The Causes and Dangers of High Cholesterol

Cholesterol is a waxy substance that your body uses to make many things — like new cells, hormones, digestive fluids, even vitamin D. When most people think of cholesterol, they think of heart disease. But there are different types of cholesterol, and not all are harmful. 

The form of cholesterol that gets the most attention is LDL, or “bad” cholesterol. Having too much LDL cholesterol in your blood can cause plaque to build up in your arteries (atherosclerosis). Over time, this can cause blockages that may lead to heart attack, stroke, peripheral artery disease, and other serious health problems. 

In this article we’ll focus on LDL cholesterol, review the common causes of high levels, and explain why it’s bad for you. We’ll also take a look at HDL, or “good” cholesterol, and explain why it matters.

What causes high cholesterol?

More than 1 in 3 Americans has high cholesterol, or hypercholesterolemia. There are many reasons you may have high cholesterol. Some people inherit it, but this only occurs in 1 in 250 people.  

Some of the more common causes of high cholesterol include:

• Diet (more on this below)

• Excess body fat, especially in the abdominal area

• Smoking

• Lack of exercise

• Low thyroid hormone

• Low testosterone in men

• Menopause

• Diabetes

• Some medications, including certain beta blockers and diuretics

What foods cause high cholesterol?

You can have high cholesterol even if you eat a low-cholesterol diet. That’s because your body makes its own cholesterol from many different parts of the foods you eat. For example, certain fats and processed carbohydrates affect your cholesterol levels.

Limiting these common foods may help to keep your cholesterol levels down:

• Red meat: This includes beef and pork, which are full of saturated fats. These fats raise LDL cholesterol levels. Fattier cuts of meat are especially high in saturated fats. But even lean meats can put you at higher risk for heart disease when compared to a plant-based diet.

• Poultry: Many people assume that eating poultry is better for cholesterol, but it turns out that’s not always the case. One study found similar cholesterol levels when it compared people who ate poultry versus red meat.

• Trans fats: These are banned in the U.S. because they’re harmful to the heart and other organs. But they can still occur in small amounts as partially hydrogenated oils in certain oils. Very small amounts of trans fats occur naturally in beef and dairy products. 

• Tropical oils: This includes palm oil and coconut oil. These are high in saturated fats and raise LDL cholesterol. Processed and fried foods often contain these fats. Consider using olive oil or nut oils instead. 

• Processed carbohydrates: This includes food made with white flour as well as many snack foods, like chips and cookies. They can affect your cholesterol level even when the foods are low in fat. 

• Egg yolks: These contain about 200 mg of cholesterol. For people with heart disease or diabetes, that’s usually the upper daily limit. Most people can enjoy an average of one whole egg daily without much effect on cholesterol. If you want to get the protein from eggs without the cholesterol, egg whites are a great option. 

• Dairy foods: These tend to be naturally higher in cholesterol and saturated fat. But the research is mixed on dairy’s effect on cholesterol. Although butter raises LDL cholesterol, cheese does not seem to have the same effect. And studies have not found a link between high-fat dairy and heart disease. 

You may also be wondering about seafood. Shellfish are often considered to be high in cholesterol. But researchers found that these foods did not raise cholesterol levels. Of course, if you eat fried seafood, the oil to fry them can still be harmful.

Is high cholesterol always bad?

When we talk about cholesterol levels, the total number may be misleading. Your “total cholesterol” is a score that combines your HDL and LDL cholesterol and triglyceride level.

Since this score combines different types of cholesterol, let’s use two examples to unpack what this number means:

1. Person A has a normal total cholesterol level. But when you look at the breakdown, they have low HDL (good) cholesterol and a higher LDL (bad) cholesterol.

2. Person B has high total cholesterol. But they have high HDL (good) cholesterol and low LDL (bad) cholesterol.

Person A is at much higher risk for things like heart disease than Person B, even though Person A has “normal” total cholesterol and Person B has “high” cholesterol.

It’s also helpful to remember that some people with high LDL may never develop blockages in the heart or other organs. When we look at LDL cholesterol, we have to keep the big picture in mind. If you’re young and have no risk factors, then your LDL level may not be as harmful as it is for someone who is over 60 or has other risk factors for heart disease. 

The different types of cholesterol

Your cholesterol profile report from the lab usually breaks down your cholesterol into LDL and HDL numbers. You may also see other numbers on your report, such as VLDL, non-HDL, and triglycerides. Let’s take a closer look.

LDL cholesterol

LDL is the “bad” form of cholesterol. It’s most strongly connected to cholesterol plaque buildup. Although we need a little bit of LDL to keep our cells healthy, too much LDL can be harmful. The more LDL you have, the more likely you’re to develop blockages in the blood vessels that feed the heart, brain, and other organs.

HDL cholesterol

HDL cholesterol helps your body to get rid of bad cholesterol. It does so by taking it to the liver, where it’s flushed out of the body. It may also help reduce inflammation in the artery walls. This  protects you from plaque buildup.  

A high HDL level — over 55 mg/dL — is usually a good sign. In general, people with HDL levels over 55 are less likely to die of heart disease compared with people with HDL under 35. 

Things that you can do to naturally raise HDL include:

• Doing regular exercise about 150 minutes per week, including walking

• Keeping your weight in a healthy range

• Avoiding saturated fats

• Choosing a Mediterranean diet

• Not smoking

Alcohol can also increase HDL. But drinking more than 1 drink daily may increase your likelihood of other health problems. It can also raise triglycerides — a type of fat that circulates in the blood and can be harmful. 

But experts are still trying to understand HDL. For instance, medications that raise HDL have not been found to lower heart attack risk. And scientists no longer believe that a very high HDL is always better. In fact, a recent study of people with heart disease linked HDL levels over 80 mg/dL to a greater risk for heart problems. 

Other studies of people without heart disease have found that an HDL level over 115 may be more dangerous. One of the possible explanations is the relationship of alcohol to HDL, but more research is needed. 

Triglycerides, non-HDL, and VLDL

You may notice a few other numbers listed on your cholesterol test (lipid panel):

• Triglycerides are a type of fat that circulates in the blood. Levels can vary from one day to the next. Starchy foods, fatty foods, sugars, and alcohol can raise triglyceride levels. 

• Non-HDL cholesterol is simply your total cholesterol level minus the HDL. It includes LDL and VLDL.

• VLDL cholesterol is a form of cholesterol that carries triglycerides. Reducing your triglyceride level usually lowers your VLDL, too.

What is a healthy cholesterol level?

When we talk about cholesterol, we are usually most interested in LDL. As we discussed earlier, the total cholesterol can be misleading. That’s why it’s important to look at the different numbers in your panel.

The healthiest cholesterol range for you depends on your unique situation and other medical conditions. For example:

• For people without heart disease, the ideal LDL cholesterol is under 100 mg/dL. 

• If you have heart disease, diabetes, or you’re at high risk for high cholesterol, your provider will probably work with you to get your LDL below 70 mg/dL. This will likely require medications to help. 

• Even if you have no risk factors, you may need treatment for an LDL cholesterol over 160 mg/dL. That’s because numbers in this high range mean you’re more likely to develop problems early in life. If your number falls in this range, your high cholesterol may be due to your genes.

The average LDL in the U.S. is 120 mg/dL, so these ideal ranges might seem low. But a range of 50 to 70 is the norm in active people who are not exposed to a typical Western diet or lifestyle. 

Dangers of high cholesterol 

The higher your LDL, the more likely you are to develop atherosclerosis. This is a condition in which fatty plaque builds up inside your arteries. 

Cholesterol plaque can narrow or block the flow of blood through your arteries. Arteries supply blood, oxygen, and nutrition to our organs and muscles. If you have cholesterol plaque, you’re at higher risk for the following problems: 

• Coronary artery disease, including heart attack and heart failure

• Stroke and TIA (transient ischemic attack)

• Peripheral arterial disease, which can lead to amputation

• Aortic aneurysm, which can be deadly if not caught early

• Renal artery stenosis, which can cause kidney failure and high blood pressure

This is a scary list, but the good news is that these problems are often preventable. 

It’s important to know that high cholesterol does not usually cause symptoms until a problem develops. Some people with genetically high cholesterol may develop xanthoma (yellowish nodules) on the face. But that’s uncommon. 

High cholesterol doesn’t cause dizziness, breathing problems, or even chest pain until there’s a blockage. That’s why the first step is knowing your cholesterol numbers. If you’re a healthy adult with no major issues, that means a blood test every 5 years. People with health conditions may need more frequent testing.

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Written by:

Sarah A. Samaan, MD

Sarah Samaan, MD, FACC, FACP, FASE is a board-certified cardiologist who practiced clinical cardiology for nearly 30 years. She is a member of the American College of Cardiology, the American College of Physicians, and the American Society of Echocardiography.

Edited by:

Katie E. Golden, MD

Katie E. Golden, MD, is a board-certified emergency medicine physician and a medical editor at GoodRx.

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