Cyclamates are used outside the United States, but are prohibited from being used as a sweetener within the United States. The majority of sugar substitutes approved for food use are artificially synthesized compounds. However, some bulk plant-derived sugar substitutes are known, including sorbitol, xylitol and lactitol. As it is not commercially profitable to extract these products from fruits and vegetables, they are produced by catalytic hydrogenation of the appropriate reducing sugar. For example, xylose is converted to xylitol, lactose to lactitol, and glucose to sorbitol.