Although bile composition can vary according to a person's nutritional state, generally more than 80 percent of bile is water. Main components of bile include bile acids or salts, such as cholic and taurocholic acids; phospholipids, proteins and cholesterol. Bilirubin, a pigment that gives the characteristic color to feces, small quantities of copper and other metals, as well as inorganic salts, such as sodium and potassium, are also found in bile.
Bile is released into the small intestine, where it plays a key role in the digestion and absorption of fats and vitamins that are only soluble in fat. In addition to aiding digestion, bile also carries waste products, such as bilirubin, which are eliminated in the feces. Bilirubin is formed in the liver during the breakdown of old blood cells.
Special cells called hepatocytes produce bile and secrete it into small tubes or canaliculi, which are connected to wider ducts. In humans and most other animal species, a small organ called gallbladder stores and concentrates the bile until it is released in the intestine, during digestion. Water is absorbed and bile is concentrated five-fold when in the gallbladder.
The cholesterol contained in bile in the gallbladder can create lumps, which are called gallstones. Surgery is a common procedure to remove these stones, which can cause abdominal pain. If the liver stops the production of bile, the intestine cannot absorb fats and many fat-soluble vitamins, causing a condition called steatorrhea. Main symptoms of steatorrhea include white, grayish and greasy feces and nutritional deficiency.