that some of you would appreciate being able to read it for free online here .
There’s also a huge amount of information online about this approach to healthful eating, which is what I initially started with and stayed busy with for a long time. When I was finally able to get the books, I appreciated being able to systematically get the information, since it was cobbled together in my head from here and there. But there honestly hasn’t been much that I’ve read that came as something totally new after all of my online reading.
I hope this is helpful!