Fructose is a simple sugar (monosaccharide) found in many foods. It is also one of the three most important blood sugars, the other two are glucose and galactose. Honey; tree fruits; berries; melons; and some root vegetables, such as beets, sweet potatoes, parsnips and onions, contain fructose, usually with sucrose and glucose. Processed foods also contain fructose due to how sweet it is.