Gerson believed that cancer and other degenerative and autoimmune diseases are caused by chronic malfunctions in cell metabolism, and that they can be effectively treated by restoring proper cell functioning through a diet which is high in potassium and low in sodium. He advised a diet of fresh vegetables and fruit, with minimum cooking and ideally without animal or dairy products, fats, or sugars.
The diet is (perhaps not remarkably) similar to the change in eating patterns recommended by Dr. Joel Fuhrman.