What Is Cholesterol and Why Does Your Body Need It to Function Properly?

It's no secret that cholesterol has a bad rap — get too much of it, and your chances of heart disease rise. However, cholesterol is also very critical for the body to function properly.

For starters, cholesterol is a waxy, fat-like substance found in the foods we eat and produced by the liver, according to Harvard Health Publishing. In fact, your liver produces 80 percent of the cholesterol in your body while the remaining 20 percent comes from your diet. Cholesterol is present in every cell in the body and without it, we wouldn't be able to live. Here are some of the essential tasks cholesterol performs:

• It allows your body to make the hormones estrogen and testosterone.
• It builds cells.
• It makes vitamin D and bile acids.

In short: Cholesterol is essential for your body's health. But if you have too much cholesterol, it can negatively affect your body at the cellular level.

Your liver produces 80 percent of the cholesterol in your body while the remaining 20 percent comes from the foods you eat.

​Read more:​ What Is a Dangerous Cholesterol Level?

Because cholesterol is a fatty substance, aka a lipid, it can't dissolve or mix into the blood. That means it can't travel through the bloodstream on its own. So, the liver packages cholesterol along with other fats into little protein-covered particles called lipoproteins, according to Harvard Health Publishing. Lipoproteins move easily through the body to get cholesterol to wherever it's needed.

Here's what you need to know about the lipoproteins found in your blood:

​LDL cholesterol:​ Low-density lipoproteins (LDL) are the so-called "bad" type of cholesterol, according to the American Heart Association (AHA). While LDL cholesterol isn't bad on its own, if a person has too much LDL, it can join with other substances like calcium and form fatty deposits in the arteries. These deposit buildups, called plaque, make arteries more narrow and rigid, creating a condition called atherosclerosis. Atherosclerosis increases the risk for heart attack, stroke and heart disease.

​Read more:​ Foods That Raise LDL

​HDL cholesterol:​ High-density lipoproteins (HDL) are the "good" kind of cholesterol. In fact, they work to ​prevent​ plaque buildup, according to the AHA. HDL particles travel through the body and pick up excess LDL particles from the bloodstream and arterial walls. HDL then hauls LDL back to the liver for disposal.

​VLDL:​ Very low-density lipoproteins (VLDL) are another type of "bad" cholesterol that can lead to increased plaque, according to the U.S. National Library of Medicine. VLDL is a carrier for triglycerides.

​Triglycerides:​ While they are not a type of cholesterol, triglycerides are a lipid often measured at the same time as cholesterol, and also play a role in your risk of heart disease, according to the U.S. National Library of Medicine. Unlike cholesterol, your body can't make triglycerides on its own — triglycerides come from fatty foods you eat (such as butter and oil) as well as calories you take in and don't immediately use, per the U.S. National Library of Medicine. Triglycerides are stored in fat cells and carried to tissue by VLDL cholesterol.

​Read more:​ What's the Difference Between Triglycerides and Cholesterol?

It's easy to get in the habit of thinking of cholesterol as something that needs to be lowered at all costs. But as you can see, cholesterol is necessary for your body to function properly. The danger is when bad forms of cholesterol skyrocket, as well as when triglycerides are too high.

It's important, therefore, to know not just your ​total​ cholesterol number, but the breakdown of each type of cholesterol in your body. This is measured during a cholesterol test, also referred to as a lipid panel.

A healthy level of triglycerides, which is typically checked at the same time as cholesterol, is less than 150 mg/dL, according to the U.S. National Library of Medicine.

​Read more:​ 5 Factors That Affect Cholesterol Tests

Cholesterol statistics show high cholesterol typically is not accompanied by any symptoms, according to the American Academy of Family Physicians — which is why it's particularly important to get your cholesterol checked. Fortunately, that's an easy task. During a cholesterol test, a blood sample is used to check your cholesterol levels, according to the AHA. For some tests, you may need to fast for nine to 12 hours beforehand.

Adults over age 20 should check their cholesterol every four to six years, recommends the AHA. The Centers for Disease Control and Prevention (CDC) also recommends testing children's cholesterol once pre-puberty (between the ages of nine and 11) and once post-puberty (between the ages of 17 and 21).

Based on your family history — and the cholesterol levels revealed by your lipid panel — your doctor may recommend more frequent cholesterol screenings.

​Read more:​ What's a Healthy Cholesterol Ratio?

As mentioned, the body produces cholesterol in the liver, but it can also get cholesterol from animal-based foods like meat and dairy. Food-derived cholesterol is known as dietary cholesterol and until recently, it was believed that dietary cholesterol played a significant part in causing high blood cholesterol.

But a June 2018 review in the journal ​Nutrients​ concludes that dietary cholesterol does not significantly affect blood cholesterol, which is why the 2015–2020 Dietary Guidelines for Americans removed the recommendations of restricting dietary cholesterol to 300 milligrams per day. Instead, saturated fats, trans fats and refined carbohydrates (such as sugar) have a much greater effect.

​Read more:​ The Truth About High Your Diet Affects Your Cholesterol

The effect of dietary cholesterol on blood cholesterol can vary from person to person but it seems saturated fats have a much more universal effect, Robert H. Eckel, MD, professor of medicine, emeritus, at the University of Colorado, Anschutz Medical Campus, former president of the American Heart Association and president of the American Diabetes Association, tells LIVESTRONG.com.

"Meats, dairy and baked goods all have lots of saturated fats. Saturated fats raise LDL in everyone," says Dr. Eckel. The only exception is eggs.

Eggs, particularly the yolks, are high in cholesterol but low in saturated fats. And while a March 2019 meta-analysis published in ​JAMA​ notes a connection between eating eggs and a higher risk for heart disease and early death, Dr. Eckel says that a person would need to eat a lot of eggs (in the range of three a day) for it to affect blood cholesterol levels.

"If [a person] didn't get any cholesterol via their diet, they would still have lipoproteins. Dietary cholesterol does not increase cholesterol directly. But when the liver sees more dietary cholesterol, it impairs the removal of LDL from the bloodstream," Dr. Eckel says.

Since the jury is still out on whether dietary cholesterol affects blood cholesterol, it's still best to limit or avoid high-cholesterol foods because they usually contain high amounts of saturated fats.

​Read more:​ The 9 Best Cholesterol-Lowering Foods

As mentioned, cholesterol is critical for the body to function but too much cholesterol can cause adverse health effects.

High cholesterol is often caused by lifestyle choices, though it can also be caused by genetics and older age. The most common lifestyle risk factors for high cholesterol levels are poor diet, lack of exercise, obesity and smoking, according to the Mayo Clinic. Poorly managed diabetes is also a risk factor.

If you have high cholesterol levels, lifestyle changes are typically the first line of attack, according to the Mayo Clinic. But if exercise and a healthy diet do not reduce cholesterol levels, medications, such as statins, may be warranted.