There was this Cleveland dentist...

...and his name was Weston A. Price MS., D.D.S., F.A.G.D.

He was a dentist, so he got to see inside a lot of mouths. What he saw worried him - a lot. There's no point in me copying and pasting stuff that someone else has written, so read all about it at http://www.westonaprice.org/Weston-A.-Price-DDS.html

To sum-up. Mr Price travelled around the world with his wife looking inside the mouths of relatively primitive people, compared to the residents of Cleveland. What he saw impressed him - a lot. Considering that primitive people don't have access to clean water, food, medicine and other modern aids to living, they had hardly any tooth decay, gum disease or overcrowded teeth.

So he took lots of photographs, made lots of measurements and asked lots of questions. When he finished his travels, he wrote a book called Nutrition and Physical Degeneration A Comparison of Primitive and Modern Diets and Their Effects. You can read it at http://www.journeytoforever.org/farm_library/price/pricetoc.html

It's worth your while reading this book. The conclusions:-

Don't eat food that's been "buggered about with". Eat as much natural food as you can and prepare it in a way that maximises the nutrients and minimises the anti-nutrients. Don't worry about the fat in it, as fat contains the fat-soluble Vitamins A, D, E & K (but not enough D unless you live on a diet of oily fish, seals & beluga whales). For more information, see http://www.westonaprice.org/

That is all.