What causes gallstones?

Gall stones

Cholesterol Stones

Scientists believe cholesterol stones form when bile contains too much cholesterol, too much bilirubin, or not enough bile salts, or when the gallbladder does not empty as it should for some other reason.

Pigment Stones

The cause of pigment stones is uncertain. They tend to develop in people who have cirrhosis, biliary tract infections, and hereditary blood disorders, such as sickle cell anemia, in which too much bilirubin is formed.

Other Factors

It is believed that the mere presence of gallstones may cause more gallstones to develop. However, other factors that contribute to gallstones have been identified, especially for cholesterol stones.

• Obesity. Obesity is a major risk factor for gallstones, especially in women. A large clinical study showed that being even moderately overweight increases the risk for developing gallstones. The most likely reason is that obesity tends to reduce the amount of bile salts in bile, resulting in more cholesterol. Obesity also decreases gallbladder emptying.
  
  
• Estrogen. Excess estrogen from pregnancy, hormone replacement therapy, or birth control pills appears to increase cholesterol levels in bile and decrease gallbladder movement, both of which can lead to gallstones.
  
  
• Ethnicity. Native Americans have a genetic predisposition to secrete high levels of cholesterol in bile. In fact, they have the highest rate of gallstones in the United States. A majority of Native American men have gallstones by age 60. Among the Pima Indians of Arizona, 70 percent of women have gallstones by age 30. Mexican American men and women of all ages also have high rates of gallstones.
  
  
• Gender. Women between 20 and 60 years of age are twice as likely to develop gallstones as men.
  
  
• Age. People over age 60 are more likely to develop gallstones than younger people.
  
  
• Cholesterol-lowering drugs. Drugs that lower cholesterol levels in blood actually increase the amount of cholesterol secreted in bile. This in turn can increase the risk of gallstones.
  
  
• Diabetes. People with diabetes generally have high levels of fatty acids called triglycerides. These fatty acids increase the risk of gallstones.
  
  
• Rapid weight loss. As the body metabolizes fat during rapid weight loss, it causes the liver to secrete extra cholesterol into bile, which can cause gallstones.
  
  
• Fasting. Fasting decreases gallbladder movement, causing the bile to become overconcentrated with cholesterol, which can lead to gallstones.
  

Too much eating Fatty Foods
Gallstones are caused by too much cholesterol or calcium in the bile your liver produces, which then can crystalize. Normally if they crystalize it happens in the gallbladder, but it could still happen in the ducts that connect your liver and your stomach.
It's not clear what causes gallstones to form. Doctors think gallstones may result when:

• Your bile contains too much cholesterol. Normally, your bile contains enough chemicals to dissolve the cholesterol excreted by your liver. But if your bile contains more cholesterol than can be dissolved, the cholesterol may form into crystals and eventually into stones. Cholesterol in your bile has no relation to the levels of cholesterol in your blood.
• Your bile contains too much bilirubin. Bilirubin is a chemical that's produced when your body breaks down red blood cells. Certain conditions cause your liver to make too much bilirubin, including liver cirrhosis, biliary tract infections and certain blood disorders.
• Your gallbladder doesn't empty correctly. If your gallbladder doesn't empty completely or often enough, bile may become very concentrated and this contributes to the formation of gallstones.