Improvement of Immune System by Dietary Fiber! ----How Clostridium works in making intestinal environment. Why dietary fiber is good for your health? The most hardworking enterobacteria are clostridiums that feed on dietary fiber. Dietary fibers can not be dissolved by peptic juice inside intestine, but clostridiums secrete lactic acid to work on dietary fiber. It helps to maintain healthy balance of immune system in intestine. Scientists are discovering more about the role of enterobacteria as well as how food benefits human body.