D-Mannose is a monosaccharide and C-2 epimer of glucose, naturally occurring in various plants, fruits, and seeds. It exists primarily in pyranose form in solution and plays roles in glycosylation and cell signaling. Used as a dietary supplement for preventing urinary tract infections by inhibiting bacterial adhesion to uroepithelial cells. It is metabolized via the Leloir pathway and has low caloric value compared to glucose. Chemically stable under normal conditions but can form Maillard reaction products with proteins at high temperatures. Soluble in water forming clear solutions; limited solubility in cold ethanol.