What Causes Gallstones?

Progress has been made in understanding the process of gallstone formation. Researchers believe that gallstones may be caused by a combination of factors, including inherited body chemistry, body weight, gallbladder motility (movement), and perhaps diet.

Cholesterol gallstones develop when bile contains too much cholesterol and not enough bile salts. Besides a high concentration of cholesterol, two other factors seem to be important in causing gallstones. The first is how often and how well the gallbladder contracts; incomplete and infrequent emptying of the gallbladder may cause the bile to become overconcentrated and contribute to gallstone formation. The second factor is the presence of proteins in the liver and bile that either promote or inhibit cholesterol crystallization into gallstones.

Other factors also seem to play a role in causing gallstones but how is not clear. Obesity has been shown to be a major risk factor for gallstones. A large clinical study showed that being even moderately overweight increases one's risk for developing gallstones. This is probably true because obesity tends to cause excess cholesterol in bile, low bile salts, and decreased gallbladder emptying. Very low calorie, rapid weight-loss diets, and prolonged fasting, seem to also cause gallstone formation.

In addition, increased levels of the hormone estrogen as a result of pregnancy, hormone therapy, or the use of birth control pills, may increase cholesterol levels in bile and also decrease gallbladder movement, resulting in gallstone formation.

No clear relationship has been proven between diet and gallstone formation. However, low-fiber, high-cholesterol diets, and diets high in starchy foods have been suggested as contributing to gallstone formation.