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Cholesterol is a thick, wax-like substance which is both produced by the body and ingested through the diet. Despite its bad reputation, cholesterol does perform some valuable services, including aiding digestion, contributing to cell membrane formation, and helping convert absorbed sunlight into vitamin D. The presence of too much cholesterol in the body — particularly in the form known as bad cholesterol — can significantly raise one’s risk of heart disease and stroke, however. Conversely, the form known as good cholesterol can help carry excess cholesterol out of the bloodstream, and is thus necessary in certain amounts. Understanding the difference between good and bad cholesterol can be critical to caring for cardiovascular health.
Perhaps the core difference between good and bad cholesterol is their composition. As cholesterol is a lipid, or fat, it cannot dissolve in the bloodstream. Therefore, when new cholesterol enters the blood, the body dispatches pilot-like protein molecules which bind to the cholesterol and guide it through the bloodstream. When this newly formed compound contains only a small amount of these pilot proteins, it is called low-density lipoprotein (LDL), or bad cholesterol. Conversely, when the compound contains large amounts of proteins, it is known as high-density lipoprotein (HDL), or good cholesterol.
The protein content of this compound affects the way the compound operates, leading to the second difference between good and bad cholesterol. As LDL (bad) cholesterol moves through the blood, it may leave plaque, or hard deposits, on arterial walls. Plaque narrows the arterial passageways, increasing the risk of blood clots, heart attack, and stroke.
HDL (good) cholesterol, on the other hand, seems to perform quite differently. While as of 2010, researchers do not fully understand how HDL (good) cholesterol works, they believe it acts as a kind of arterial broom which sweeps away excess cholesterol as it moves through the bloodstream. This excess cholesterol is carried to the liver and then eliminated. Some researchers think that good cholesterol may even clear away some of the arterial plaque deposited by bad cholesterol.
Once the difference between good and bad cholesterol is understood, the next step for many is having the cholesterol tested to determine how much of each compound is present in the blood. If a cholesterol test reveals high levels of bad cholesterol, low levels of good cholesterol, or both, a physician can provide advice about improving these figures. Common cholesterol improvement techniques include eating a diet low in cholesterol and saturated fats, losing excess weight, quitting smoking, and exercising regularly.