Dr. med. Konrad Werthmann (1937) is a retired general practitioner and pediatrician in Salzburg. His particular interest lies in chronic diseases, their causes, holistic diagnostics, and natural treatment and healing options. The digestive tract, with its functions as a digestive and immune organ, is at the center of Dr. Werthmann's approach to any illness and therapy. He developed the Dr. Werthmann diet, which excludes the primary allergens cow's milk and chicken eggs, based on his many years of experience. In addition to his work as a natural medicine physician, Dr. Werthmann has given numerous lectures worldwide on complementary medicine. Furthermore, he has published several books on medical topics, which have been translated into multiple languages. Throughout his long career as a physician and through his own health experiences, Dr. Werthmann has made many observations.