Blocking Absorption of Dietary Cholesterol

BioFiles 2007, 2.7, 9.

BioFiles 2007, 2.7, 9.

Dietary cholesterol is obtained from foods derived from animal sources that are rich in fat content. A healthy adult only needs to ingest about 30% of the daily cholesterol requirement. Obtaining more than this amount from dietary cholesterol can lead to increased cholesterol levels and serious health risks.

Dietary cholesterol is absorbed within the lumen of the small intestine. Bile salts produced from cholesterol in the liver interact with phospholipids to produce a biliary micelle that is transported via bile into the lumen. Dietary cholesterol in the lumen is easily incorporated into these micelles and together with the already present biliary cholesterol can now be absorbed into the enterocytes that make up the walls of the lumen. The micelles enter the cell by a channel know as Niemann-Pick C1 Like 1 protein (NPC1L1). Once in the cells the cholesterol can either be pumped back out into the lumen or it can be esterified for transport within chylomicrons.

Preventing the absorption of this dietary cholesterol has become a key area in cholesterol related research. Plant sterols and stanols have been shown to be effective inhibitors of cholesterol absorption. Ingested as part of a normal diet, plant sterols and stanols are very similar in structure to cholesterol. They actually have a stronger binding affinity than cholesterol to the biliary micelles that aid in absorption. Because of this the sterols and stanols can displace cholesterol from the micelles thus preventing its absorption.

Recently, inhibitors that block the absorption of the biliary micelles into the enterocytes have also been used to block the uptake of dietary cholesterol.

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