For years doctors have made a distinction about cholesterol. High levels of LDL (low-density lipoprotein cholesterol) was bad, and needed to be controlled through diet, and often medication.
HDL (high-density lipoprotein cholesterol), on the other hand, is often described as “good” cholesterol, and is believed to help guard against heart disease.
The American Heart Association states the prevailing view on its website, touting HDL's helpful role in removing LDL cholesterol from the arteries.
“Experts believe HDL acts as a scavenger, carrying LDL cholesterol away from the arteries and back to the liver, where it is broken down and passed from the body,” the Heart Association says.
It says a healthy level of HDL cholesterol may also protect against heart attack and stroke, while low levels of HDL cholesterol have been shown to increase the risk of heart disease.
But health researchers conducting a study in Baltimore are expressing second thoughts about that prevailing belief. At least, they think there should be a couple of caveats. They conclude that the protection you get from HDL all depends on the levels in the body of two other blood fats.
If these fats are not within normal levels, they say HDL loses much of its protective power.
“There’s no question that HDL does have a protective role, as we also confirm in the study, but HDL has been hyped-up,” said senior author Michael Miller, MD.
Miller, a professor of cardiovascular medicine at the University of Maryland School of Medicine says HDL really should be viewed as a third priority. Reducing LDL should come first, followed by a reduction in triglycerides.
Questions and answers
The researchers set out to answer a number of questions; they wanted to know if the level of HDL by itself determined the risk of a person developing heart disease. They also wanted to know how risk factors are affected if LDL and triglyceride levels are abnormal.
“Nobody has really looked at an isolated low and isolated high HDL, and whether or not other factors, such as triglycerides and LDL, make a difference in the risk of cardiovascular disease,” Miller said.
The study concluded that “good” cholesterol levels were not always a good predictor of heart disease risk. It also found triglyceride and LDL levels were a bigger influence on heart disease risk, regardless of whether or not the patient had high or low levels of HDL.