You’ve probably heard HDL referred to as the “good” cholesterol. But you might not know what makes it so good. Why is some cholesterol helpful to the heart and other cholesterol (namely LDL) harmful?
A little about LDL
Cholesterol travels through the bloodstream in protein packages called lipoproteins. The lipoprotein of greatest concern is low-density lipoprotein (LDL), the so-called bad cholesterol. If your body produces more LDL than the cells can absorb, it lodges in artery walls and contributes to the buildup of atherosclerotic plaque.
Driving down LDL has been the main target for improving cholesterol levels. Powerful cholesterol-lowering drugs called statins are available to do just that. Studies have shown that taking a statin can cut the risk of developing and dying from heart disease by 30 percent to 40 percent.
And on to HDL
But there’s more to the story of cholesterol and cardiovascular risk than LDL. Another key player is high-density lipoprotein (HDL), dubbed the “good” cholesterol. HDL removes LDL from the artery walls and ferries it back to the liver for processing or removal.
How HDL helps
Cholesterol travels in the blood attached to lipoproteins. Low-density lipoprotein (LDL) enters the walls of arteries, where it contributes to the buildup of atherosclerotic plaque. High-density lipoprotein (HDL) removes LDL from the artery walls and carries it back to the liver. HDL also helps quell inflammation and protect the cells lining the arteries’ inner surface (endothelium).
HDL also acts as:
~an antioxidant. Researchers believe antioxidants can protect against coronary artery disease by preventing LDL cholesterol from reacting with oxygen, which leads to the progressive thickening and hardening of the walls of arteries.
~an anti-inflammatory. Though inflammation is an essential part of the body’s defenses, it can cause problems, too. In the heart, inflammation can trigger atherosclerosis, keep the process smoldering, and influence the formation of artery-blocking clots, the ultimate cause of heart attacks and many strokes.
~an antithrombotic. Thrombosis is the forming of clots, and preventing these clots from forming in the coronary arteries can prevent heart attack and stroke.
People with low levels of HDL are more likely to have heart attacks and strokes; high levels appear to be protective. In the Framingham Heart Study, low levels of HDL were an even more potent risk factor for heart disease than high levels of LDL. Other studies have linked high HDL levels to a reduced risk of stroke, greater longevity, and better cognitive function in old age.
Harvard Medical School