Gallstones are diagnosed in 10% to 15% of Americans each year. The stones form from components of bile in the gall bladder, a small pear-shaped organ beneath the liver that stores and releases the liquid bile into the small intestine. Bile, a yellow-green fluid made by the liver, consists largely of cholesterol, bilirubin and bile salts. The salts are derived from bile acids: “Seventeen enzymes convert cholesterol into bile acids, which are transformed into bile salts by the association with Na+ or K+ ions.“
Bile is released by the gall bladder into the duodenum during digestion to help separate fats. Bile also helps the body absorb fat-soluble vitamins like vitamins A, D, E and K. However, stones can form when cholesterol in the liquid bile forms crystals that become stones. Most stones, about 80%, consist primarily of cholesterol.
Gallstones may be as small as a grain of sand but as large as a golf ball. Typically, when stones form, they are eliminated through the digestive system without symptoms. However, if a stone becomes trapped in a bile duct it can cause sudden pain – treatment for gallstones includes surgery.
According to the NIH, women are more likely to develop gallstones or those with higher or a “supersaturation” of cholesterol in their bile. A 2013 study found that high serum cholesterol and LDL low-density lipoproteins levels were associated with high cholesterol gallstone rates.
The liver is a major synthesis site for cholesterol which is excreted by the biliary and digestive systems. Biliary cholesterol is reabsorbed if it is not eliminated by the bowel. Slow intestinal transit and reabsorption of cholesterol is a contributing factor in gallstones. Other factors include obesity, rapid weight loss, sedentary lifestyle, and a low fibre diet.