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For years “bad” and “good” cholesterol have been the yin and yang of heart health, the two lipids around which so much advice revolves.

Bad cholesterol (low-density lipoprotein, or LDL) deposits excess cholesterol in your arteries, where it can build up into plaques, increasing the likelihood of heart disease and blood clots. Good cholesterol (high-density lipoprotein, or HDL) carries surplus cholesterol back to your liver so that it can be excreted.

To prevent heart disease, we’ve been told to keep LDL levels down and HDL levels up — with 45 milligrams per deciliter usually offered as a good target for the latter.

Sounds pretty straightforward, right? But according to several recent studies, good cholesterol alone has little ability to lower heart-disease risks, and more is not necessarily better.

Here’s what you need to know about the current thinking and the healthy-heart steps that are unlikely to change even if understanding of cholesterol does:

The new evidence on HDL

The first clue that the role of good cholesterol was more complicated than previously thought emerged when scientists tried to develop medications to raise HDL levels. The drugs they tested — niacin and cholesteryl ester transfer protein inhibitors — boosted HDL in the blood but failed to reduce cardiovascular-disease risks.

These results surprised doctors. We know that certain lifestyle changes, such as exercising more and quitting smoking, drive HDL levels up and heart-disease risk down. But increasing HDL levels artificially, without behavioral changes, doesn’t reduce risk at all.

“It turns out that HDL is not a very good therapeutic target,” says cardiologist Dennis Ko, a senior scientist at the Toronto-based Institute for Clinical Evaluative Sciences.

What’s more, Ko’s own research suggests that above a certain threshold, more HDL could increase health risks.

His team looked at 631,762 people and found that, during an evaluation period of about five years, those with HDL levels greater than 70 mg/dL (in men) or 90 mg/dL (in women) were more likely than those with HDL levels in the middle range to die for reasonsthat were unrelated to cardiovascular disease.

Forget the numbers?

As researchers work to figure out what these findings mean in the quest to keep hearts healthy, your doctors might still use your HDL levels (in conjunction with LDL and total cholesterol) to help predict your cardiovascular-disease risk. Consumer Reports’ experts say that very low HDL levels can be a sign of trouble and that the only meaningful way to raise them is through lifestyle changes.

“There is no evidence for a benefit from any HDL-raising drug,” says Steven Nissen, a cardiologist with the Cleveland Clinic. “It’s still important to pay attention to the numbers, but the main focus should be on making healthy choices.”

In other words, whether your HDL is low, high or somewhere in the middle, the prescription for a healthy heart will be the same: Don’t smoke, drink only in moderation, exercise regularly and stay away from trans fats (which are found in items such as fried foods and baked goods made with partially hydrogenated oils).

As Marvin M. Lipman, Consumer Reports’ chief medical adviser, notes, “Everyone agrees with the pursuit of a healthy lifestyle.”

Copyright 2017. Consumers Union of United States Inc.

For further guidance, go to ConsumerReports.org/Health, where more detailed information, including CR’s ratings of prescription drugs, treatments, hospitals and healthy-living products, is available to subscribers.