Cholesterol is a lipid, or type of fat. It helps the body perform many normal functions. Cholesterol is made in the liver and carries fats in the bloodstream.
In the body, cholesterol forms fat-protein chemicals called lipoproteins. Lipoproteins are grouped as very low-density lipoproteins (VLDLs), low-density lipoproteins (LDLs), also known as “bad cholesterol,” and high-density lipoproteins (HDLs). HDLs, “good cholesterol,” help remove lipids from the bloodstream, so higher HDL levels are better.
VLDLs and LDLs can clog arteries. High levels of cholesterol, LDLs, and triglycerides (fatty substances) increase the risk for hardening of the arteries (atherosclerosis) and heart disease.
Causes of hyperlipidemia include a family history, high-fat diet, being overweight, certain illnesses including diabetes, and some drugs.
Most people have no symptoms until their blood vessels are nearly closed or become clogged. Some people may have small fat deposits under the skin when lipids are very high. High cholesterol raises your risk for heart disease and heart attacks.
Blood levels of cholesterol, HDL, LDL, and triglycerides are measured. Preferred levels are less than 200 milligrams per deciliter (mg/dl) for cholesterol, less than 150 mg/dl for triglycerides, and over 40 mg/dl for HDLs. Recommended LDL levels are less than 130 mg/dl for most people but much lower (less than 70 mg/dl) for those with heart disease and diabetes.
Diet is the best way to reduce lipid levels. Lifestyle changes should reduce consumption of saturated fat to less than 7% of calories and cholesterol to less than 200 mg/day. Weight loss, exercise, and avoiding smoking are also important. Lowering daily carbohydrate intake may not directly reduce high cholesterol levels but is very helpful in producing weight loss in overweight and obese people.
Lipid-lowering drugs are used when diet and exercise are not enough. The main classes of drugs include statins, nicotinic acid, and omega-3 fatty acids.
Statins (e.g., atorvastatin) reduce cholesterol and LDL production. They are effective, usually well tolerated, and preferred for higher cholesterol and LDL levels. They can have side effects such as muscle aches and liver abnormalities.
Nicotinic acid helps lower VLDL levels and increase HDL levels. Side effects (itching, facial flushing, liver problems) limit its use.
Omega-3 fatty acids (over-the-counter fish oil supplements) may help patients with high triglyceride, low HDL, and moderate cholesterol levels, but their overall benefit in preventing heart disease has not been proven.
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