Scientists have proved for the first time that fructose, a cheap form of sugar used in thousands of food products and soft drinks, can damage human metabolism and is fueling the obesity crisis. Fructose, a sweetener usually derived from corn, can cause dangerous growths of fat cells around vital organs and is able to trigger the early stages of diabetes and heart disease. Over 10 weeks, 16 volunteers on a controlled diet including high levels of fructose produced new fat cells around their heart, liver and other digestive organs. They also showed signs of food-processing abnormalities linked to diabetes and heart disease. Another group of volunteers on the same diet, but with glucose sugar replacing fructose, did not have these problems.