What Is Cholesterol? An Easy-to-Understand Explanation

Your cholesterol levels affect your risk of heart disease and stroke, yet you need this infamous fat to keep your body healthy. So what is cholesterol, and how do we manage it?

what is cholesterol

What is cholesterol? In short, explains the National Institutes of Health, “Cholesterol is a waxy, fat-like substance that’s found in all cells of the body.” Keep yours in check by focusing on a healthy diet; avoid such foods as cold cuts and red meat and limit dairy products.

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You no doubt have heard that high cholesterol is bad for you, but what does that really mean? And exactly what is cholesterol? You may have heard terms like low-density lipoprotein or high-density lipoprotein, but which is good and which is bad? And you may wonder whether you can reduce your risk by adopting a low-fat diet. So let’s clear up some of the confusion!

So What Is Cholesterol?

According to the National Institutes of Health, “Cholesterol is a waxy, fat-like substance that’s found in all cells of the body.” Your body needs cholesterol in order to manufacture hormones (including estrogen and testosterone), bile acids for digesting fat, and vitamin D. It is also an essential part of the structure and protection of every cell in the body.

Where Do We Get Cholesterol?

Less than 20 percent of the cholesterol in your body comes from the food you ingest. The remaining 80 percent is produced by your liver, from the basic building blocks of fats, sugars, and proteins. As anyone who has ever taken a basic chemistry class or cooked a joint of beef will know, fat and water do not mix: The water cells repel the fat cells.

Cholesterol is a fat, so in order for it to travel in the blood stream, it is encased into packages called lipoproteins. Lipoproteins have cholesterol and triglycerides on the inside, surrounded by a protein coating on the outside, which is not repelled by the water in blood.

Types of Lipoproteins

In total there are five types of lipoprotein: chylomicrons; very-low-density lipoprotein (VLDL); intermediate-density lipoprotein (VLDL); and the most well-known duo, low-density lipoprotein (LDL) and high-density lipoprotein (HDL). So as not to get bogged down in complex biochemistry, let’s focus on HDL and LDL here.

  • The bad guys: LDLs. Low-density lipoproteins (LDL) carry cholesterol around the bloodstream, delivering it to tissues that need it. They are formed in the blood when very-low-density and intermediate-density lipoproteins have given up their fatty acids. While they form an important function, research shows that high levels of LDL cause a buildup of cholesterol in the blood vessels—a process known as atherosclerosis, a precursor to coronary heart disease.
  • The good guys: HDLs. High-density lipoproteins (HDL) are made by the liver. Their job is to travel around the body, picking up stray cholesterol and returning it to the liver for processing and excretion.

Imagine two types of trucks driving on the highway. The first type (LDL) is dumping mud on the road. The second type is a road sweeper (HDL) that can clear away the mud. If there are two many mud-dumping trucks and not enough road sweepers, we have a problem—the road highway gets clogged up (atherosclerosis) and the flow of traffic (your blood) slow down.

What Is High Cholesterol?

High cholesterol, or hypercholesterolaemia, is a condition where you have too much LDL and not enough HDL (to mop up the excess cholesterol).

In the early stages there are no symptoms or signs, but it may be detected on a routine blood test. Research has shown that those with hypercholesterolaemia are at higher risk of developing atherosclerosis and coronary artery disease (CAD).

What Is Atherosclerosis?

When your cholesterol level is high for a long period, excess cholesterol attaches to the walls of the arteries, forming “plaques” that harden and narrow your arteries. Blood flow is reduced and less oxygen can get to the heart and other tissue. The results can be:

  • Coronary artery disease (CAD). Sometimes a plaque can rupture (break open) to form a blood clot. Either a blood clot or the narrowing of an artery can become so severe that an area of tissue becomes hypoxic (low oxygen), and over time necrosis (cell death) occurs. This can lead to angina (pain due to hypoxic muscle) or a heart attack (necrosis of heart muscle). If the area of heart muscle that is damaged is large enough, a heart attack may be fatal.
  • Stroke and peripheral artery disease. When either narrowing of the arteries or a clot occurs in an artery in the brain or peripheral tissue (such as the toes or fingers), hypoxia and necrosis may occur. In the brain, this is called a stroke. In peripheral tissue, it can cause pain on exercise and in severe cases gangrene of a toe, finger, hand or foot.
  • Familial hypercholesterolemia (FH). A genetic disorder that causes severe elevations in total cholesterol and LDL cholesterol, familial hypercholesterolemia can occur in up to 1 in 300 people and may lead to early and extensive atherosclerosis, CAD, stroke, and peripheral artery disease. People with FH need to be monitored carefully by a physician.

Improving Your Cholesterol Levels

It makes sense, then, that anything you can do to improve your LDL and HDL ratios will reduce your risk of CAD, stroke, and peripheral artery disease. Here are some strategies to get you started.

  • Know your levels: The first place to start is to get a cholesterol check to give you a baseline measure. See our posts “What Is a Normal Cholesterol Level?” and “Cholesterol Charts: Explaining Your Cholesterol Levels.” If you are diagnosed with high cholesterol, it is essential that you are under the care of an internal medicine doctor or cardiologist, who will monitor and manage your condition.
  • Diet: Reduce your intake of red meat, full-fat dairy products, and processed foods containing saturated or trans-fat. Increase your intake of healthy foods such as leafy greens, berries, and healthy oils (like olive or avocado oil). This will also lower inflammation, which has also been implicated in atherosclerosis. If you want to improve your diet, a Mediterranean-style eating plan is an excellent option.
  • Exercise: Regular exercise, especially aerobic, can improve blood lipid levels, lower blood pressure, and decrease insulin resistance.
  • Stop smoking: Cigarette and cigar smoking increase the risk of atherosclerosis.
  • Maintain a healthy weight: Being overweight increases your LDL levels.
  • Medical treatment: Statins are the mainstay of cholesterol-lowering treatment. However, there is some controversy surrounding statins, as they have significant side effects. Plus, some studies suggest that statins do not reduce mortality. Statins should not be used alone; lifestyle change is also advisable. In very severe cases of familial hypercholesterolemia, lipoprotein apheresis (filtering blood) may be indicated.
  • Cholesterol lowering supplements: Omega-3 fatty acids, turmeric, and oregano oil may all lower cholesterol, although the research is conflicting and results may be unpredictable. Red rice yeast, a natural product, is very similar to statins.

This article was originally published in 2018. It is regularly updated. 

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Leonaura Rhodes, MD

Dr. Leonaura Rhodes is a physician turned author, coach, and freelance medical writer and editor. She has worked for Belvoir Media since 2017 and has authored hundreds of articles on … Read More

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