Diet is unequivocally NOT the root cause for all major illness. "Many of the most common illnesses are substantially affected by diet" is a more sane claim. The

Diet is unequivocally NOT the root cause for all major illness. "Many of the most common illnesses are substantially affected by diet" is a more sane claim. There's plenty of death and disease to go around though even after you control for all the lifestyle factors. Even vegan marathon runners get cancer.