Bile salts metabolism

Oakenfull, D.G. and Sidhu, G.S. 1983. A physico-chemical explanation for the effects of dietary saponins on cholesterol and bile salt metabolism. Nutr. Rep. Int. 27, 1253-1259. 

Understand the mechanisms involved in lipid digestion and absorption, including bile salt metabolism. 

Nl. Nair, P. P., Enzymatic cleavage of bile acid conjugates. In Bile Salt Metabolism (L. Schiff,. B. Carey, and J. M. Dietschy, eds.), pp. 172-183. Thomas, Springfield, Illinois, 1M9. 

This chapter deals with the metabolism of bile salts in man, especially as it relates to disease, particularly liver disease. The important role of bile salts in lipid absorption and gallstone formation is discussed in other chapters and will therefore not be considered here. The alterations in bile salt metabolism will be discussed in relation to disease categories in an effort to present a clearer overview of the general subject. A more detailed presentation of alterations in specific diseases has recently been prepared (1). 

Manipulation of dietary fats to alter serum cholesterol concentrations has relatively little effect on bile salt metabolism in man when measured by... 

X. ALTERED BILE SALT METABOLISM WITH HEPATOBILIARY DISORDERS... 

The two primary bile salts in man, cholate and chenodeoxycholate, are synthesized exclusively in the liver, and consequently measurement of their concentrations in blood or bile often yields useful information about the liver and its response to injury. Bile salt metabolism is altered in two important ways with liver injury. The concentrations of bile salts in the blood increase, and the concentration ratio in both blood and bile changes. 

Neomycin is a polybasic, poorly absorbed antibiotic which forms insoluble precipitates with bile salts (99). It lowers serum cholesterol concentrations in man (100-102) and chickens (99) and increases fecal bile acid excretion. It inhibits the hepatotoxic effects of lithocholic acid ingestion in chickens (99) and prevents bacterial conversion of cholate to deoxycho-late (103). Neomycin, 6-12 g/day, induces a malabsorption syndrome, with mucosal changes similar to those of sprue (104). Bile salt metabolism is thus affected in at least three ways by neomycin (1) a binding effect similar to that of cholestyramine, (2) suppression of deconjugation and secondary bile formation caused by antimicrobial properties, and (3) possible impairment of absorption of bile salts by intestinal mucosa. The first probably accounts for most of the increased fecal excretion of bile salts. 

NEWER ASPECTS OF BILE SALT METABOLISM IN INTESTINAL DISEASE ... 

Newer Aspects of Bile Salt Metabolism in Intestinal Disease... 

Similar studies to those described have been performed in only a limited number of patients with ileal disease in the absence of resection or bypass (3,9-11) five with active regional ileitis and two with radiation damage. The results of isotope dilution studies (Table I, Fig. 2), fecal excretion measurements, and measurements of luminal bile salt concentration have thus far been similar to those reported in ileectomized patients, suggesting that inflammatory disease of the ileum per se results in a loss of enterohepatic circulation of bile salts. It is not known whether this absorptive defect is repaired in remission of regional enteritis. The course of this disease is characterized by variations in activity whether or not these defects in bile salt metabolism vary in accordance with this natural history of the disease is one of several questions requiring study. 

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