Sugar belongs to a group of molecules called carbohydrates, which are composed of carbon, hydrogen, and oxygen and are found in fruits, vegetables, dairy products, breads, and sweets. Carbohydrates consist of a series of repeating units called monosaccharides, which include glucose, fructose, and galactose. Table sugar is made of sucrose, a disaccharide produced through the chemical reaction of glucose with fructose (Fig. 1).
Natural sugars occur most plentifully in fruits, which is what gives them their sweet and often appealing taste. Sugar is also manufactured in the form of either table sugar (sucrose) or high-fructose corn syrup (a mixture of glucose and fructose). This manufactured sugar, called added sugar, is present in many different products to improve their flavor, appearance, and texture.