There are three types of cholesterol you should know about:
1. HDL (high density lipoprotein) cholesterol, also known as
the good cholesterol.
2. LDL (low density lipoprotein) cholesterol, also known as the
HDL cholesterol removes cholesterol from the blood vessel wall and delivers it to the liver for final disposal. In this way, it serves to keep the walls of the blood vessels free of cholesterol deposits.
That's why it’s known as the good cholesterol. Think of it as a roto-rooter for your blood vessels!
LDL cholesterol gets deposited into the blood vessel wall and subsequently leads to narrowing of the blood vessels. That's why it’s known as the bad cholesterol. Think of it as the growing clog in your pipes!
There are two types of LDL particles:
A. Large, fluffy particles, also known as “pattern A.”
B. Small, dense particles, also known as “pattern B.”
Small, dense LDL particles (pattern B) are more harmful than the large, fluffy type (pattern A)
Triglycerides are a form of fat circulating in the blood. High triglycerides cause deposition of cholesterol in the blood vessel walls which leads to narrowing of the blood vessels.
Patients with Insulin Resistance Syndrome typically have:
1. Low HDL
2. High Triglyerides
Cholesterol gets deposited easily in the blood vessels of these patients and the build-up of cholesterol cannot be cleansed out efficiently due to low level of HDL cholesterol. Consequently, these patients are at very high risk for narrowing of the blood vessels.
HDL cholesterol and triglyceride level serves as an extremely useful test to diagnose Insulin Resistance Syndrome. If your HDL is low and/or your triglyceride level is high, you have Insulin Resistance Syndrome.
Low HDL cholesterol has been known to be a strong risk factor for coronary artery disease for a long time. In 1977, the results of the famous Framingham Heart Study were published in the American Journal of Medicine. In this study, HDL cholesterol was found to be the most potent lipid predictor of coronary heart disease.
Several other studies including the Coronary Primary Prevention Trial (CPPT), the Multiple Risk Factor Intervention Trial (MRFIT), and the Lipid Research Clinics Follow-up Study (LRCF) further confirmed the strong relationship between low HDL cholesterol and coronary artery disease.
Raising HDL cholesterol reduces the risk for heart attack. A 1% increase in HDL cholesterol is associated with a 3% decrease in risk of heart disease. This impressive role of HDL cholesterol in preventing heart attack was shown in the famous Veterans Affairs HDL Intervention Trial (VA-HIT). The results of this study were published in the New England Journal of Medicine in 1999.
In the U.S., the National Cholesterol Education Program (NCEP) published new guidelines for cholesterol detection and treatment in 2001. This national panel of experts strongly emphasize the importance of HDL cholesterol and Insulin Resistance Syndrome (also known as Metabolic Syndrome). According to the new guidelines, cholesterol testing should include LDL cholesterol, HDL cholesterol and triglycerides. For more information regarding cholesterol and insulin resistance, please read the section under "Heart."
This article was written by Sarfraz Zaidi, MD, FACE. Dr. Zaidi specializes in Diabetes, Endocrinology and Metabolism.
Dr. Zaidi is a former assistant Clinical Professor of Medicine at UCLA. Currently, he is Director of the Jamila Diabetes and Endocrine Medical Center in Thousand Oaks, California.
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