9 Things You May Not Know About Cholesterol

Everyone knows that high cholesterol is a health problem. But you may be surprised to learn that cholesterol itself—a waxy, fat-like substance—is essential for important body functions, like making hormones, cell membranes, and certain vitamins.

Cholesterol is produced and regulated by the liver. For many people, problems arise when they eat too many foods that contain cholesterol and ones high in saturated fat (such as red meat and whole-fat dairy products) that, over time, increase the total amount of cholesterol in their body. It then begins to circulate in the bloodstream, building up on the artery walls and forming plaque. This buildup, called atherosclerosis, can cause narrowed blood vessels, increasing the risk of heart disease and stroke.

The health issues caused by atherosclerosis have different names, depending on which arteries (a type of blood vessel) are affected. “When cholesterol plaque is in the heart arteries, we call it ‘coronary artery disease,’” says Yale Medicine cardiologist Antonio Giaimo, MD. “When it’s in the neck arteries, we call it ‘carotid artery disease.’ In the leg and abdominal arteries, we call that ‘peripheral artery disease.’”

Additional problems arise when plaque builds up within the arteries and a piece breaks off, traveling through the bloodstream and lodging in a blood vessel, preventing blood from flowing.

“Those blockages can be sudden—blockages of the heart’s blood vessels are usually what cause heart attacks,” says Yale Medicine cardiologist Ehimen Aneni, MD, MPH. “It’s similar to stroke, which is caused by blockages to blood vessels in the neck or brain.”

To diagnose or prevent these issues, your physician will check your cholesterol regularly to see if it’s too high. If so, lifestyle changes and medications may lower your levels, decreasing your risk of serious health conditions.

Below, Drs. Giaimo and Aneni discuss all things cholesterol, including how to check it and treatment options for high cholesterol.

First, it’s important to know that there are different types of cholesterol. Knowing how much of each type you have is important. To determine this, you may be given a blood test called a lipid panel.

The test measures:

• Low-density lipoprotein (LDL) cholesterol (known casually as “bad” cholesterol), which forms plaque on artery walls.
• High-density lipoprotein (HDL) cholesterol (known casually as “good” cholesterol), which helps the body flush out plaque from the arteries.
• Triglycerides. These fats aren’t cholesterol, but they’re measured in a lipid panel. They are necessary for proper body functioning, but high levels increase the risk of heart attack, stroke, and pancreatitis.
• Total cholesterol. This number is based on your LDL, HDL, and 20% of your triglyceride levels.

There is also something called non-HDL cholesterol, a value derived by subtracting the HDL from total cholesterol. Non-HDL cholesterol includes LDL cholesterol, as well as lesser-known cholesterols that can cause atherosclerosis. Some researchers believe it may be a better indicator of your risk of heart disease, since it covers all of the plaque-causing cholesterols in the blood.

The test for non-HDL cholesterol isn't usually part of screening for your total cholesterol. But if you have high blood pressure, diabetes, or other risk factors for heart disease, your chances of having a heart attack are higher than normal. In these cases, your health provider may calculate your non-HDL cholesterol, too.

Routine lipid panels also don’t measure lipoprotein(a), but some physicians order tests for this because high levels may cause atherosclerosis. Lipoprotein(a) is determined by genetic factors, not diet.

“Lipoprotein(a) only needs to be checked once because the levels don’t change much over the course of a lifetime,” says Dr. Giaimo.

According to the American Academy of Pediatrics, children should have their cholesterol checked between ages 9 and 11 (due to the growing obesity epidemic) and again at 17 (as puberty may affect cholesterol levels).

Certain children should have their cholesterol checked between ages 2 and 10:

• Those with parents or grandparents whose total cholesterol levels are 240 mg/dL or higher
• Those with parents or grandparents who have experienced heart attack, stroke, blocked arteries, or blood vessel diseases at or before age 55 (in men) or 65 (in women)
• Those with high blood pressure, diabetes, obesity, or other risk factors for heart disease
• Those who are adopted or have an unknown family health history. If a child has high cholesterol levels, doctors may check to see if they have an underlying condition that needs to be treated.

In adulthood, starting at age 20, you should get your cholesterol checked every 4-6 years until age 40. Younger people with high cholesterol should be checked every 1-2 years.

At age 40, it is important to begin getting cholesterol checks annually. Patients with heart disease or who take cholesterol-lowering medications may need checks more frequently.

Doctors recommend different levels for different people.

For children and teens (ages 19 and younger):

• Total cholesterol levels under 170 mg/dL
• Non-HDL cholesterol levels under 120 mg/dL
• LDL cholesterol levels under 100 mg/dL
• HDL cholesterol levels of 45 mg/dL or higher

For men ages 20 and older:

• Total cholesterol levels between 125-200 mg/dL
• Non-HDL cholesterol levels under 130 mg/dL
• LDL cholesterol levels under 100 mg/dL
• HDL cholesterol levels of 40 mg/dL or higher

For women ages 20 and older:

• Total cholesterol levels between 125-200 mg/dL
• Non-HDL cholesterol levels under 130 mg/dL
• LDL cholesterol levels under 100 mg/dL
• HDL cholesterol levels of 50 mg/dL or higher

Patients with a history of cardiovascular events, such as heart attack or stroke, and those with high blood pressure should aim for lower numbers. “If you had a heart attack or a stroke, your LDL should be less than 70 mg/dL, and your non-HDL should be less than 100 mg/dL,” Dr. Giaimo says. “There’s also growing evidence that patients who have had a heart attack or stroke and have other risk factors, like high blood pressure, should have an LDL of less than 55 mg/dL.”

Very high HDL levels aren’t protective, either; they are associated with increased heart attack risk, according to recent research.

When total cholesterol levels are between 200-239 mg/dL and LDL levels are between 100-159 mg/dL, patients are at risk of atherosclerosis. Having total cholesterol levels at 240 mg/dL or higher and LDL levels at 160 mg/dL or higher puts patients at a very high risk of developing atherosclerosis.

As many as 1 in 200 people have an inherited condition called familial hypercholesterolemia, which causes an abnormality in how the body processes cholesterol. “That can range from absorbing too much cholesterol from food to making too much cholesterol in your liver—or not being able to clear cholesterol from your bloodstream,” Dr. Giaimo says.

Other difficult-to-identify genetic abnormalities may cause high cholesterol, even if people make lifestyle adjustments to lower their numbers.

“Many of my patients have been hearing from their doctor for years that they need to eat better and exercise more because their cholesterol is too high,” Dr. Giaimo says. “They’re very frustrated because they’ve been doing those things and their cholesterol barely budges.”

People with familial hypercholesterolemia should follow lifestyle changes, but they will also need medication to help lower their cholesterol levels. Many patients with familial forms of high cholesterol need to take more than one type of medication to lower their levels.

The 10-year pooled cohort equation (PCE) is a tool that the American Heart Association and the American College of Cardiology developed in 2013 to help doctors estimate a patient’s 10-year risk of having a heart attack or stroke from atherosclerosis.

The tool takes into consideration a patient’s race and gender, as well as their cholesterol levels, systolic blood pressure levels, diabetes status, and whether or not they smoke. It’s typically offered to patients between the ages of 40 and 79 to help prevent cardiovascular health issues. When patients are found to be at increased risk, doctors recommend lifestyle changes and/or medication.

Calcium scoring is a low-radiation CT scan of the heart that may be offered to patients between the ages of 40 and 70 who are at increased risk of developing heart disease but may not yet meet the criteria for being on cholesterol-lowering medications. It identifies whether a patient has calcified (hardened) cholesterol plaque in the coronary arteries (i.e., those that bring blood to the heart). Cholesterol plaque starts out soft, but the body hardens plaque within the arteries as a protective measure to prevent it from breaking off and causing a heart attack or stroke.

A patient’s score is based on the quantity of calcified cholesterol plaque measured in the coronary arteries, which predicts their risk of a heart attack or stroke.

“You want a score of zero,” Dr. Giaimo says. “That means the risk that you’ll have a heart attack or stroke over the next 10 years is very low. As the calcium score increases, so does the risk.”

Calcium scoring helps identify more patients who should take cholesterol-lowering medications, including those who aren’t identified when assessed with the PCE. Patients with a zero score should be retested every 5-7 years. Those with a score between 1 and 100 should be retested every 3-5 years and may choose to start cholesterol-lowering medications to prevent progression. Patients with a score over 100 should start cholesterol-lowering medications and may not need to be retested if their cholesterol levels respond to treatment.

Doctors typically start by recommending lifestyle changes to help patients improve their cholesterol levels. They’re encouraged to change their diet and get more physical activity.

“We recommend the Mediterranean diet,” Dr. Aneni says. “It’s greens, whole grains, and fruits, fortified with nuts and extra virgin olive oil. The cholesterol comes down nicely, with benefits observed as early as three months, and it reduces the tendency of the blood vessels to inflate. Inflammation can make the cholesterol even more sticky.”

Patients should also do 30 minutes of moderate physical activity, like brisk walking, or 15 minutes of vigorous physical activity, like jogging or playing tennis, every day.

If lifestyle changes don’t lower a patient’s cholesterol, or if the levels are high enough to warrant medication right away, doctors prescribe statins to decrease cholesterol levels.

Statins are medications that help lower LDL cholesterol in the body. The medication prevents an enzyme that the liver needs for the production of LDL cholesterol from doing its job, resulting in lower LDL cholesterol levels. Statins also create a covering over existing plaque in the arteries so that it doesn’t break off, and they prevent more plaque from forming.

“Statins will lower the cholesterol levels in your bloodstream, but what’s not talked about as much is that statins actually help prevent cholesterol plaques that are already in the arteries from rupturing,” Dr. Giaimo says. “That’s one of the main ways that they help prevent heart attack and stroke.”

Healthy lifestyle habits may help people keep their cholesterol levels in a healthy range.

Being more active can help people maintain a healthy weight and decrease their risk of high cholesterol. Eating more plant-based foods helps, too, because animal-based foods often contain cholesterol and saturated fat. And whenever possible, people should try to prepare their own food.

“Much of the food that we purchase in the U.S. has been processed or has cholesterol and added salt,” Dr. Giaimo says. “The more often you prepare healthy food at home, the lower your risk for developing high cholesterol.”