Triglycerides: Definition, Chemical Structure, Metabolism, Associated Diseases, Industrial Uses, and Simple Ways to Lower Levels

They are the main components of body fat in humans and other animals, as well as vegetable fat.

A triglyceride (TG, triacylglycerol, TAG, or triacylglyceride) is an ester derived from glycerol and three fatty acids (from tri- and glyceride).

They are also present in the blood to allow bi-directional transfer of adipose fat and blood glucose from the liver, and are a major component of human skin oils.

There are many different types of triglycerides, with the main division between saturated and unsaturated types. Saturated fats are “saturated” with hydrogen; all available places where hydrogen atoms can be attached to carbon atoms are occupied.

These have a higher melting point and are more likely to be solid at room temperature. Unsaturated fats have double bonds between some of the carbon atoms, reducing the number of places where hydrogen atoms can bond with carbon atoms.

These have a lower melting point and are more likely to be liquid at room temperature.

Chemical structure

Triglycerides are chemically glycerol fatty acid triesters. Triglycerides are formed by combining glycerol with three fatty acid molecules. Alcohols have a hydroxyl group (HO-).

Organic acids have a carboxyl group (-COOH). Alcohols and organic acids join together to form esters. The glycerol molecule has three hydroxyl groups (HO-). Each fatty acid has a carboxyl group (-COOH).

In triglycerides, the hydroxyl groups of glycerol join the carboxyl groups of the fatty acid to form ester bonds:

  • HOCH2CH (OH) CH2OH + RCO2H + R’CO2H + R «CO2H → RCO2CH2CH (O2CR ‘) CH2CO2R» + 3H2O.

The three fatty acids (RCO2H, R’CO2H, R «CO2H in the above equation) are usually different, but many types of triglycerides are known.

The chain lengths of the fatty acids in naturally occurring triglycerides vary, but most contain 16, 18, or 20 carbon atoms.

Natural fatty acids found in plants and animals are typically made up of even numbers of carbon atoms, reflecting the pathway for their biosynthesis from the two-carbon acetyl CoA block.

Bacteria, however, possess the ability to synthesize branched and foreign chain fatty acids.

As a result, animal fat from ruminants contains odd fatty acids, such as 15, due to the action of bacteria in the rumen. Many fatty acids are unsaturated, some are polyunsaturated (for example, those derived from linoleic acid).

Most natural fats contain a complex mix of individual triglycerides. Because of this, they melt in a wide range of temperatures.

Cocoa butter is unusual in that it is made up of only a few triglycerides, derived from palmitic, oleic, and stearic acids at the 1, 2, and 3 positions of glycerol, respectively.


The simplest triglycerides are those in which all three fatty acids are identical. Their names indicate the fatty acid: stearin derived from stearic acid, palmitin derived from palmitic acid, etc.

These compounds can be obtained in three crystalline forms (polymorphs): α, β and β ‘, the three forms differ in their melting points. .


If the first and third chains R and R ‘are different, then the central carbon atom is a chiral center and, as a result, the triglyceride is chiral.


Pancreatic lipase acts on the ester bond, hydrolyzing the bond and “releasing” the fatty acid. In the triglyceride form, lipids cannot be absorbed by the duodenum.

Fatty acids, monoglycerides (a glycerol, a fatty acid), and some diglycerides are absorbed by the duodenum, once the triglycerides have been broken down.

In the intestine, after the secretion of lipases and bile, triglycerides break down into monoacylglycerol and free fatty acids in a process called lipolysis. They subsequently move into absorbent enterocyte cells that line the intestines.

Triglycerides are rebuilt in enterocytes from their fragments and package together with cholesterol and proteins to form chylomicrons.

These are excreted from the cells and collected by the lymphatic system and transported to the great vessels near the heart before mixing with the blood.

Chylomicrons can be captured by various tissues, releasing triglycerides to be used as an energy source.

Liver cells can synthesize and store triglycerides. When the body needs fatty acids for energy, the hormone glucagon signals the breakdown of triglycerides by hormone-sensitive lipase to release free fatty acids.

As the brain cannot use fatty acids as an energy source (unless it is converted into a ketone).

The glycerol component of triglycerides can be converted to glucose by gluconeogenesis by conversion to dihydroxyacetone phosphate and then to glyceraldehyde 3-phosphate, for brain fuel when broken down.

Fat cells can also break down for that reason, if the needs of the brain exceed those of the body.

Triglycerides cannot cross cell membranes freely. Special enzymes in blood vessel walls called lipoprotein lipases must break down triglycerides into free fatty acids and glycerol. Fatty acids can be taken up by cells through the fatty acid transporter (FAT).

Triglycerides, as major components of very low-density lipoproteins (VLDL) and chylomicrons, play an important role in metabolism as sources of energy and transporters of fats in the diet.

They contain more than twice the energy (approximately 9 kcal / g or 38 kJ / g) than carbohydrates (approximately 4 kcal / g or 17 kJ / g).

Associated diseases

In the human body, high levels of triglycerides in the bloodstream have been linked to atherosclerosis and, by extension, to the risk of heart disease and stroke .

However, the relative negative impact of elevated triglyceride levels compared to that of low-density lipoproteins is still unknown.

The risk may be partly explained by a strong inverse relationship between triglyceride level and high-density lipoprotein cholesterol level.

But the risk is also due to high triglyceride levels that increase the number of small, dense low-density lipoprotein particles.


The National Cholesterol Education Program has established guidelines for triglyceride levels.

These levels are tested after fasting for 8 to 12 hours. Triglyceride levels temporarily stay higher for a period after eating.

The American Heart Association recommends an optimal triglyceride level of 100 mg / dL (1.1 mmol / L) or less to improve heart health.

Lowering triglyceride levels

Weight loss and diet modification are effective first-line lifestyle modifications for hypertriglyceridaemia.

For people with moderate or moderate triglyceride levels, lifestyle changes are recommended that include weight loss, exercise, and diet modification.

This may include restricting carbohydrates (specifically fructose) and fat in the diet and consuming omega-3 fatty acids from algae, nuts, and seeds.

Medications are recommended for people with high triglyceride levels that are not corrected by lifestyle modifications, with fibrates recommended first.

Epanova (omega-3-carboxylic acids) is another prescription medicine used to treat very high levels of triglycerides in the blood.

The decision to treat hypertriglyceridemia with medication depends on the levels and presence of other risk factors for cardiovascular disease. Very high levels that would increase the risk of pancreatitis are treated with a drug from the fibrate class.

Niacin and omega-3 fatty acids, as well as drugs from the statin class can be used together, with statins being the main drug for moderate hypertriglyceridemia when cardiovascular risk reduction is required.

Industrial uses

Flaxseed oil and related oils are important components of useful products used in oil paints (vape) and related coatings. Flaxseed oil is rich in di and triunsaturated fatty acid components, which tend to harden in the presence of oxygen.

This heat-producing hardening process is peculiar to these so-called drying oils. It is caused by a polymerization process that begins with oxygen molecules attacking the carbon backbone.

Triglycerides are also divided into their components through transesterification during the manufacture of biodiesel.

The resulting fatty acid esters can be used as fuel in diesel engines. Glycerin has many uses, such as in the manufacture of food and in the production of pharmaceutical products.


Staining for fatty acids, triglycerides, lipoproteins, and other lipids is done by using lysochromics (fat-soluble dyes).

These colorants can allow the qualification of a certain fat of interest by tinting the material a specific color. Some examples: Sudan IV, Oil Red O and Sudan Black B.

Simple ways to lower your triglycerides

With all the fuss about cholesterol and heart disease, the dangers of having high blood triglycerides are often overlooked.

But, in fact, having high levels of these fats in your bloodstream can be just as dangerous as having high levels of “bad” low-density lipoprotein cholesterol.

High triglyceride levels have been linked to liver and other organ damage, as well as blockage of blood flow to the heart and brain, which can cause a heart attack or stroke.

Very high triglycerides can cause swelling of the pancreas, the organ that produces digestive juices that absorb food, causing pancreatitis.

This can lead to severe abdominal pain , fever, and vomiting. If digestive juices leak out of the pancreas, they can be life threatening.

About 25 percent of adults in the US have elevated blood triglyceride levels, which are classified as levels greater than 200 mg / dl.

High levels are part of a condition called metabolic syndrome that includes high blood pressure, increased fat in the abdomen, and low-density lipoprotein.

The combination of two of these symptoms, along with elevated triglyceride levels, increases the risk of developing type 2 diabetes five times.

Obesity, uncontrolled diabetes, regular alcohol consumption, and a high-calorie diet all contribute to raising triglyceride levels in the blood. Medications may be needed to lower and control these levels, but there are also natural ways to address the condition:

Follow a Low Carb Diet – Like sugar and fat, the extra carbohydrates in your body are converted into triglycerides and stored in fat cells.

Limit alcohol consumption : Since alcohol is high in sugar and calories, even moderate consumption of alcohol can increase blood triglyceride levels by as much as 53 percent, according to research.

Exercise regularly : High-density lipoproteins have an inverse relationship with triglyceride levels. In other words, high levels of high-density lipoprotein can lower triglycerides.

Aerobic exercise, such as walking, jogging, biking, or swimming for at least 30 minutes, five days a week, can increase your high-density lipoprotein levels.

Try Aged Garlic Extract – This natural compound has many beneficial effects on the cardiovascular system, including the ability to lower triglycerides. This is a consistent effect across multiple studies, typically showing a 15-20 percent reduction.

Aged garlic extract slows the progression of coronary plaque and induces regression of soft plaque which is the earliest and most vulnerable cause of heart disease. Other beneficial supplements include fish oil and curcumin.

Eat more fiber : Including more fiber, which is found in fruits, vegetables, grains, nuts, cereals and legumes, in your diet decreases the absorption of fat and sugar in your intestines. This helps reduce the amount of triglycerides that enter your blood.

Avoid trans fats : Studies have shown that people who eat this type of fat that is often added to processed foods to increase their shelf life have significantly higher triglyceride levels than those who eat a high-fat diet unsaturated.

Since a diet high in trans fat can also increase your risk of heart disease, it is wise to limit your consumption of processed, baked, and fried foods.

How do I know if I have high triglycerides?

If you have diabetes, high blood pressure, or other things that make you more prone to heart disease, your doctor may want to monitor your triglyceride levels.

Like cholesterol, triglycerides are a type of fat or lipid in the blood. Too much triglycerides can increase your chances of heart disease or cause sudden pancreatitis.

When might you need a test?

Just as you may unknowingly have high cholesterol, you may not have any symptoms of high triglycerides. Therefore, your doctor will often monitor them regularly, especially if you:

  • Smokes
  • You are overweight or obese.
  • He does not exercise.
  • You have high blood pressure .
  • Had a heart attack or heart disease.
  • You have diabetes or prediabetes, thyroid disease, or kidney disease.

How are triglycerides measured?

A blood test called a lipid panel checks triglyceride and cholesterol levels. Typically, your doctor will ask you to fast or not eat or drink anything other than water for 9 to 12 hours before the test.

Blood will be drawn from a vein in your arm. Some labs offer non-fasting lipid panels or you can prick your blood with your fingertip.

What the results mean

Your triglyceride levels are measured in one of two ways: milligrams per deciliter (mg / dL) or millimoles per liter (mmol / L).

  • Normal : less than 150 mg/dL or less than 1.7 mmol/L.
  • Maximum limit : 150 and 199 mg / dL or 1.8 and 2.2 mmol / L.
  • Alto: 200 a 499 mg/dL o 2.3 a 5.6 mmol/L.
  • Very high : 500 mg / dL or higher or 5.7 mmol / L or higher.

How often should I get tested?

If you are a healthy adult, you should get a lipid profile every 4-6 years. Children should have it done at least once between the ages of 9 and 11, and one more time between 17 and 21.

If you are making changes to your diet or taking a medication for high cholesterol or triglycerides, experts advise you to obtain a lipid profile.