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.
When high
cholesterol is good
HDL cholesterol may remove the LDL
cholesterol that can contribute to the clogging of arteries.
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.
HDL: Is
higher always better?
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.
Finding
the right balance
Cholesterol tests will measure a
persons HDL, LDL, and total (serum) cholesterol.
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 Instituteand 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
|
160-189 mg/dL
|
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
|
Healthy
ways to achieve high HDL
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:
A diet rich in vegetables, fruits,
lean proteins, and whole grains may help people to achieve healthy cholesterol
levels.
·
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.
Outlook
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.
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