What causes gallstones?

Dr. Lisa Ganjhu, DO

Stones form in the gallbladder like pearls form in an oyster. In this video, gastroenterologist Dr. Lisa Ganjhu explains how gallstones grow.

Ms. Ashley Koff, RD
Nutrition & Dietetics Specialist

Gallstones affect up to 20 million Americans and are twice as common among women. This can happen when there's an imbalance in the body, as gallstone formation is thought to be due to an imbalance of bile salts and minerals, dehydration, toxins, and excess cholesterol in the bile. The condition is also associated with a high-fat, low-fiber diet and pregnancy. When the delicate ratio that keeps bile in liquid form is imbalanced, crystals ("stones") form from some of those bile components. They can be a real medical problem, blocking the flow of bile from the liver and gallbladder, and sometimes obstructing the pancreas and intestines as well.

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Dr. Darria Gillespie, MD
Emergency Medicine Specialist

The gallbladder is a small organ just under your liver on the right side of your abdomen. Its function is to release bile, which breaks down fat.

Gallstones are formed by the gallbladder. While we don’t know the exact reason that they’re formed, we do know that certain people are at higher risk: people who are obese, older than 40, have diabetes, don’t get physical activity, are pregnant or have rapid weight loss or frequent fasting.

Normally, the gallbladder makes and stores bile. Then, when you eat a meal with fat, it releases that bile into the intestine. If someone has gallstones, when the gallbladder squeezes to release the bile, the gallstone blocks it—sort of like trying to squeeze out a tube of toothpaste while you’re blocking the opening. One of the older tests of gallbladder function involved drinking a really high-fat liquid to cause it to contract and release bile. This can trigger pain if you have gallstones. Over time, the stones can lead to a gallbladder infection and inflammation.

To prevent gallstones, you need to avoid the main risk factors for them. That means sticking to a healthy diet and weight, and getting exercise regularly.

If you already have gallstones but want to prevent more attacks, you should try to avoid high-fat meals (think fried foods, processed foods such as donuts and cookies, whole-milk dairy products and fatty red meat), as these are what would trigger the gallbladder to release a large amount of bile. Also avoid crash diets, as the sudden weight loss can trigger worsening stones.

Doctors are not sure about what causes gallstones. It's possible that the bile in your gallbladder may contain too much cholesterol. When that happens, your bile is unable to dissolve the cholesterol, and it turns into stones. Another possible reason is that your gallbladder does not empty frequently enough or completely. Some health conditions also can cause your liver to make too much bilirubin. A buildup of this chemical in your bile can also cause gallstones. Obesity and diets high in fat and low in fiber can also cause gallstones. Other risk factors are age (over 60), gender (women are at higher risk than men), diabetes, rapid weight loss, family history of gallstones, and taking cholesterol-lowering drugs.

Donna Hill Howes, RN
Family Practitioner

The presence of gallstones may cause more gallstones to develop. Other factors affecting gallstones, particularly cholesterol stones, include the following:

  • Gender: Women are twice as likely as men to develop gallstones. Excess estrogen from pregnancy, hormone replacement therapy, and birth control pills appears to increase cholesterol levels in bile and decrease gallbladder movement, which can lead to gallstones.
  • Family history: Gallstones often run in families, pointing to a possible genetic link.
  • Weight: A clinical study showed that being even moderately overweight increases the risk for developing gallstones. The most likely reason is that the amount of bile salts in bile is reduced, resulting in more cholesterol. Increased cholesterol reduces emptying of the gallbladder. Obesity is a major risk factor for gallstones, especially in women.
  • Diet: Diets high in fat and cholesterol and low in fiber increase the risk of gallstones due to increased cholesterol in the bile and reduced gallbladder emptying.
  • Rapid weight loss: As the body metabolizes fat during prolonged fasting and rapid weight loss—such as "crash diets"—the liver secretes extra cholesterol into bile, which can cause gallstones.
  • Age: People over the age of 60 are more likely to develop gallstones than younger people. As people age, the body tends to secrete more cholesterol into bile.
  • Ethnicity: American Indians have a genetic predisposition to secrete high levels of cholesterol in bile. In fact, they have the highest rate of gallstones. The majority of American-Indian men have gallstones by the age of 60. Among the Pima Indians of Arizona, 70 percent of women have gallstones by the age of 30.
  • Cholesterol-lowering drugs: Drugs that lower cholesterol levels in the blood actually increase the amount of cholesterol secreted into bile. In turn, the risk of gallstones increases.
  • Diabetes: People with diabetes have high levels of fatty acids called triglycerides. These fatty acids may increase the risk of gallstones.

This answer is based on source information from the National Institute of Diabetes and Digestive and Kidney Diseases.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.