What are gallstones primarily composed of?

Gallstones are primarily composed of cholesterol, which can crystallize and form solid stones in the gallbladder. Although bile salts, calcium deposits, and proteins play roles in the composition of gallstones, they are not the main constituents.

Cholesterol gallstones form when there is too much cholesterol in the bile, and the bile cannot dissolve it, leading to the formation of crystals that become stones. Bile salts help to keep cholesterol dissolved in bile; however, an excess of cholesterol can overwhelm this mechanism. Calcium deposits can be found in some types of gallstones, but the most common form is cholesterol-based. Proteins are present in bile but do not primarily contribute to gallstone formation. Thus, the correct focus on cholesterol as the primary component differentiates it from the other substances listed.