D-mannose is a simple sugar, much like glucose. Similar in chemical structure, these two sugars play vital roles in the extraction and utilization of energy in the body. Certain bacteria and various other microbes can also live off of glucose. In order to maintain a healthy microbial balance, modifying sugar levels helps foster an environment that is hospitable to beneficial bacteria and unfavorable to those that are unwanted. One way that D-mannose is thought to assist in the modification of a healthy urinary and digestive tract is through the adhesion of bacteria to the body. It is also possible that D-mannose binds to bacteria, and then is eliminated through urination.