Q: For a long time, I thought a high “good” cholesterol level balanced out the negative health effects of a high “bad” cholesterol level. Is that no longer true?
A: First, some definitions. Since cholesterol is a fat, it can’t travel alone in the bloodstream. To get around this problem, the body packages cholesterol and other lipids into minuscule protein-covered particles that mix easily with blood. These tiny particles, called lipoproteins (lipid plus protein), move cholesterol and other fats throughout the body.
The two lipoproteins that have gotten the most attention are low-density lipoprotein (LDL) cholesterol, the so called “bad” cholesterol, and high-density lipoprotein (HDL), also known as “good” cholesterol.
- LDL is known as “bad” cholesterol because it delivers cholesterol to tissues and is strongly associated with the buildup of artery-clogging plaque, raising risks for heart attacks and strokes. HDL particles have been called “good” cholesterol because some of them remove cholesterol from circulation and from artery walls and return it to the liver for disposal.
- The harmful effects of a high LDL level have been proven many times over. And lowering LDL with diet, exercise and medicines clearly reduce heart attack and stroke risk.
- For HDL, the story is more complex than doctors initially thought. It’s true that people with naturally high HDL levels tend to have fewer heart attacks, while those with lower HDL values have more. But raising HDL cholesterol has not led to improved cardiovascular outcomes.
Instead of acting as the good guy that helps lower heart disease risk, HDL may be more of a bystander. HDL appears to be a marker for other factors that raise or lower the risk of a heart attack.
People with low HDL levels tend to have other problems closely linked to higher cardiovascular risk, such as being overweight with a big belly indicating accumulation of fat around the abdominal organs. Also, a low HDL is associated with high blood pressure and prediabetes or full-blown diabetes. It’s likely that those factors, rather than the low HDL, are behind the higher risk.
On the flip side, people with high HDL shouldn’t assume that it cancels out a high LDL. Your main goal should be to keep your LDL in a healthy range.