What ultimately causes gallstone formation is still unclear. However, researchers have discovered instances that might prompt gallstone development. In particular, an imbalance in the chemical composition of bile, a liquid produced by the liver to help with digestion, is said to be predominantly responsible for gallstones, especially when:1,2
• Bile contains too much cholesterol: Typically, bile has enough chemicals to dissolve the cholesterol released by the liver. However, if the liver excretes more cholesterol than what bile can dissolve, excess cholesterol can turn into crystals, and into what's known as gallstones.
• Bile contains too much bilirubin: Bilirubin is a chemical that's produced when the body breaks down red blood cells. If you have conditions like liver cirrhosis, biliary tract infections or certain blood-related conditions, this can prompt the liver to increase bilirubin production. The excess bilirubin in your system can lead to gallstone formation.
Aside from these two bile-related causes, gallstones can form if a person’s gallbladder does not empty correctly. Failure of the gallbladder to empty completely or often enough can cause bile to become very concentrated and lead to gallstone formation.3
Risk Factors for Gallstones
✓ Gender (females are more prone to have gallstones6)
✓ Age (particularly being 40 years old or above)
✓ Race (Native Americans or Mexican-Americans)
✓ Being overweight or obese
✓ Being sedentary
✓ Being pregnant
✓Eating a high-fat or high-cholesterol diet
✓Eating a low-fiber diet
✓ Losing weight very quickly
✓ Having diabetes
✓ Having a family history of gallstones
✓ Having a disease that affects the flow of bile such as cirrhosis (scarring of the liver), primary sclerosing cholangitis or obstetric cholestasis
✓ Having Crohn's disease or irritable bowel syndrome (IBS)
✓ Taking estrogen-containing medicines like oral contraceptives or hormone therapy drugs
✓ Taking an antibiotic called ceftriaxone
What Are the Types of Gallstones That Can Form in the Body?
There are two types of gallstones that can form in your gallbladder. These are:7
• Cholesterol gallstones: These stones are usually yellow, and are the most common type of gallstone, responsible for around 80 percent of gallstones among individuals in Europe and the Americas.8 Although they are mainly composed of undissolved cholesterol, these stones may also contain other components.
• Pigment gallstones: These dark brown or black stones often develop as a result of having too much bilirubin in your bile. Aside from high amounts of bilirubin, pigment gallstones may also consist of phosphate, carbonate and other anions.9
Pigment gallstones comprise only 15 percent of stones among people from Europe and the Americas, although these stones are more common among Southeast Asians.10