This foundation follows the work of Dr Weston a price a dentist who studied the diets of traditional cultures and societies, including during Christendom. He found that they ate high fat animal based diets and they usually fermented their carbs
The foundation advocates for raw (real) milk and seems to be looking into terrain theory.
Basically it advocates for a high fat and protein diet with real food and no processed junk, it also advocates the GAPS diet for autism
However I would be weary of its stuff on homeopathy which is occult in its origins
https://www.westonaprice.org