Question

How would a dietary resin that absorbs bile salts reduce plasma cholesterol levels?

Answer 1

Cholesterol is the precursor of bile acids. The liver uses cholesterol to produce bile acids, Bile acids are secreted into the intestines during normal digestion. The dietary resins bind to these acids, reducing their supply. In turn, this stimulates the liver to produce more bile acids, which uses more cholesterol. A major portion of the bile acids is absorbed from the intestinal tract and returned to the liver via the enterohepatic circulation. Only very small amounts of bile acids are found in normal serum. The dietary resin adsorbs and combines with the bile acids in the intestine to form an insoluble complex which is excreted in the feces. it results in a partial removal of bile acids from the enterohepatic circulation by preventing their absorption.

The increased fecal loss of bile acids due to the dietary resin administration leads to an increased oxidation of cholesterol to bile acids, a decrease in low-density lipoprotein plasma levels and a decrease in serum cholesterol levels. Although in man, the dietary resin produces an increase in hepatic synthesis of cholesterol, plasma cholesterol levels fall.