Wondering what those numbers mean for your heart and your health? Here’s what you should know about your blood cholesterol levels, and how to keep them under control.
To understand how cholesterol affects your health, you must first know what cholesterol actually is.
Cholesterol is a waxy substance that your body requires to build cells and manufacture vitamins and other hormones, according to the American Heart Association (AHA).
Your body makes all the cholesterol it needs in your liver. But you can also get cholesterol in the foods you eat. Dietary sources of cholesterol are primarily animal products and include:
For some people, these foods represent a major source for increasing blood cholesterol. Because the typical Western diet is loaded with these foods, rising cholesterol levels have led the way to an epidemic of health problems linked to high cholesterol, says Trejo Gutierrez, MD, a cardiologist with the Mayo Clinic in Jacksonville, Florida.
Though some experts dispute the direct link between high blood cholesterol levels and cardiovascular disease (CVD), major organizations like the National Heart, Lung, and Blood Institute (NHLBI) maintain that high blood cholesterol levels play a role in the development of conditions such as atherosclerosis, carotid artery disease, coronary artery disease, heart attack, stroke, peripheral artery disease, and sudden cardiac arrest.
Types of Cholesterol and How They Work in Your Body
Cholesterol is carried through the circulatory system on two lipoproteins: high-density lipoproteins (HDL), often referred to as “good” cholesterol, and low-density lipoproteins (LDL), also called “bad” cholesterol.
HDL has been labeled “good” cholesterol because it removes LDL cholesterol from the arteries and takes it to the liver, where it can be broken down and removed from the body, according to the AHA.
LDL is termed “bad” cholesterol because when there is too much of it circulating in the blood (more than the good HDL scavengers can scoop up and ferry away), it can eventually build up in the form of plaque on the walls of your arteries. This is called atherosclerosis. Over time, this narrows the arteries and raises the risk for heart attack, stroke, and peripheral artery disease, notes the AHA.
A high level of triglycerides — the most common type of fat in your body — can also lead to fatty buildups in your arteries and increase your risk of heart attack and stroke, if combined with high LDL or low HDL cholesterol levels, per the AHA.
Why Are Some People More Likely to Have High Cholesterol Than Others?
Understanding why some people have high cholesterol numbers and others don’t isn’t as simple as it might seem. For example, while overweight people are more likely to have high cholesterol, thin people can have it as well, notes the AHA.
Here are some factors that affect your cholesterol levels:
A condition called familial hypercholesterolemia (FH) may make some people genetically prone to high levels of bad cholesterol. There are two types of FH: heterozygous, in which a person inherits the abnormal gene from one parent only; and homozygous, in which the person has two copies of the abdominal gene, one from each parent. Homozygous FH is both more rare and more dangerous. People with FH don’t recycle LDL cholesterol as effectively and end up with high levels of this type of cholesterol, making them more prone to atherosclerosis, often starting at far younger ages. About 1 in 200 adults have the FH genetic mutation, according to the AHA. If left untreated, these individuals have a 20 times higher risk of developing heart disease.
If you have a parent, sibling, or child who has FH or who had a heart attack early in life, it’s recommended that you get tested for the condition. (The majority of FH patients need cholesterol-lowering drugs such as a statin to keep their cholesterol numbers in a healthy range.)
While smoking doesn’t directly cause high cholesterol, it is by itself a major proven risk for heart disease and stroke. That risk rises if you also have high LDL cholesterol levels. One reason is that smoking lowers your levels of HDL, helping to diminish or erase that form of cholesterol’s protective effect, according to the AHA.
Quitting smoking has immediate benefits on your heart health. A research review published in the journal
Biomarker Research found that HDL levels increase almost immediately in people who quit smoking.
When it comes to what you eat, the best way to lower your cholesterol is to reduce your intake of saturated fat and trans fat, according to the AHA, which recommends limiting saturated fat to less than 6 percent of daily calories and minimizing the amount of trans fat you eat. This means cutting back on red meat, tropical oils, fried foods, and full-fat dairy.
Instead, opt for low-fat or fat-free dairy products, fruits, vegetables, whole grains, poultry, fish, nuts, and nontropical vegetable oils. Healthier cooking oils include canola, corn, olive, peanut, safflower, soybean, sunflower, vegetable oil, and other specialty oils, notes the AHA. As a general rule, says Dr. Gutierrez, “consume a diet that is based mostly on whole, plant-based foods and is low in saturated and animal fats.”
Getting Tested: What Do Blood Cholesterol Test Results Mean?
The AHA recommends that all Americans over age 20 get their cholesterol levels tested every four to six years. Your doctor may recommend getting your cholesterol tested more frequently in middle age because your overall risk for heart disease starts to rise.
Here’s what the test will reveal:
Total Blood Cholesterol Think of this as your overall “score.” This number is the result of a calculation that adds up HDL and LDL levels, plus 20 percent of your triglyceride level, according to the AHA. Although stated guidelines point to a total cholesterol of below 200 milligrams per decililter (mg/dL) as “desirable” and anything over 239 mg/dL as “high,” this number is less meaningful than it might appear, says Barbara Roberts, MD, a clinical associate professor emerita of medicine at Brown University in Providence, Rhode Island, and former director of the Women’s Cardiac Center at The Miriam Hospital. She adds that what’s important is the ratio of good to bad cholesterol.
HDL Cholesterol You want this number to be higher, as a high HDL level is linked with good heart health. An HDL level of 60 mg/dL or higher appears to be protective against heart disease, notes the Cleveland Clinic. In contrast, a level of less than 40 mg/dL appears to be nonprotective and may be harmful.
LDL Cholesterol An LDL of less than 100 mg/dL is the holy grail; a number 129 mg/dL or lower is also good. A range of 130 to 159 mg/dL is borderline high, 160 to 189 mg/dL is high, and above 189 mg/dL is in the danger zone, per the Cleveland Clinic.
Triglycerides Normal levels of triglycerides vary by age and sex, according to the AHA. Risk factors that can lead to high triglycerides include having diabetes, being overweight or obese, being sedentary, drinking alcohol in excess, and consuming a diet that is high in sugar, processed foods, and saturated fat. A normal level is below 150 mg/dL; if your level is approaching 200 mg/dL, that is borderline high; and anything over 200 mg/dL is high and leaves you at greater risk for cardiovascular disease, per the Cleveland Clinic. A triglyceride level of 500 mg/dL or higher is considered dangerously high.
Facts About Cholesterol-Lowering Medication
If you and your doctor feel it would be wise to lower your cholesterol levels, you may be prescribed a statin drug. Guidelines put out by the AHA and the American College of Cardiology in 2019 say that the decision to start statin therapy should be based on a calculation of your risk for cardiovascular disease over 10 years.
Cholesterol numbers, says Gutierrez, are only part of the picture, “though the most current recommendations say that in the presence of diabetes you should start medication when LDL is higher than 70 mg/dL.”
He also points out that it’s important to first try making lifestyle changes, such as:
Consuming a healthier diet
Getting blood pressure under control
It’s also important to note that those lifestyle changes should not be abandoned just because you’re taking medication.
Statin drugs work in two ways, says Gutierrez. “They block the enzyme that helps you produce cholesterol in the liver, and they activate the receptors for LDL in your liver cells, so that more cholesterol is ‘captured’ from your blood.”
In addition to statin drugs, a new class of cholesterol-lowering drugs called PCSK9 inhibitors was approved by the U.S. Food and Drug Administration (FDA) in 2015 to treat people with familial hypercholesterolemia and other risk factors. PCSK9 inhibitors are monoclonal antibodies that work to inactivate a protein in the liver called proprotein convertase subtilisin-kexin type 9 (PCSK9), reducing the amount of LDL circulating in your body.
Cholesterol and Heart Disease: Understanding the Connection
For years, it had been believed that there’s more or less a straight line between cholesterol and heart disease — but recent research suggests that this relationship may be more complex.
A Minneapolis Heart Foundation study, published in April 2017 in the
Journal of the American Heart Association , found that many people who have heart attacks don’t have high cholesterol. “The link between cholesterol and heart disease is weak,” says Dr. Roberts, who places a large portion of the blame for the persistence of that link on pharmaceutical advertising for statin drugs. “Statins do lower cholesterol levels,” she says, “but atherosclerosis still progresses” due to factors like age, poor diet, smoking, and so on.
In addition, a review of studies of cholesterol and cardiovascular disease published in August 2015 in the
American Journal of Clinical Nutrition found that no rigorous connection could be drawn between dietary cholesterol intake and the risk of CVD.
In contrast, the results of long-term research, published in September 2017 in the journal
Circulation, concluded that statin use in men with high LDL cholesterol who had no other risk factors for heart disease reduced their rates of coronary heart disease death, cardiovascular death, and all-cause mortality by 28 percent over 20 years.
Furthermore, a study of more than 400,000 people published in December 2019 in
The Lancet found a strong link between non-HDL cholesterol and long-term risk of cardiovascular disease.
Still, when it comes to heart health, your biggest risk factor is age, says Roberts.
To keep your risk of high cholesterol as low as possible and your heart as healthy as you can for as long as you can, eat real (unprocessed) food, exercise regularly, don’t smoke, and keep your blood pressure under control.