The Dangerous Domino Effect of High Cholesterol

Learn what can happen in the body when your LDL rises—and how that ups your risk of heart attack and stroke.

by Lara DeSanto Health Writer

You got your lab reports and oof, they’re not good. You have high cholesterol, something you know can lead to a heart attack or a stroke. But how’s that possible? After all, you feel completely fine, thank you, and you certainly don’t look like you have a “walking heart attack” sticker on your back. How worried should you be? Understanding what cholesterol actually is, and the troublesome chain of events that take place in the body when levels are increased—known as the cholesterol cascade—can help motivate you to take the necessary steps to take better care of your health.

A Quickie Primer on Cholesterol

So what is cholesterol anyway? Cholesterol is made by your liver. It’s a fat-like substance in your blood, which sounds kind of gross—but it’s not all bad. In fact, some cholesterol plays an important role in keeping you healthy, spurring your body to produce hormones and digest food, according to the Centers for Disease Control and Prevention (CDC). There are two types of cholesterol, and they’re about as different as Dr. Evil and Austin Powers:

  • LDL (low-density lipoprotein) can build up in your arteries, leading to heart disease

  • HDL (high-density lipoprotein) absorbs cholesterol and carries it back to the liver, helping to protect against heart disease

When your doctor tells you your cholesterol is high, they’re usually referring to what’s called your LDL cholesterol—aka “bad” cholesterol. “LDL is a form of cholesterol carried in the bloodstream that when found in high concentrations is associated with an increased risk of heart attack or stroke,” explains Randy Zusman, M.D., cardiologist and director of the division of hypertension at the Massachusetts General Hospital Heart Center in Boston, MA.

The Causes of High LDL Cholesterol

Your LDL can become elevated for a variety of reasons, says James Underberg, M.D., lipid specialist at the Center for the Prevention of Cardiovascular Diseases at NYU Langone Health in New York, NY. Understanding what’s triggering your high number is important because it helps your doctor understand the best way to address it.

Any of these factors (or a combo) can give your LDL an unwanted lift:

  • Genetics. Some people inherit genes from their parents that increase their risk of high cholesterol.

  • Lifestyle. Eating a diet high in cholesterol and saturated fat can increase your LDL levels, according to the National Institutes of Health (NIH). Additionally, not getting enough physical activity can increase cholesterol levels, as can smoking.

  • Certain medications. If you’re taking steroids, blood pressure drugs, and meds for HIV/AIDS, your LDL levels may be increased, per the NIH.

  • Certain medical conditions. Diabetes, kidney disease, and other inflammatory conditions can all contribute to increased LDL cholesterol.

“It’s always important to take a very good history and understand the cause of high cholesterol before moving ahead to doing anything about it,” says Dr. Underberg.

How High LDL Affects Your Body

You know that high LDL cholesterol increases heart attack and stroke risk. But why exactly? To understand that, it helps to learn what’s happening within your cardiovascular system when your LDLs increase.

Quick anatomy lesson: Different parts of your body, like the heart, are supplied blood via tubes called arteries. These make up your circulatory system. And when LDL cholesterol starts to build up in the blood, it can negatively affect the walls of those arteries, says Dr. Underberg. This is the beginning of a slow but dangerous process that could ultimately wreak havoc on your heart or other major organs.

“What drives cholesterol from outside the artery wall to the inside of the artery wall is what we call the gradient. The more [cholesterol] there is outside, the more likely there is to get inside,” he explains. “Imagine you have a door: The more pressure you put on the outside of the door, the more likely the door is to give way.”

That means the higher your LDL levels, the more likely that LDL is to bust through that artery wall. Thankfully, the artery knows how to flush out cholesterol once it penetrates—but if too much is coming in, it can overwhelm the system, Dr. Underberg says. And if the system isn’t working properly, even a normal amount of cholesterol can cause an issue because your body isn’t able to remove it.

This is particularly a problem in people who have certain inflammatory conditions, like diabetes, high blood pressure, rheumatoid arthritis, lupus and inflammatory bowel disease. “All of these, along with obesity and smoking, are risk factors for heart disease because they impact the way cholesterol is managed,” Dr. Underberg explains.

The Worst-Case Scenario

So how does the problem progress from the cardiovascular equivalent of a traffic jam to a health emergency? It starts like this: “When you have too many of these cholesterol particles coming in and an inefficient system for removal, and the system becomes overwhelmed, the cholesterol can accumulate in the artery wall and find its way into white blood cells called macrophage,” Dr. Underberg says. “Those cells become inflamed or irritated, and you start to develop plaque in the artery wall,” which can block the flow of blood in the artery.

Over time, if that plaque destabilizes or ruptures, major problems can arise. What those problems might be depends on the body parts affected. “If the affected artery supplies the heart, then it could result in a heart attack. If that artery supplies the brain, it could result in a stroke,” explains Dr. Zusman. “If the artery supplies the kidneys, it could lead to kidney failure or high blood pressure, and if that artery supplies the GI tract, for example, it could result in gangrene or other GI symptoms.”

Rewrite Your LDL Story With These Smart Moves

It takes time for things to get bad enough to lead to one of those outcomes—which means there’s time to take action (and take action you should!) if your LDL levels start to creep up. “It’s a slow process, but a lot of things can affect it,” says Dr. Underberg. “That’s why lifestyle changes are so important.”

Along with taking any cholesterol medications as prescribed by your doctor, aim to commit to the healthy moves below reduce your cholesterol levels and stay as healthy as possible overall, Underberg says:

  • Don’t smoke.

  • Eat a heart-healthy diet.

  • Maintain a healthy weight.

  • Manage your stress levels.

  • Stay on top of your chronic conditions, like diabetes, high blood pressure, and inflammatory conditions.

The daily tweaks you make starting today can powerfully affect how your own LDL-story goes.

Lara DeSanto
Meet Our Writer
Lara DeSanto

Lara is a former digital editor for HealthCentral, covering Sexual Health, Digestive Health, Head and Neck Cancer, and Gynecologic Cancers. She continues to contribute to HealthCentral while she works towards her masters in marriage and family therapy and art therapy. In a past life, she worked as the patient education editor at the American College of OB-GYNs and as a news writer/editor at