HDLs, the "good" cholesterol, are thought to carry cholesterol from the cells back to the liver so it can be removed from the body in bile. HDL is also thought to act as an antioxidant, preventing harmful changes to LDL cholesterol that make it more likely to damage the walls of arteries.
Measurement of the level of your HDL cholesterol is a powerful tool in assessing your risk of coronary heart disease. The higher the level of HDL cholesterol, the better it is for your heart.
In the early 1950s, scientists realized that patients with coronary heart disease had low levels of HDLs. A study done in 1966 found that men with low levels of HDL-2, a cholesterol-rich portion of HDL, were more likely to develop coronary heart disease.
Beginning in 1968, as part of the Framingham Heart Study, 2,815 men and women aged 49 through 82 had both their lipoproteins and fasting lipids measured. The men and women who had low levels of HDL cholesterol (less than 35 mg/dL) had eight times the risk of coronary heart disease as did those who had HDL-cholesterol levels above 65 mg/dL.
A 12-year follow-up showed that the group that had HDL levels below 53 mg/dL experienced 60 to 70 percent more heart attacks than the group with higher HDL levels.
In addition, the researchers found that low HDLs could predict the risk of heart attack in people who had the lowest total cholesterol levels. Finally, those people with low HDL cholesterol showed the most improvement when given LDL-lowering drug therapy, such as statins. This is because lowering LDL cholesterol reduces the risk of coronary heart disease.
Research has shown that a low level of HDL cholesterol is an independent risk factor of coronary heart disease. Even if LDL-cholesterol levels are within normal range, if HDL-cholesterol levels are low, the risk of a coronary event is increased.
Studies have indicated that for every 1 percent increase in HDL, the risk of coronary heart disease decreases by 2 to 3 percent. This means that even small improvements in HDL-cholesterol levels can prove markedly beneficial.
Most people can modify their diet and lifestyle to improve their HDL-cholesterol levels. Quitting smoking and losing weight can significantly increase HDL-cholesterol levels. Regular physical activity, moderate alcohol consumption, lower intakes of carbohydrates, and a Mediterranean-style diet have also been linked with improving levels of HDL cholesterol.
Despite evidence up to now indicating that HDL cholesterol is beneficial, some researchers now believe that not all HDL cholesterol is good, and they are conducting studies to determine if some forms of HDL promote inflammation, a key process involved in the development of atherosclerosis. Results of these studies are eagerly awaited.
Research also focuses on the specific proteins that are in HDL and LDL cholesterol. Learn about these apolipoproteins on the next page.
This information is solely for informational purposes. IT IS NOT INTENDED TO PROVIDE MEDICAL ADVICE. Neither the Editors of Consumer Guide (R), Publications International, Ltd., the author nor publisher take responsibility for any possible consequences from any treatment, procedure, exercise, dietary modification, action or application of medication which results from reading or following the information contained in this information. The publication of this information does not constitute the practice of medicine, and this information does not replace the advice of your physician or other health care provider. Before undertaking any course of treatment, the reader must seek the advice of their physician or other health care provider.