If you've just received a good report at a recent physical because your LDL cholesterol (aka the "bad" one) was low and your HDL cholesterol (aka the "good" one) was high, you’re probably feeling pretty confident about your heart health. Not so fast, say the authors of a new study.

That’s because in some instances, high-density lipoprotein (HDL, the "good" cholesterol) can become hazardous to your health. In fact, research shows that HDL can function abnormally, and begin to clog up and damage the arteries (the tubes that carry blood from the heart through the body) instead of carrying LDL cholesterol away from the arteries, which is how HDL is thought to protect against heart disease.

New Insight Into HDL Cholesterol

"HDL cholesterol is much more complicated than we thought," says Stanley Hazen, MD, PhD, section head of preventive cardiology and rehabilitation at the Miller Family Heart and Vascular Institute at the Cleveland Clinic. "We are finding that not all HDL is good." In the recent study, higher levels of dysfunctional HDL increased the participants’ risk of heart disease, regardless of their total HDL cholesterol levels.

HDL contains both cholesterol and protein; the protein is what provides the heart protection. But researchers have found that in the artery wall, a large amount of this protein can become oxidized. "Oxidation is the development of free radicals," says Suzanne Steinbaum, DO, director of the Women and Heart Disease program at Lenox Hill Hospital in New York City, and the author of Dr. Suzanne Steinbaum’s Heart Book. "These free radicals can damage the lining of the artery and lead to the build up of plaque formation." This plaque build-up contributes to the development of heart disease.

In the near future, a blood test that detects problematic HDL may be available, Hazen says: "The test we have developed measures the amount of dysfunctional HDL," he explains. "It gives you a window, or a gauge, as to what is happening in the artery wall." The commercial version of the blood test may be available later this year through Cleveland Heartlab, a spinoff of the Cleveland Clinic, Hazen adds.

What You Can Do Now

Blood tests aside, there are plenty of steps you can take to help ensure that your heart is healthy:

  • Get moving. "Be sure to get enough exercise," Hazen says. The American Heart Association recommends 150 minutes of moderate-intensity exercise per week (or about 30 minutes five days per week) or 75 minutes of vigorous activity per week (15 minutes five days a week.) If you are new to exercise, be sure to check with your doctor before getting started.
  • Eat right. The right diet is also important, says Steinbaum. She recommends the Mediterranean diet, which includes plenty of vegetables such as leafy greens, fruit, whole grains and beans, fish and seafood, and olive oil. While a glass of red wine with dinner is permitted, followers of the Mediterranean diet avoid red meat, sweets, and processed foods. It’s also essential to consume foods that are rich in bioflavonoids (health-promoting compounds usually found in brightly colored fruits and vegetables), antioxidants (substances that prevent or delay cell damage), and polyphenols (a specific kind of antioxidant), which help maintain heart health, Steinbaum says. "Dark chocolate, berries, tea, and red wine are all good sources of these," she adds.
  • Reduce stress. Having too much stress in your life stresses your body, too. Steinbaum advises learning relaxation exercises, making a conscious effort to stop overextending yourself, and consider taking up yoga.
  • Kick the Habit. If you smoke, quit. Enroll in a smoking cessation program or learn strategies from your health care provider on how to quit.

Stanley Hazen, MD, PhD, reviewed this article.


Stanley Hazen, MD, PhD. Cleveland Clinic Lerner Research Institute. 

Suzanne Steinbaum, DO, Lenox Hill Heart and Vascular Institute of New York. 

Ying Huang et al. "An Abundant Dysfunctional Apolipoprotein A1 in Human Atheroma." Nature Medicine. Accessed 26 January 2014.  

Cool, Lisa Collier. "Study: 'Good' Cholesterol Can Be Bad for Your Heart." Accessed 27 January 2014.

Innes, Emma. "When Good Cholesterol Turns BAD," 27 January 2014. 

"Good Vs. Bad Choleterol." American Heart Association. Page last reviewed on April 21,2014.

"Antioxidants." MedlinePlus. Page updated June 6, 2014. 

"What Is Artherosclerosis?" National Heart, Lung, and Blood Institute. Page updated July 1, 2011.