In a study in 2015, researchers asked 20 fast food-loving Americans to swap diets with 20 people living in rural South Africa. What the researchers found was that the South African had “remarkable” changes in the biomarkers that indicate colon cancer risk. The good news, however, is that the American also greatly reduced these biomarkers thanks to their new rural diet. If the results of this study say anything, it’s that you should avoid processed foods as much as you can.