D-Mannose is a monosaccharide hexose sugar that is part of the family of sugars in the aldohexose series. It is a sugar made by plants and is primarily found in cranberries apples peaches and raspberries among other plants. D-Mannose may help as a supplement for a variety of conditions and has been used to treat urinary tract infections. It is also considered to be a supporter of the liver and intestinal function.