What Is a Lipid?

Lipids include fats, oils, hormones, and waxes

Lipids are essential to your health, but also may contribute to disease in the body. They are a class of molecules that include hormones, fats, oils, and waxes. Cerumen, the medical term for earwax, is a familiar example. It can give you a visible sense of the thick texture of lipids and why they don't dissolve in water.

It's this quality that makes the lipids you can't see such a problem in the bloodstream. Cholesterol and triglycerides, whether naturally occurring or from the foods you eat, can pose a real threat to your heart health. High levels also are linked to stroke, diabetes, and high blood pressure risk.

This article explains the kinds of lipids and what they do. It will help you understand the risks of high lipid levels, how they are measured, and how to better protect yourself from related illness.

What Does a Lipid Test Measure?

Jessica Olah / Verywell

Types of Lipids

The three primary types of lipids are phospholipids, sterols, and triglycerides. They each play a different role in the body.


Phospholipids make up the outermost layer of cells in the bodies of both animals and humans. They create a protective layer around the cells to help maintain them.

Most people never need to think much about them, but there is a rare autoimmune disorder in which proteins on these lipids are attacked. The protective cell layers are damaged in people with antiphospholipid syndrome (APS).

This disorder is seen more often in people with lupus, especially women. It creates a risk of blood clots, which can lead to heart attacks and strokes, as it attacks blood cells and vessels.APS also may lead to pregnancy complications. Its common name, "sticky blood," is an apt description for what happens inside the body when things go awry with these key lipids.


Sterols are steroids. Cholesterol is the primary steroid in the human body. When cholesterol is processed in the liver, it leads to many critical body functions. They include the making of hormones and vitamin D, as well as bile salts that work on fats so they can be absorbed by the cells.


The fats and oils that you are familiar with in foods are triglycerides. This type of lipid can be saturated or unsaturated, which is part of what makes them liquid or solid at room temperature.

The distinction between a fat and an oil is that oils are unsaturated fats that exist in liquid form at room temperature. Most but not all unsaturated fats meet these criteria and are categorized as oils, including canola oil, corn oil, and olive oil.

Omega fatty acids are essential nutrients that come from foods in the diet. Tuna and salmon are excellent sources, as are some nuts, seeds, and leafy vegetables. These fats reduce inflammation, blood pressure, and triglyceride levels. They reduce the risk of sudden death by a heart attack and prevent blood clots from forming.

Trans fats are fats that have been artificially hydrogenated so that they have a texture needed when making processed foods. Eating foods that contain trans fats can lead to high levels of low-density lipoprotein (LDL), called "the bad cholesterol."

There are two types of proteins that carry cholesterol through the bloodstream: high density lipoprotein (HDL) and low density lipoprotein (LDL). HDL is considered “good” cholesterol, as it absorbs cholesterol and brings it back to the liver, whereas LDL is “bad" cholesterol.

Role of Lipids in the Body

Lipids exist in a variety of foods and play a key role in your diet. They’re synthesized or stored to support the cells and assist in essential processes. Lipids also have many external uses.

In addition to the phospholipid role in protecting cells, lipids are at work in many ways in your body.

Nervous System

Lipids are integral to the nervous system and found in its myelin sheaths. Myelin sheaths are fatty tissue sleeves that protect your nerve cells and increase the conduction of their impulses.

Vitamin Absorption

Lipids make it possible for the body to use vitamins. Lipids produce the fat-soluble vitamins A, D, E and K:

  • Vitamin A is vital for your immune system and vision as well as reproduction.
  • Vitamin D aids in immune health and bone strength.
  • Vitamin E boosts the immune system, helps prevent blood clots, and safeguards cells from free radicals, functioning as an antioxidant.
  • Vitamin K aids in bone health and helps your body heal safely from injuries with the ability to form blood clots.

These are only some of the vital benefits and functions of these important vitamins.

Hormone Production

Lipids are part of the production of certain hormones including estrogen, testosterone, and cortisol. These are needed to control your immune system and metabolism. They also help to balance your water and sodium levels, control inflammation, and help with your body's resilience and ability to heal. These hormones also play a role in the development of sexual characteristics.


The main types of lipids include sterols, like cholesterol, and triglycerides. Both of these types are essential to the body at healthy levels. It's when those levels change, and the amounts are outside of normal ranges, that these lipids may cause serious health issues. Lipids play a number of key roles in the body, including protection of cells and the ability to absorb vitamins.

Other Uses for Lipids

Lipids naturally occur in our bodies. They also are found in the foods we eat, which is why diet is important for keeping lipid levels healthy. But they also have other uses in specific industries.

Skin Care and Cosmetics

Lipids are used in the cosmetics industry to make various skin care and beauty products, such as lotions and creams. Cosmetics and skincare manufacturers add lipids to products for skin moisturization, protection, and repair, and to help skin seem smoother and more radiant.


Pharmaceutical companies make many drug products that contain lipids. The drugs vary widely and include steroids (sterols) used to treat diseases like cancer, and to regulate hormones.

Lipids also are added to certain drugs to help them work better. They may make the drug action last longer, improve drug absorption, or help to target a specific area of the body with the drug.


While lipids are essential for both adequate health and the support of your life, too much can put you at a higher risk of liver disease and heart disease.

Heart diseases are the leading cause of death in the United States and across global causes of death. The World Health Organization estimates 17.9 million people die from heart disease each year, worldwide.

A buildup of low-density lipoprotein (LDL) can cause atherosclerosis (clogging of the arteries), which can lead to a heart attack or stroke. High levels of LDL can be avoided by managing cholesterol and saturated fat consumption, and achieving sufficient levels of high-density lipoprotein (HDL), the “good cholesterol."

Excessive LDL levels are linked with diets rich in fatty meat, fast food, deep-fried foods, milk, cheese, yogurt, butter, and processed foods. HDL-promoting foods include fish, olive oil, vegetables, legumes, nuts, and high-fiber fruits.

Lipid Panels

Your healthcare provider may request a lipid panel as part of a routine annual physical examination or if there’s a reason to suspect certain cardiovascular diseases. Often called a cholesterol test, a lipid panel tests your blood to determine your levels of cholesterol (overall), LDL, HDL, and triglycerides.

The results help your healthcare provider determine your risk for cardiovascular diseases and events including heart attacks and strokes.


The three types of lipids—phospholipids, sterols, and triglycerides—are needed for many essential functions in the body. They offer many health benefits. At the same time, triglycerides and cholesterol may pose health risks if levels of these beneficial lipids are not kept under control. The foods that you eat can add "bad" LDL cholesterol and boost triglycerides, which may cause health issues.

A Word From Verywell

If you're concerned about your lipid levels, contact your healthcare provider. The lipid panel tests will give you the information you need to begin making lifestyle changes, like getting more exercise and changing your diet. Not all lipids are created equal, and high levels of LDL pose a serious risk.

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9 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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