Gallstones, or choleliths, are solid masses formed from bile precipitates. These “stones” may occur in the gallbladder or the biliary tract (ducts leading from the liver to the small intestine). There are two types of gallstones: cholesterol and pigment stones. Both types have their own unique epidemiology and risk factors.
Illustration showing gallbladder and gallstone
- Cholesterol stones
Cholesterol stones are yellow-green and are primarily made of hardened cholesterol. Cholesterol stones, predominantly found in women and obese people, are associated with bile supersaturated with cholesterol. They account for 80% of gallstones and are more commonly involved in obstruction and inflammatory.
2. Pigment stones
Pigment stones may be black or brown stones. Black pigment stones are made of pure calcium bilirubinate or complexes of calcium, copper, and mucin glycoproteins. These gallstones typically form in conditions of stasis (e.g., parenteral nutrition) or excess unconjugated bilirubin (e.g., hemolysis or cirrhosis). Black pigment stones are more likely to remain in the gallbladder. Brown pigment stones are composed of calcium salts of unconjugated bilirubin with small amounts of cholesterol and protein. These stones are often located in bile ducts causing obstruction and are usually found in conditions where there is infected bile.
Who is at risk for gallstones?
- Women are more likely to develop gallstones than men. Extra estrogen can increase cholesterol levels in bile and decrease gallbladder contractions, which may cause gallstones to form. Women may have extra estrogen due to pregnancy, hormone replacement therapy, or birth control pills.
- People over age 40 are more likely to develop gallstones than younger people.
- People with a family history of gallstones have a higher risk.
Other factors that affect a person’s risk of gallstones include:
- People who are obese, especially women, have increased risk of developing gallstones. Obesity increases the amount of cholesterol in bile, which can cause stone formation.
- Rapid weight loss. As the body breaks down fat during prolonged fasting and rapid weight loss, the liver secretes extra cholesterol into bile. Rapid weight loss can also prevent the gallbladder from emptying properly. Low-calorie diets and bariatric surgery—surgery that limits the amount of food a person can eat or digest—lead to rapid weight loss and increased risk of gallstones.
- Diets high in calories and refined carbohydrates and low in fiber increase the risk of gallstones. Refined carbohydrates are grains processed to remove bran and germ, which contain nutrients and fiber. Examples of refined carbohydrates include white bread and white rice.
- Certain intestinal diseases. Diseases that affect normal absorption of nutrients, such as Crohn’s disease, are associated with gallstones.
- Metabolic syndrome, diabetes, and insulin resistance. These conditions increase the risk of gallstones. Metabolic syndrome also increases the risk of gallstone complications. Metabolic syndrome is a group of traits and medical conditions linked to being overweight or obese that puts people at risk for heart disease and type 2 diabetes.
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 liver excretes more cholesterol than your bile can dissolve, the excess cholesterol may form into crystals and eventually into stones.
- Your bile contains too much bilirubin. Bilirubin is a chemical that’s produced when your body breaks down red blood cells. Certain conditions cause the liver to make too much bilirubin, including liver cirrhosis, biliary tract infections and certain blood disorders. The excess bilirubin contributes to gallstone formation.
- Your gallbladder doesn’t empty correctly. If your gallbladder doesn’t empty completely or often enough, bile may become very concentrated, contributing to the formation of gallstones.
- Inflammations of the gallbladder (cholecystitis), the biliary tract (cholangitis), and the pancreas (biliary pancreatitis).
- Persistent pain, fever, and jaundice indicating acute cholangitis are known as Charcot’s Triad.
- Gallbladder cancer is rare but closely related to gallbladder stones, nevertheless for cancer prevention, prophylactic cholecystectomy is not recommended.
Most cases of gallstones don’t cause any symptoms. But if a gallstone blocks one of the bile ducts, it can cause sudden, severe abdominal pain, known as biliary colic.
Abdominal pain (biliary colic)
Gallstones can cause sudden, severe abdominal pain that usually lasts one to five hours (although it can sometimes last just a few minutes).
The pain can be felt:
- In the centre of your abdomen (tummy)
- Just under the ribs on your right-handside – it may spread from here to your side or shoulder blade
In a small number of people, gallstones can cause more serious problems if they obstruct the flow of bile for longer periods or move into other organs (such as the pancreas or small bowel).
If this happens, you may develop:
- A high temperature of 38C (100.4F) or above
- More persistent pain
- A rapid heartbeat
- Yellowing of the skin and whites of the eyes (jaundice)
- Itchy skin
- Chills or shivering attacks
- A loss of appetite
Prevention and management of Gallstones
- Diet may play a role in gallstones. Specific dietary factors may include:
- Although fats (particularly saturated fats found in meats, butter, and other animal products) have been associated with gallstone attacks, some studies have found a lower risk for gallstones in people who consume foods containing monounsaturated fats (found in olive and canola oils) or omega-3 fatty acids (found in canola, flaxseed, and fish oil). Fish oil may be particularly beneficial in patients with high triglyceride levels, because it improves the emptying actions of the gallbladder.
- High intake of fiber has been associated with a lower risk for gallstones.
- Studies suggest that people may be able to reduce their risk of gallstones by eating more nuts (peanuts and tree nuts, such as walnuts and almonds).
- Fruits and Vegetables. People who eat a lot of fruits and vegetables may have a lower risk of developing symptomatic gallstones that require gallbladder removal.
- High intake of sugar has been associated with an increased risk for gallstones. Diets that are high in carbohydrates (such as pasta and bread) can also increase risk, because carbohydrates are converted to sugar in the body.
- A few studies have reported a lower risk for gallstones with alcohol consumption. Even small amounts (1 ounce per day) have been found to reduce the risk of gallstones in women by 20%. Moderate intake (defined as 1 – 2 drinks a day) also appears to protect the heart.
- Research suggests that drinking coffee every day can lower the risk of gallstones.
Preventing gallstones during weight loss
- Maintaining a normal weight and avoiding rapid weight loss are the keys to reducing the risk of gallstones.
- Taking the medication ursodiol (also called ursodeoxycholic acid, or Actigall) during weight loss may reduce the risk for people who are very overweight and need to lose weight quickly.