Alton, IL 

 

High HDL – Why is it Important? 

By Michael Klein, M.D.

Family Practice Physician  |  Saint Anthony’s Physician Group  |  618.462.2222

 

Good cholesterol. Bad cholesterol. HDL. LDL. What’s it all mean?

      Television ads present simplified drawings and descriptions, explaining the concept of “good” and “bad” cholesterol. Even so, High-Density Lipoproteins (HDL), the “good” cholesterol, is not very well understood, even by medical researchers.

      Most Americans know that Low Density Lipoproteins (LDL) and total cholesterol can be lowered by eating a diet lower in saturated fats and trans fats, losing weight and getting more exercise. The National Cholesterol Education Project (NCEP) recommends that you keep total cholesterol under 200 mg/dL and LDL below 100 mg/dL or even below 70 if you have other risk factors for heart disease.

      When these lifestyle changes are not enough, cholesterol-lowering medications such as statins are usually prescribed and, in most cases, they succeed in bringing total cholesterol and LDL down to normal levels.

      All of these cholesterol-lowering actions, however, do not necessarily have an effect on HDL, perhaps the most crucial component of cholesterol and the one that is more favorable when it is high.  NCEP guidelines recommend an HDL level greater than 40 mg/dL for a male or 50 mg/dL for a female. An HDL above 60 mg/dL may confer protection.

 

Clearing Out LDL 

      HDL particles are smaller and denser than other lipoproteins, with a higher proportion of protein. The major benefit of HDL is what is known as reverse cholesterol transport. Whereas LDL particles travel through arteries laying down plaque deposits, HDL does the reverse. These high-density lipoproteins act as scavengers, scouring the walls of blood vessels and carrying excess cholesterol back to the liver for processing.

      As they circulate through the blood stream collecting other cholesterol, they become larger, and the presence of large particles of HDL, on their way to the dumping ground in the liver, is usually considered a positive sign.

      Men tend to have lower concentrations of HDL, and smaller particles, than women, probably because of hormones. And men have an increased incidence of cardiovascular disease, at least until women pass menopause.

      HDL promotes the production of nitric oxide which plays an important role in keeping blood vessels healthy, dilating and contracting as they should and preventing problems such as high blood pressure and erectile dysfunction. Other substances in HDL reduce the clumping together of platelets and inhibit the formation of blood clots that are often the precipitating factor in a heart attack or stroke.

      HDL, in fact, seems to protect against every step of the disease process of atherosclerosis or hardening of the arteries. And it has been linked to a lower risk of metabolic syndrome, diabetes, peripheral vascular disease, kidney disease and even Alzheimer’s.

      In recently published [July, 2009] data from the prospective Japan Cholesterol and Diabetes Mellitus study, low levels of HDL were significantly related to an increased risk of stroke in subjects 65 years of age and older – a risk that became “prominent” after age 75.

 

Up with the Good 

      Lifestyle measures that are most effective at increasing HDL are also those considered most effective at maintaining a healthy heart and blood vessels:

• Regular aerobic exercise is recognized as the best way of improving HDL, and some studies indicate that duration is more important than intensity.  

• Weight loss is a good way of increasing HDL, particularly if your excess weight is stored mainly around your abdomen.
• Smokers can raise their HDL by quitting.
• Moderate alcohol consumption–one or two drinks a day–has a strong positive effect on HDL. This may be in part because the liver requests additional cholesterol to protect itself from the alcohol.
• In terms of diet, it’s important to focus not so much on a low-fat as a healthy fat regimen. Monounsaturated fats such as those in nuts, olive oil and canola oil and fatty fish high in omega-3 fatty acids are beneficial to the heart because they raise HDL, even if they increase the total fat in the diet.

 

      Most statins are designed mainly to lower LDL and total cholesterol; their effect on HDL is modest. Niacin is the most effective medication in this regard, increasing HDL by 15 to 30 percent. As a result, some doctors combine niacin with a statin for cholesterol therapy.

      Statin drugs – in combination with diet and exercise – have proven to be effective in bringing down the bad cholesterol. In the future, the focus will be on finding effective agents to increase the good cholesterol.

 

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