D-mannose is a simple sugar (monosaccharide) that is structurally related to glucose. It naturally occurs in small amounts in fruits such as cranberries, apples and oranges. In supplement form, it is used as a pure substance, separate from other fruit components.

The D-mannose in this product is synthetically produced or isolated from natural sugars and then purified. It is not directly extracted from fruit, but is chemically identical to the natural form found in plants.

Although they are chemically related, D-mannose and glucose differ in structure and processing. D-mannose is not used as an energy source in the same way, and follows a different pathway in the diet. Table sugar (sucrose) is also a disaccharide, while D-mannose is a monosaccharide.