Here is some info..hope it helps you,
Disease of the gallbladder
Normally the gallbladder rarely causes problems in childhood or early adult life. However, from middle age onward, there is an increased risk of developing gallstones. Gallstones occur when the bile becomes chemically unbalanced and forms crystals. Over time, these crystals become hardened particles that eventually grow into stones. Gallstones can vary in size, shape, number and type. For example, they may contain substances such as cholesterol, pigment, calcium or a mixture of substances. Some people may only have one gallstone, while others may develop hundreds. Every year thousands of people develop gallstones, but only 20 percent of these people will develop symptoms. The remainder carry