Intestinal absorption of dietary fats and cholesterol

Intestinal absorption of dietary fats and cholesterol is not a single molecule or receptor but rather a complex physiological process involving multiple proteins, enzymes, transporters, and cellular pathways. The process includes: - **Emulsification** of dietary lipids by bile salts in the small intestine. - **Enzymatic digestion** by pancreatic lipases to break down triglycerides into monoglycerides and free fatty acids[1][4]. - Formation of **micelles**, which are complexes containing bile salts, fatty acids, monoglycerides, phospholipids, and cholesterol that facilitate lipid transport across the aqueous environment to the enterocyte surface[4]. - **Absorption into enterocytes** via both passive diffusion (for some fatty acids) and protein-mediated transporters. Key proteins include: - *Niemann-Pick C1-Like 1* (**NPC1L1**) – critical for cholesterol uptake. - *ATP-binding cassette* transporters (**ABCG5/ABCG8**) – limit excess sterol uptake. - *Microsomal triglyceride transfer protein* (**MTP**) – essential for chylomicron assembly[3][5]. - *Apolipoprotein B48* – required for chylomicron formation. - Other factors like lysophosphatidylcholine acyltransferase (**LPCAT3**) influence membrane fluidity affecting fat uptake[5]. After entry into enterocytes: - Lipids are reassembled into triglycerides/cholesteryl esters, - Packaged with apolipoproteins as **chylomicrons**, which are secreted into lymphatics then blood circulation. This process is regulated by hormones (e.g., cholecystokinin), gut microbiota composition[5], genetic factors affecting transporter expression/activity[3], diet composition (fiber reduces cholesterol absorption)[1], and enterohepatic recycling of bile salts. Therapeutic targeting focuses on specific molecules within this pathway—such as NPC1L1 inhibitors (*ezetimibe*) to reduce cholesterol absorption—or MTP inhibitors to lower plasma lipid levels. However, these drugs target individual proteins rather than the entire process described here. Because "intestinal absorption of dietary fats and cholesterol" refers broadly to a physiological function—not a discrete therapeutic target or molecule—the entry is considered incorrect as a canonical drug target name. For structured data purposes, it should be replaced with specific molecular entities such as “Niemann-Pick C1-Like 1” or “Microsomal triglyceride transfer protein” when referring to druggable targets involved in this pathway[3][5].