What causes high cholesterol?

Medically reviewed by Rosanna Sutherby, PharmD on April 10, 2021. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.


Your heart is the hardest working muscle in your body. On average, the human heart beats about 100,000 times a day and is responsible for pumping around 2,000 gallons of blood throughout your entire body each day.

There is a wide range of factors that contribute to your heart and cardiovascular health. Cholesterol is one of the most important health markers, but it is often misunderstood. To learn more about what causes high cholesterol, what you can do to keep it in check, and whether to take a cholesterol test, read on.

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What is cholesterol?

In its physical form, cholesterol is a waxy, fat-like substance. It actually plays a necessary role in a variety of bodily functions. Your body needs cholesterol to synthesize hormones, certain vitamins, and bile (a digestive substance that breaks down fats). It’s even necessary to build basic cells.

Cholesterol comes from two main sources: your liver and the foods that you eat. Your liver actually makes all of the cholesterol that you need. The remainder of your cholesterol comes from animal-based foods, including meat, dairy products, and some cooking oils.

The dangers of high cholesterol

As cholesterol levels increase, your risk of certain health issues, particularly heart disease, stroke, and diabetes, also increases. Cholesterol can combine with fat, calcium, and other substances in your blood to form plaque, a sticky substance that can cling to the walls of your arteries. The buildup of plaque in the arteries is known as atherosclerosis.

Over time, the plaque can harden. This reduces the flexibility in your arteries and constricts or even blocks blood flow. This is known as coronary artery disease, the most common type of heart disease and the leading cause of death in the United States.

A blocked artery can eventually lead to a stroke or heart attack. Coronary artery disease can also weaken the heart muscle and cause heart failure, meaning that the heart is unable to provide blood to all parts of the body. The disease may also contribute to arrhythmias, which refer to changes in normal heart rhythms.

These dangers become even more prominent if you have other risk factors, like smoking, high blood pressure, and diabetes.

Understanding HDL and LDL cholesterol

The true complexity of cholesterol is that it comes in two forms, and your health depends on a careful balance between the two.

Cholesterol is carried through the blood on a type of protein called lipoprotein. Cholesterol takes two different forms based on these lipoproteins. Low-density lipoprotein (LDL) makes up most of the cholesterol in your body. It is considered “bad” cholesterol because high levels of LDL cholesterol contribute to the buildup of plaque and an increased risk of heart disease. Some experts also identify VLDL or very-low-density lipoprotein. This can also contribute to the formation of plaque in the arteries, but VLDL mainly carries triglycerides, not cholesterol.

High-density lipoprotein (HDL) is considered the “good” cholesterol. HDL cholesterol absorbs cholesterol in the blood, bringing it to the liver where it gets broken down and flushed from the body. However, HDL cannot completely neutralize LDL. HDL eliminates about one-third to one-fourth of blood cholesterol. Still, high levels of HDL can reduce your risk of heart disease.

“Good” and “bad” are relative descriptors. Ideally, you should have high HDL cholesterol and low LDL cholesterol. Usually when physicians and other experts refer to “high cholesterol,” they mean high LDL cholesterol.

The causes of high cholesterol

A high cholesterol level can be caused by a wide range of factors. Some factors can’t actually be changed much. For example, some people may inherit high cholesterol. This is known as familial hypercholesterolemia (FH). The severity of this condition can vary, though it is linked to the duration and concentration of LDL cholesterol in the blood. In its most dangerous form, FH can potentially cause premature atherosclerotic heart disease.

Related: What are the symptoms of high cholesterol?

Most other non-hereditary causes of high cholesterol come down to lifestyle. The most prominent include:

Unhealthy eating

Your daily diet has the most significant effect on your cholesterol. The two most prominent contributors to high cholesterol are trans fats and saturated fats. Naturally occurring trans fats are made in the guts of certain animals and can often be found in foods made from these animals. Meats and certain dairy products contain small amounts of trans fats.

The main trans fats to watch out for are artificial trans fats. These are industrially processed and comprise liquid vegetable oils with added hydrogen, which makes them solid at room temperature. They are easy to use and have a long shelf life, making them common in restaurants and fast-food chains. Trans fats also happen to increase your LDL cholesterol while reducing your HDL cholesterol. Regularly consuming large amounts of trans fats can increase your risk of heart disease and stroke.

Saturated fats are also considered bad for your cholesterol. Similar to trans fats, saturated fats are typically solid at room temperature, and they can contribute to high cholesterol. Saturated fats are commonly found in red meat, lard, cheese, and dairy products made from whole milk. While saturated fats aren’t as unhealthy as trans fats, consider limiting your saturated fat consumption. The AHA recommends just 5 to 6 percent of your daily calories come from saturated fats.

Wondering what to eat on a low cholesterol diet? Small amounts of any singular food likely won’t have dramatic effects, but if you are concerned about achieving lower cholesterol levels, consider cutting down on foods rich in trans fats and saturated fats, especially fried foods and processed meats. Focus on a healthy diet that contains a lot of fruits and vegetables, lean sources of protein, and whole grains. And if you are interested in learning specifically about what are the worst foods for high cholesterol, we’ve written about that topic too.

A lack of physical activity

Exercise is good for nearly every component of your health, and cholesterol is no exception. A more sedentary lifestyle has been shown to reduce your HDL cholesterol levels while increasing your LDL cholesterol levels. Sedentary lifestyles are also frequently associated with a poor diet and bad health habits in general.

The good news is that you don’t need a lot of physical activity to see results. Just 60 minutes of moderate-intensity exercise per week may contribute to significant benefits to HDL. Find a sport or activity that you enjoy and can sustain on a regular basis.

Smoking and vaping

If you needed another excuse to quit smoking, your cholesterol might be it. Smoking cigarettes and vaping may increase your LDL cholesterol while lowering your HDL cholesterol levels. Cigarette smoking also causes permanent damage to your heart and blood vessels, allowing fat deposits to build up easier. If you already have cholesterol problems, smoking can significantly increase your risk of coronary heart disease, and it can compound other risk factors like high blood pressure and diabetes.

If you are concerned about your cholesterol or have a family history of high cholesterol, consult your doctor to determine the best ways to keep your cholesterol and triglyceride levels in check. One of the best things you can do is to know your own cholesterol numbers. If you don’t want to get tested in your doctor’s office, consider the Everlywell Cholesterol and Lipids Test. This convenient cholesterol screening allows you to collect a blood sample at home and receive accurate information about your HDL, LDL, and total cholesterol levels, as well as your triglyceride levels. Every test comes with a telehealth consultation to go over your results and provide guidance for further steps toward better personal health.

Everlywell makes lab testing easy and convenient with at-home collection and digital results in days. Learn More