When you talk to your doctor about your cholesterol, you probably have heard about two different kinds: the bad and the good. LDL (or low-density lipoprotein) cholesterol, classified as “bad,” deposits cholesterol particles in your arteries and increases your risk for a heart attack. HDL (or high-density lipoprotein) cholesterol is the “good” kind. It picks up those cholesterol particles that have been stuck in the arterial wall and shuttles them off to the liver to be excreted from your body.
Having high LDL levels puts you at a higher risk for heart disease. People with naturally high HDL levels seem to be more protected. But if you have low HDL, does raising it protect you from a heart attack?
Not necessarily, says Om Ganda, M.D., Director of the Lipid Clinic at Joslin Diabetes Center and Associate Professor of Medicine at Harvard Medical School. “Even though population-wise there’s a very good correlation between the high level of HDL cholesterol and lower risk for heart disease, the question of whether or not raising it in someone who has a low HDL cholesterol [decreases that person’s risk] has not been proven,” he says.
As of right now, HDL cholesterol is understood more as a biomarker for the risk of heart disease. If someone has naturally high HDL, he or she is probably genetically more protected against heart attacks. The key to heart attack prevention, he says, is making sure your LDL cholesterol is low.
The strongest evidence of this comes in the form of two international studies published a few years ago. Both studies looked at people with previously high risk for cardiovascular disease but who had gotten their LDL levels under control with statins, a class of drug proven to be effective at lowering bad cholesterol. These people also had HDL levels below 40 mg/dL, which is considered by the NIH a major risk factor for heart disease.
The researchers gave some of the study participants another drug called niacin, which is known to increase HDL cholesterol by 25 percent. The rest of the study participants got a placebo. Both groups continued to keep their LDL cholesterol in tight control with statins.
“In both these studies, interestingly, there was not a slightest improvement in the cardiovascular outcomes [in the people who raised their HDL cholesterol],” says Dr. Ganda. “It’s one of the best proofs that we have with two large multinational studies showing that if your LDL is very good, raising HDL cholesterol doesn’t make any difference. And it makes sense, when you think of it. Because if your plaque is depleted of cholesterol by the statin or by diet or a combination, then there’s not much cholesterol there for the HDL particle to get rid of.”
There is one caveat: these studies were done on people with LDL in the healthy range. There haven’t been any studies looking into the effects of raising HDL in people with high LDL.
There’s no danger to raising your HDL cholesterol levels, however, by lifestyle changes. You can do that by losing weight, exercising consistently, and controlling your blood sugar. All of these actions also lower your triglycerides levels, which is a bonus.
The bottom line? “It doesn’t hurt to raise HDL cholesterol,” says Dr. Ganda. “We think that a higher level is good just because there’s a good correlation. But it remains to be proven by any long term clinical studies that by proactively raising it, you’ll actually lower your risk.”
For more information about Joslin’s Lipid Clinic or to make an appointment, click here.