HDL helps the cholesterol
The endogenous path for cholesterol transport begins by the synthesis of VLDL particles in the liver, which are rich in triacylglycerols and cholesterol. VLDL transport the absorbed fats to the various organs and tissues, and then are converted into LDL.
LDL are the main cholesterol transporters, being in charge of 60-80% of cholesterol plasma. LDL particles provides cholesterol to peripheral cells, for cell membranes synthesis and tissues which synthesize hormones steroids. If in the blood flows too much LDL particles, some cells, called macrophages or lipofage, captures them fixes them on the arterial walls, leading to narrowing arteries in time.
With the electrophoresis help, were identified several LDL subclasses. Large LDL particles and less dense are found usually in premenopausal women and men with less risk small of coronary disease, while smaller and denser particles are associated with an increased risk of heart attack.
For several years is known that small and dense LDL particles are particularly harmful; 50% of men and 20% of women before menopause, who have coronary heart disease, have this dangerous LDL cholesterol, also called type B.
Small and dense LDL particles increase three times the risk of coronary heart disease, increase the risk of type 2 diabetes and make the narrowing of the arteries to progress twice faster than in subjects who is not found this type of LDL.
Why are these small and dense LDL particles so harmful?
- With a higher electrical density, they enter twice faster in arteries than do normal LDL particles.
- After each meal, small and dense particles remain two hours longer in circulation than normal particles.
A very important fraction is the HDL, with HDL2 and HDL3 subfractions.
LDL, both synthesized by the liver, as well as intestine, detects and captures the unesterified cholesterol in cell membranes and other lipids (phospholipids and triacylglycerol) and protein (lipoprotein A, I and E) from triacylglycerol-rich lipoproteins (chylomicrons and VLDL). As these particles undergo lipolysis process, HDL transports them back to the liver. Here, LDL particles converts again in VLDL, and cholesterol is converted to bile acids or is excreted directly in the bile. So HDL cleans our arteries and protects us from atherosclerosis.
While most researchers attributed the protective role of HDL from atherosclerosis, cholesterol transport from the tissues and the blood vessels to the liver action, today it is known that HDL carries enzymes that can counter the biological effects of oxidized LDL.