D-mannose (D refers to the configuration of the carbon atom) is a monosaccharide naturally found in various plants and fruits (e.g., cranberries). It is synthesized in the body from glucose and is further involved in synthesizing glycoproteins (i.e., proteins with a carbohydrate group attached) (Alton, 1997). Pure mannose has a caloric value of four calories per gram, like other sugars. While mannose is a simple sugar absorbed in the upper gastrointestinal tract, it is absorbed slower than most sugars and is not readily converted to glycogen for storage.
Studies suggest that mannose supports urinary tract health by helping maintain normal bladder conditions (Del Popolo, 2018). More specifically, mannose helps to keep healthy mucosal surfaces in the bladder and supports normal elimination (Scaglinoe, 2021).
Alton G, Kjaergaard S, Etchison JR, Skovby F, Freeze HH. Oral ingestion of mannose elevates blood mannose levels: a first step toward a potential therapy for carbohydrate-deficient glycoprotein syndrome type I. Biochem Mol Med. 1997;60(2):127–33.
Del Popolo G, Nelli F. Recurrent bacterial symptomatic cystitis: a pilot study on a new natural option for treatment. Arch Ital Urol Androl. 2018;90(2):101–3.
Scaglione F, Musazzi UM, Minghetti P. Considerations on D-mannose Mechanism of Action and Consequent Classification of Marketed Healthcare Products. Front Pharmacol. 2021 Mar 2;12:636377.