What are the best common foods to clean up your gut? And help with improvement of digestion?

The gut. The intestinal track is an inherently "dirty" place. It is the body's waste disposal unit, and so is designed to not be clean. Our gut has a large number of helpful bacteria in it, without which we would have problems with digestion. So i would not be eager to "clean up" the gut. Digestion can be aided by foods with lots of fiber, and the drinking of water.