The car and the television set and the growing volume of office work may well have produced the most literally sedentary population human society has ever known. But at the same time, diets stuffed with the proteins and calories needed for a lumberman or a professional boxer have become prevalent.
Everywhere high meat consumption demands grain-fed animals. Meanwhile, what little grain we do eat through bread usually has little nutritional value and roughage, since these are removed when the flour is refined.
Thus the human bowel is deprived of the fiber it requires to function easily. The eating of fresh vegetables-which also give necessary fiber-has fallen off by a third in the last half century.