Drinking blended foods and cold-pressed juices reduce the amount of work the body has to do to digest. Thus, the nutrients are more readily absorbed into the system. With your digestion freed up, the body is able to remove old matter from the intestines and colon, like built up mucus, food, and bacteria that may be causing problems. Yuck.
A cleanse is meant to hydrate, alkalize, and rebuild with an abundance of nutrients!