In a gout attack, crystals of uric acid form in the joints. When the liver metabolises fructose (found in white sugar and high fructose corn syrup), uric acid is formed. Research shows that a high consumption of for example soft drinks raises the level of uric acid in the body. Therefore people with gout would theoretically be helped by avoiding sweets, fruit juices and other foods that contain large amounts of fructose. This needs to be researched scientifically.
More information: The Epidemiology of Uric Acid and Fructose , All About Gout