Diet Effects on Plasma Lipoproteins - Essay Example

Cholesterol and triacylglycerol are transported in the blood as lipoproteins. Ordovas ( 2005 ) defined lipoproteins as “Lipoproteins are generally spherical particles, with a surface layer composed of phospholipid with the fatty acids oriented toward the core of the particle”.
The lipoproteins are chiefly those chylomicrons, named Very low-density lipoprotein (VLDL), Immediate-density lipoprotein (IDL), Low-density lipoprotein (LDL), High-density lipoprotein (HDL).
Chylomicrons are the largest lipoproteins, consisting mainly of triacylglycerol with apo-48 and apoA, -C, and -E. Triacylglycerol is hydrolyzed with endothelial-bound lipoprotein lipase, changing the chylomicron into a chylomicron remnant rich in cholesteryl ester. These remnants are removed from the circulation by interaction with the remnant receptors mainly present on hepatocytes.
Chylomicron remnant rich in cholesteryl ester is made from chylomicron when triacylglycerol is hydrolyzed with lipoprotein lipase that moves towards endothelial. Mainly by the contact with remnant receptors found mostly on hepatocytes, the chylomicron remnants are removed. Triacylglycerol with apoB-48, and apoA, -C, and –E are present in chylomicrons which are the major lipoproteins.
Very low-density lipoproteins are secreted mainly by the liver, with apoB-100 and apoE on their surface. They are transformed into mature VLDLs by accumulating cholesterol ester, apoC, and apoE from HDLs. They then either interact with lipoprotein lipase to convert into IDLs, which can be taken up by the liver, or convert to LDLs by interacting with hepatic triglyceride lipase. VLDL particles vary in size. Small VLDL is converted into LDL, via IDL, to a greater extent than large VLDL, which is converted to a form of IDL that appears to be removed from the plasma before conversion to LDL.
Mostly, the liver discharges very low-density lipoproteins with an exterior of apoB-100 and apoE. Then, they build up with apoC, and apoE from HDLs and turn into mature VLDLs.