Understanding the cause of gallbladder disease will help you with preventing or treating it. More than 90% of gallstones found in people living in affluent nations are composed primarily of cholesterol. When the bile fluids in the gallbladder become over-saturated with cholesterol, precipitation of the cholesterol into solid crystals begins, and then gradually accumulate to form stones of variable sizes. A diet high in cholesterol-containing foods–red meats, poultry, fish, and dairy products–is the primary culprit for the development of the super saturated levels of cholesterol in the bile. Polyunsaturated oils (vegetable oils), too, will cause the liver to excrete larger quantities of cholesterol that pass into the fluids in the gallbladder, and thereby favor stone formation.