D-Mannose is a simple sugar. Chemically, it is closely related to glucose. It is naturally occurring sugar found in cranberry and pineapple juice. When D-Mannose is ingested into the body, most of it is rapidly absorbed through the stomach and upper GI tract before reaching the intestines, emptying into the urine through the kidneys. Only a very small amount of D-manose is actually metabolized by the body.