Input (grade 11): First popularized in the mid 1970s by gastroenterologist Walter L. Voegtlin, this nutritional concept has been promoted and adapted by a number of authors and researchers in several books and academic journals.
Output (grade 10): Walter L. Voegtlin first made the modern Paleolithic diet popular in the 1970s. Authors and researchers recommended and changed the diet in several books and academic journals.