The amount of absorbed cholesterol depends on cholesterol intake, biliary cholesterol secretion, and cholesterol absorption efficiency, which in turn is affected by
(a) the amount and the condition of absorptive intestinal mucosa and
(b) micellar solubilization of cholesterol with the aid of bile acids
When foods are consumed, cholesterol arrives in the small intestine from both the diet and bile. Dietary cholesterol accounts for approximately 300 mg/d, whereas biliary cholesterol is estimated to contribute 800∼1,400 mg/d.
Biliary cholesterol enters the small intestine unesterified, along with the other major components of bile (phosphatidylcholine and bile acids). As the components of bile mix with dietary lipids, micelles form spontaneously. Micelles are created by interactions between bile salts and the plasma membrane of hepatocytes. Micelles are formed when a critical concentration of lipid from bile mixes with lipids entering the small intestine from the diet.
Cholesterol is absorbed from micelles into the intestinal wall through protein channel, Niemann-Pick C1 Like 1 protein (NPC1L1) on the enterocyte plasma membrane.
Cholesterol absorption
