Published 16th January 2023

What are triglycerides, and why do you need them?

Triglycerides have a bad reputation. This is because high levels of triglycerides in your blood are associated with poor health outcomes, such as heart disease. 

However, like cholesterol, triglycerides are essential for your body to work. They just need to be present in the right amounts. 

In this article, we’ll explain what triglycerides are and why they’re such fascinating and important compounds.

First up, the basics.

What are triglycerides?

Triglycerides are the most common form of fat in your body.

To get to grips with them, we spoke with ZOE’s chief scientist, Dr. Sarah Berry, who’s spent decades studying fats and lipids.

Triglycerides are a diverse group of chemicals with a simple structure: Three fatty acids connected to a single glycerol “backbone.”

As Sarah explains, “Triglycerides differ according to the mixture of fatty acids they contain.” And these fatty acids differ according to three key features:

  1. how long they are

  2. how many double bonds they have

  3. how the atoms are arranged around the double bond

“These three differences,” she explains, “determine the physical properties of the fat. For instance, their melting point and whether they’re liquid or solid at room temperature. They also determine the health properties of the food.”

Double bonds are a type of strong chemical bond between two atoms.

You may have heard of saturated, monounsaturated, and polyunsaturated fats. The names refer to how many double bonds they have in their structures:

  • saturated = no double bonds

  • monounsaturated = one double bond

  • polyunsaturated = two or more double bonds

There are at least 20 types of fatty acids in food, including: 

  • Omegas 3 and 6: These are in oily fish, seeds, and nuts.

  • Oleic acid: This is in olive oil and all seed oils.

  • Palmitic acid: This is in palm oil.

  • Stearic acid: This is mostly in animal fat and tropical oils.

  • Lauric acid: This is mostly in palm kernel and coconut oil.

Because each molecule of triglyceride can be formed from more than one type of fatty acid, they’re an incredibly varied bunch. 

To give you an idea of their variety, below are the structures of the main triglycerides in olive oil:

  • glycerol backbone + oleic acid + oleic acid + oleic acid

  • glycerol backbone + palmitic acid + oleic acid + oleic acid

  • glycerol backbone + oleic acid + oleic acid + linoleic acid

  • glycerol backbone + palmitic acid + oleic acid + linoleic acid

  • glycerol backbone + stearic acid + oleic acid + oleic acid

Which fatty acids are attached to the glycerol backbone determines the properties of the triglyceride. 

For instance, triglycerides containing unsaturated fatty acids tend to be better for you than triglycerides that contain saturated fatty acids. 

And as a general rule, animal fats contain saturated fats, whereas fish and plant fats are generally unsaturated.

Triglycerides: Where from, where to?

We consume triglycerides in fatty foods — more than 95% of the fat you eat is in the form of triglycerides.

And we usually refer to them as “fats” and “oils.” Fats are solid at room temperature, whereas oils are liquid at room temperature.

When you consume foods containing triglycerides, your enzymes break them down. 

As they make their way through your gut wall, they’re reformed back into triglycerides. This seems like a waste of energy, but they need to be dismantled to make it through the lining of your gut.

Next, they enter your bloodstream in packages called chylomicrons. Once there, they travel to your muscles and are broken down to provide energy or get stored in fat cells. And some head to your liver.

Not only from food

Because triglycerides are an important energy source, your liver produces them almost constantly. It packages them into very-low-density lipoprotein (VLDL) particles, which are very similar to chylomicrons.

Once the triglycerides are removed, VLDL particles become low-density lipoprotein (LDL) cholesterol. This is also known as “bad” cholesterol.

If VLDL or LDL are present at high levels, they can contribute to atherosclerosis — a buildup of plaque in your arteries linked to heart disease.

The benefits of triglycerides

High levels of triglycerides in your blood are associated with an increased risk of developing heart conditions. Still, we couldn’t survive without triglycerides.

So, what important jobs do they have? Sarah outlined three wide-ranging benefits.

1. Energy-dense nutrients

“Triglycerides are packed with energy — 9 calories per gram, compared with 4 calories per gram for protein and 3.75 calories per gram for carbs,” explains Sarah. 

Although being energy-dense has “traditionally been seen as negative,” it’s incredibly important for some populations. These include newborns, some older adults, and people with certain health conditions.

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2. They make food taste good

Sarah believes that this is often overlooked: “What’s the point of eating something that tastes like crap just because it’s healthy?”

Triglycerides carry much of the flavor in food. They also provide that creamy texture we all know and love.

This is why low-fat cheese, for example, doesn’t taste as good or feel as good in your mouth as the full-fat version.

“If you take a steak that has marbling and compare it with a steak that contains no fat, there’s a huge difference in taste,” Sarah noted. “And that’s because the flavor of the steak is mostly carried by the fat.”

3. Essential fatty acids

As you might remember from earlier, triglycerides consist of a glycerol backbone and three fatty acid molecules. 

Some triglycerides contain essential fatty acids. According to Sarah, “This is the most important reason we need to consume triglycerides.”

Your body can't make omega 3 and omega 6 fatty acids. This is why they're “essential” — you need to take them in through your diet. 

Omega 3s and 6s include linoleic acid and alpha-linolenic acid. 

As Sarah tells us, these support various processes, including “brain function, vision, maintenance of skin, and immune function.”

In your body, linoleic acid and alpha-linolenic acid can be converted into the very-long-chain fatty acids eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and arachadonic acid (AA).

These fatty acids play a variety of important roles. For instance, they protect heart health, reduce cancer risk, damp down inflammation, and may even have mental health benefits.

EPA, DHA, and AA also produce a group of chemicals called eicosanoids. And these chemicals are vital, too. 

According to Sarah, among other things, eicosanoids “play important roles in vasodilation, clotting, immune function, and inflammation.”

They also help regulate kidney, gut, and cardiovascular functions.

What if you have too much?

Triglycerides are essential, but when levels are too high in your blood, they increase the risk of developing cardiovascular diseases.

There are many reasons why levels of triglycerides in your blood might be high, including:

  • certain genetic conditions

  • abdominal obesity

  • a diet high in refined carbohydrates

  • alcohol consumption

  • medical conditions, such as gout and kidney disease

  • some drugs, like steroids, retrovirals, and oral estrogen therapy

If you’re concerned about your levels, make sure to speak with your doctor. For more information, we have a guide to reducing blood triglycerides.

The take-home message

Triglycerides are a varied group of crucial compounds. They provide energy and make food taste better. 

Once triglycerides are broken down in your body, some of the free fatty acids have important biological roles.

But not all triglycerides are equal. Consuming triglycerides that contain certain saturated fatty acids are linked to poorer health outcomes, whereas those that contain unsaturated fatty acids tend to be better for your health.

Still, to support your health, it's more important to think about your overall dietary pattern, rather than focusing on single nutrients.

For instance, cheese and butter have similar amounts of triglycerides, but because of their food matrix — their structures and the other compounds they contain — cheese and butter have different health effects.

To summarize, “triglycerides” shouldn’t be a bad word. But, as with most things in life, it’s possible to have too much of a good thing.

Sources

Dietary fatty acids. American Family Physician. (2009). https://www.aafp.org/pubs/afp/issues/2009/0815/p345.html 

Esterified eicosanoids: Generation, characterization and function. Biochimica et Biophysica Acta (BBA) - Biomembranes. (2012). https://www.sciencedirect.com/science/article/pii/S0005273611004408 

High blood triglycerides. (2022). https://www.nhlbi.nih.gov/health/high-blood-triglycerides 

Lipid metabolism. (n.d.). https://open.oregonstate.education/aandp/chapter/24-3-lipid-metabolism/ 

Lipids. (2020). https://open.maricopa.edu/nutritionessentials/chapter/lipids/ 

Myelin fat facts: An overview of lipids and fatty acid metabolism. Cells. (2020). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7226731/ 

Olive oil. (2003). https://www.sciencedirect.com/topics/nursing-and-health-professions/lipid-composition 

Triglycerides. (n.d.). https://www.heartuk.org.uk/cholesterol/triglycerides 

Triglycerides and heart disease. Arteriosclerosis, Thrombosis, and Vascular Biology. (2011). https://www.ahajournals.org/doi/full/10.1161/ATVBAHA.111.226100

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