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HDL
HDL Cholesterol is also known as good cholesterol. Its formal name is high-density lipoprotein (hdl cholesterol).
HDL Cholesterol
HDL Cholesterol is also known as good cholesterol. It is the type that is found in unsaturated and poluunsaturated fats. About one-third to one-fourth of blood cholesterol is carried by high-density lipoprotein (HDL). It is known as the "good" cholesterol because a high level of it seems to protect against heart attack. Low levels increase the risk for heart disease. Medical experts think that HDL tends to carry cholesterol away from the arteries and back to the liver, where it's passed from the body. It is thought by some experts that it removes excess cholesterol from plaque in arteries, thus slowing the buildup.
HDL Cholesterol - High Density Lipoproteins
High density lipoproteins (HDL) form a class of lipoproteins, varying somewhat in their size and contents, that carry cholesterol from the body's tissues to the liver.
Because it can remove cholesterol from atheroma within arteries, and transport it back to the liver for excretion, they are seen as "good" lipoproteins. When measuring cholesterol, any contained in HDL particles serve as protection to the body's cardiovascular health. (In contrast to "bad" LDL cholesterol.)
HDL are the smallest of the lipoproteins. They are the densest because they contain the highest proportion of protein. The proteins they contain are called apolipoproteins. The liver synthesises these lipoproteins as complexes of apolipoproteins and phospholipid, which resemble empty flattened spherical protein particles. They are capable of picking up cholesterol, carried internally, from cells they interact with. A plasma enzyme called lecithin: cholesterol acyltransferase (LCAT) converts the free cholesterol into cholesteryl ester (a more hydrophobic form of cholesterol) which is then sequestered into the core of the lipoprotein particle eventually making the newly synthesized HDL spherical. They increase in size as they circulate through the bloodstream, as they internalize more cholesterol molecules. Thus it is the concentration of large HDL particles which more accurately reflects protective action, as opposed to the concentration of total HDL particles. This ratio of large HDL to total HDL particles varies widely and is only measured by more sophisticated lipoprotein assays using either electrophoresis, the original method developed in the 1970s or newer NMR spectroscopy methods, developed in the 1990s.
Men tend to have noticeably lower HDL levels, with smaller size and lower cholesterol content, than women. Men also have an increased incidence of atherosclerotic heart disease.
Raising HDL Cholesterol
Raising the levels of hdl in the body has in the last few years been focused upon in the fight against heart disease. In the past most studies have focused on how lowering LDL or "bad" cholesterol that can reduce the risk or coronary heart disease. But recently, researchers have identified that HDL acted as an independent factor and was also critical in the overall health of your heart. The National Cholesterol Education Program's new guidelines now recognize that low HDL levels as a strong independent risk factor for coronary artery disease.
We know that a high density lipoprotein is a complex molecule made up of lipids, cholesterol, and protein. The way it works is that it acts as much like a bottom feeder of a fish tank. It cleans off the walls of blood vessels, thus removing excess cholesterol, LDL. It then carries this cholesterol to the liver where it is processed.
Doctors do still strongly recommend lowering LDL but are now including recommendations that raising HDL is another important factor to reduce risk of heart disease.
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