With 40 percent of all heart attacks and related cardiovascular problems occurring in people who have low levels of so-called "good" cholesterol, researchers have long sought medications to increase the amount of this type of cholesterol in the body's circulation.
But a new review of 31 randomized controlled trials published in the Journal of the American Medical Association suggests that so far, only modest evidence supports the use of most medications to raise levels of high-density lipoprotein (HDL) — good cholesterol. Some are even harmful.
The authors concluded that while efforts to lower low-density lipoprotein (LDL or “bad cholesterol”) “have consistently reduced cardiovascular disease risk, HDL-based approaches are much more complex and sometimes disappointing.” As a result, “the primary focus should be on LDL,” said review co-author Mehdi Shishehbor, D.O., of the Cleveland Clinic.
“The news is that not everything that raises HDL will be beneficial,” said Ronald Krauss, M.D., spokesman for the American Heart Association and director of atherosclerosis research at Children's Hospital Oakland Research Institute in California.
“HDL is a much more complicated issue than LDL,” said Prediman Shah, M.D., director of the Atherosclerosis Research Center at Cedars-Sinai Medical Center in Los Angeles. “It's not only important how much HDL there is, but what kind it is. Quality is as important as quantity. Is the function good or is it [a form of HDL] that doesn't do the job properly?”
There are many types of HDL, not all of which nurture the heart and blood vessels. The good kinds seem to carry fat out of arteries to the liver and perform functions in cell membranes and elsewhere. However, HDLs vary considerably in size, density and other chemical properties that change their ability to sustain health.
Certain kinds of HDL could even increase inflammation, clogging arteries rather than clearing them, and doctors currently do not have a simple way to tell this “bad” type of “good” cholesterol from the genuinely beneficial kind in their patients. Right now, only expensive tests used in research settings can sort this out.
Fortunately, lifestyle changes can help without negative side effects, according to the review. “The safest way to raise HDL is by weight loss, exercise and smoking cessation,” Shishehbor said.
The review also found support for moderate alcohol use — one or two drinks a day for men, one for women — although physicians do not recommend that nondrinkers take up drinking to protect their hearts. Raising HDL by eating fish or taking fish oil to increase intake of omega-3 fatty acids is another effective strategy, the review suggested.
As for pharmacological approaches, the review found that the most effective currently available drug to raise HDL is the vitamin niacin, taken in high doses. “Statins, niacin and fibrates are available pharmacologic agents that increase HDL; however, they may be associated with adverse side effects,” said Shishehbor, who recommended close medical supervision.