Fructose (also levulose or laevulose) is a simple monosaccharide found in many foods and is one of the three important dietary monosaccharides along with glucose and galactose. The organic fructose molecule was first discovered by Augustin-Pierre Dubrunfaut in 1847. Fructose is a white solid that dissolves in water – it is the most water-soluble of all the sugars. Honey, tree fruits, berries, melons, and some root vegetables contain significant amounts of molecular fructose, usually in combination with glucose, stored in the form of sucrose. About 240,000 tonnes of crystalline fructose are produced annually.

Fructose is a component of sucrose. Sucrose is a disaccharide derived from the condensation of glucose and fructose. Fructose is derived from the digestion of table sugar (sucrose).

Crystalline fructose and high-fructose corn syrup are often confused as the same product. Crystalline fructose, which is often produced from a fructose-enriched corn syrup, is indeed the monosaccharide. High-fructose corn syrup, however, refers to a family of mixtures of varying amounts of fructose and glucose.