Many people think of cholesterol as something that should be as low as possible. After all, high cholesterol is a well-documented risk factor for heart disease.
Tens of millions of Americans take cholesterol-lowering drugs or should be taking them, according to the Centers for Disease Control and Prevention (CDC).
However, cholesterol levels are more complicated than that. High-density lipoprotein (HDL) cholesterol, often known as "good" cholesterol, is actually beneficial for the heart.
In this article, we examine whether or not HDL cholesterol can ever be too high. We also take a look at what healthy levels are, and what can happen if HDL falls out of this range.
There are two main types of cholesterol in the body, and only one of them is usually considered to be a risk to heart health.
Low-density lipoprotein (LDL) cholesterol contributes to the fatty buildup that can clog the arteries. When this buildup clogs or narrows the arteries, a heart attack or stroke is more likely to occur. With LDL cholesterol, lower is better.
HDL cholesterol is useful for the heart. HDL cholesterol may remove LDL cholesterol from the blood and transport it to the liver, where it can be processed and eliminated. A higher HDL number is desirable because it usually signals a lower risk of heart disease.
If HDL protects the heart, should it be as high as possible? The answer may depend on several factors.
Most people will find that their HDL cholesterol does not climb to levels that are considered "too high." Though no upper limit has been established, HDL cholesterol does not naturally elevate to unhealthy high levels in people with normal cholesterol processing and metabolism.
In rare cases, however, HDL cholesterol can become too high.
An article in the journal Science discusses a rare genetic variant that may cause exceptionally high HDL levels. The genetic variant alters the way that HDL works in the body, and can increase the risk of heart disease.
The variant is found in a specific molecule known as SR-BI. The mutation in SR-BI causes increased levels of HDL and an increased risk of heart disease.
The people studied had levels of HDL greater than 95 milligrams per deciliter (mg/dL). These levels are abnormally high. The researchers found that some of the people in their study did have this rare genetic defect.
Another study found that people who recently had a heart attack and who have both high HDL and high levels of a substance called C-reactive protein were at higher risk of having another cardiac event. C-reactive protein is produced by the liver when inflammation occurs in the body.
A study in Circulation found that a defect in a specific protein known as cholesteryl ester transfer protein (CETP) may also cause abnormally high HDL levels and an increased risk of heart disease. The study was large but only looked at Caucasians. It found that the CETP defect increased heart disease risk in the women but not men.
Furthermore, cholesterol balance may be an important factor to consider, according to a review in Atherosclerosis.
A study mentioned in this review discusses a large group of men and women who had varying HDL levels. They found that those with "extreme" high or low HDL levels had a higher risk of death than those who had more moderate levels.
The best levels, according to this study, are 73 mg/dL in men and 93 mg/dL in women.
The American Heart Association (AHA) recommend all people ages 20 and older get a cholesterol test at least every 4 to 6 years.
On the other hand, the United States Preventative Services Task Force recommend screening for cholesterol disorders starting at the age of 20 years old if risk factors for heart disease are present.
It is not just adults who are being checked for high cholesterol today, however. The American Academy of Pediatrics (AAP) recommend all children between ages 9 and 11 get a cholesterol test. The AAP say this recommendation is due to increasing childhood obesity in the U.S.
Children with risk factors, such as family history of high cholesterol, should be tested between ages 2 and 10 years.
Cholesterol tests measure the amount of cholesterol in mg/dL. Most tests show HDL, LDL, and total (serum) cholesterol. The total cholesterol score is a person's HDL and LDL cholesterol levels and 20 percent of their triglyceride level added together.
The AHA no longer publishes specific cholesterol ranges and say that these numbers are not the final word on heart disease risk. Instead, cholesterol levels are just one of many factors to consider.
A "desirable" cholesterol range, the AHA say, may vary from one person to the next. What is desirable will depend on other elements like triglyceride level, other existing health conditions, lifestyle, and family history of heart disease.
For an idea of where cholesterol numbers should be, the National Heart, Lung, and Blood Institute and National Institutes of Health have published the following cholesterol guidelines. These numbers should be discussed with a doctor to determine overall heart disease risk.
|Total cholesterol level||Category|
|Less than 200 mg/dL||Desirable|
|200-239 mg/dL||Borderline high|
|240 mg/dL and above||High|
|LDL cholesterol level||Category|
|Less than 100 mg/dL||Optimal|
|100-129 mg/dL||Near optimal - above optimal|
|130-159 mg/dL||Borderline high|
|190 mg/dL and above||Very high|
|HDL Cholesterol level||Category|
|Less than 40 mg/dL||Heart disease risk|
|40-59 mg/dL||The higher, the better|
|Greater than 60 mg/dL||Protects against heart disease|
While HDL can be too high, a more common problem is having low HDL and high LDL. The AHA state that heart disease accounts for a third of all deaths in the U.S.
More than 30 million Americans have cholesterol levels that are too high (above 240 mg/dL), according to the CDC. More than 73 million have high LDL levels, and fewer than a third of them are taking steps to reduce it.
Knowing one's cholesterol level and taking steps to reach or maintain ideal levels are the best ways to ensure HDL and LDL levels are healthy.
Other heart disease risk factors should also be considered, such as age, weight, diet and activity level, blood pressure, and lifestyle factors.
To achieve healthy cholesterol levels, experts recommend:
- getting a cholesterol check at least every 5 years, or as recommended by a doctor.
- eating a heart-healthy diet rich in fruits, vegetables, whole grains, and lean protein.
- limiting saturated fats, fried foods, salt, and sweets
- exercising for 30 minutes, four to five times per week
- not smoking
If HDL levels are abnormally high (greater than 90 mg/dL), people should consider tests to look for genetic problems or other heart disease risk factors.
High cholesterol can be caused by genetics. Even people who follow a healthy lifestyle may need additional help to reach healthy levels.
If a doctor prescribes cholesterol medications, these should be taken exactly as directed. In addition, other health conditions, such as diabetes or high blood pressure, should be properly looked after by a healthcare team.
Cholesterol is an important indicator of heart disease risk, and regular checks are important. Although extreme high HDL levels are rare, they can be a cause for concern in some cases.
People with abnormally high HDL or LDL levels may need additional testing and care to control it and to monitor heart health.
Fortunately, high cholesterol is usually a manageable condition that can be controlled with lifestyle changes and medications when needed.