The gall bladder stores and concentrates bile during the fasting state. The gallbladder has the capacity to hold 40-50ml of bile. Adult humans produce 400 to 800ml of bile daily. Typically, bile is concentrated five-fold in the gall bladder by absorption of water and small electrolytes - virtually all of the organic molecules are retained.
Secretion into bile is a major route for eliminating cholesterol. Free cholesterol is virtually insoluble in aqueous solutions, but in bile, it is made soluble by bile acids and lipids like lethicin. In humans, roughly 500mg of cholesterol are converted to bile acids and eliminated in bile every day. Gallstones, most of which are composed predominantly of cholesterol, result from processes that allow cholesterol to precipitate from solution in bile.
Bile contains bile acids, which are critical for digestion and absorption of fats and fat-soluble vitamins in the small intestine. Many waste products are eliminated from the body by secretion into bile and elimination in feces. Between 90 and 95% of bile acids are reabsorbed, mainly from the lower half of the small intestine, and undergo enterohepatic recirculation; small quantities occur in the stools and very little is normally excreted in the urine. It should be noted that liver disease can dramatically alter this pattern of recirculation - for instance, sick hepatocytes have decreased ability to extract bile acids from portal blood and damage to the canalicular system can result in escape of bile acids into the systemic circulation. Assay of systemic levels of bile acids is used clinically as a sensitive indicator of hepatic disease.
The most abundant bile acids in human bile are chenodeoxycholic acid (45%) and cholic acid (31%). These are referred to as the primary bile acids. Within the intestines the primary bile acids are acted upon by bacteria and converted to the secondary bile acids, identified as deoxycholate (from cholate) and lithocholate (from chenodeoxycholate).
In normal individuals, additional administration of moderate quantities of bile acids or salts by mouth has no demonstrable effect, since there are enough bile salts present in the intestinal lumen to carry out all the absorptive functions. If there is a deficiency of bile salts, administration may be beneficial. Bile salts may cause some stimulation of intestinal movement.
The daily output of bile acids ranged from 1 to 2.3gm daily; when stimulated by bile, the daily output was increased fourfold Physiol. Rev. 1941, 21: p.435.
Dehydrocholic acid is the most commonly employed of the bile acids for medicinal purposes. The dose range is 250 to 750mg TID. The only contraindications listed are biliary obstruction and severe hepatitis (Martindale, 1972).
Deoxycholic acid administered orally in doses of 400 mg TID decreased appetite in four out of six patients Lancet, 1968, p.1066.
Two grams of ox bile salts were administered daily to a child of five years who had a congenital deficiency of bile salts, for a period of 11 months, with consequent improvement in fat absorption and no evidence of ill effects Lancet, 1955, p.1087.
Ox bile is often added as a component of digestive aids available from health food stores. Digest RC is a multiple herbal extract formulation which which contains ox bile and was introduced in Europe over 45 years ago and today sells over 100 million doses annually.