A healthy colon is a vital part of a healthy body.  The colon, along with the small and large intestines, are a major area where the nutrients in food are absorbed.  If the colon is not clean, it cannot fulfill this important task.  Not only that, the impacted fecal material that builds up in the colon and intestines releases toxins into the bloodstream.  You are in effect getting toxins instead of nutrients - not a very good trade.