What are triglycerides?

What are triglycerides: a review of basic chemistry

Do not worry; I will not be talking “chemistry” here. I will simply explain the basic concept of what triglycerides are made of. I will use plain simple English so that anyone with no prior knowledge of chemistry can understand what triglycerides are. Simply speaking, triglycerides are fats, plain and simple. They are household substances present everywhere. Here are some examples of triglycerides you can find in the grocery store and kitchen.

What are triglycerides? simply fats

Triglycerides are called “fat” when they are solid and called “oil” when they are liquid. Animal fat, olive oil, corn oil, butter, whale oil, fish oil, belly fat Chemically, the main component of all these substances is triglycerides.

Why are all these triglycerides so different? They are all made out of different components. Basically they are different triglycerides. The only common component in all the triglycerides is glycerol. It is also a household substance that you may have seen or used. Here is a picture of a beaker of glycerol.

Triglycerides from glycerin

Commercially, it is called glycerin. Chemically, the correct name of Glycerin is Glycerol.

So, what are triglycerides made of? You do not need any sophisticated knowledge of chemistry to understand what triglycerides are made of. It is very simple. Just remember “Tri” and “Glycerin”. It is made up of three fatty acids and one glycerol.

 
Fatty acid 1Fatty acid 2Fatty acid 3 + Glycerine = Triglycerides

So, what are fatty acids? Fatty acids are the basic components of any fat. What fatty acid that particular molecule of triglyceride is made up of, is what makes it different from any other triglyceride. Each fatty acid in any particular triglyceride can have a unique structure. In, essence, a fatty acid is simply an organic compound made up of carbon, hydrogen and oxygen. The structure and number of oxygen molecules in any fatty acid is the same. It is the number and layout of carbon and hydrogen molecules that give each fatty acid its unique property. The three unique fatty acids present in any molecule of a triglyceride give that particular triglyceride a unique property.

Fatty acid=2 oxygen + x-carbon+ y-hydrogen,

where x and y are different for each unique fatty acid .

In summary, what are triglycerides? Triglycerides are fats, made up of one molecule of glycerin and three molecules of unique fatty acid.

What are triglycerides: a review of fat digestion and absorption

Triglycerides are important in digestion and absorption of fat and related compounds in your digestive tract. The triglycerides in your food cannot enter your blood directly without processing. Your digestive enzymes break the triglycerides down into smaller parts.

Triglycedide breakdown in intestine

As you can see, this breakdown results in free fatty acid and 2-mono-glycerides. If the free fatty acid released from the breakdown of triglyceride in food has less than 12 carbons, it is directly absorbed into the blood. From there, it is taken directly to your liver for processing.

If the fatty acid released has more than 12 carbons, it is too large for direct absorption. It has to be packaged into a special ball. The cells in your small intestine do this actively. They take those fatty acids and the 2 –mono-glycerides and combine them back into triglycerides and package them with cholesterol and special protein into a package called “chylomicron”.

Triglyceride packaged into lipoprotein

These packages eventually make their way into your blood. Triglycerides are always carried inside one of these kinds of packages because they do not dissolve in blood. This should mot come as a surprise to you because you already know that triglycerides are basically fat. You know fat and water do not mix. To make triglycerides soluble in water, it has to be packages carefully. Your body makes these packages in a way that the non-water soluble fat is inside the package and does not come in direct contact with water. On the outside, these packages are coated with water-soluble proteins. These proteins are called Apo proteins and these packages are called lipoproteins.

These names may sound very strange and unfamiliar to you but you will soon find that these packages are what make your cholesterol good or bad. When we talk about good cholesterol and bad cholesterol, we are mainly talking about what kind of package that cholesterol is packed in.

Here is brief review of the these terms:

  1. Apo-protein: the protein that encloses fat (triglyceride) and cholesterol to make them soluble in water
  2. Lipo-protein: the whole package of protein, fat and cholesterol. The package is what makes cholesterol good or bad
  3. Chylomicron: A kind of, Apo-protein fat and cholesterol package that carries triglycerides out of your intestine

We do not hear much about Chylomicron because it is not one of the packages that is usually measures when you get your cholesterol checked. This package only exists in your blood to transport triglyceride and cholesterol out of your intensities. Therefore, it only exists in blood after you eat. There are no Chylomicrons in blood when you get your cholesterol checked after an overnight fast. That is exactly why they usually want to you not eat anything in the morning before you get your cholesterol checked.

These particular packages (Chylomicrons) carry triglyceride absorbed from your intestine to three different places:

  1. Fat cells in your body
  2. Muscle cells in your active muscles
  3. Liver

The fat cells open these packages and dissolve them to use the fatty acid again . Muscle cells open these packages and burn the fat as fuel. We will talk about what liver does with these packages in the next section because it is very important.

What are triglycerides and what liver does with them?

Triglycerides in liver may be brand new product manufactured from scratch or could be simply repackaged product made from the package arriving from intestine. When liver opens the package arriving from intestine (Chylomicron), it dissolves it completely. It also breaks down the triglycerides into fatty acids. The fate of these fatty acids will be the same as that of the fatty acid made in liver from scratch.

Your liver can manufacture fatty acids from scratch. You do not have to eat fatty food to have fat inside your body. If you eat more carbohydrate than you can burn, liver weaves those carbohydrate molecules together and manufactures fatty acids from scratch.

Before I explain what liver does with these fatty acids, I want to point out an interesting practical implication of what we just learned so far. We learned that the fat in out food gets packaged out and sent to muscle, fat or liver. If you are active and your muscles are energy hungry, they take up a big chunk of the fat and burn them. If you are sedentary and your liver is already full of fatty acid, your fat cells takes up most of the package and you build up belly fat. This is one of the ways you can build fat deposit in your body. However, you do not need to eat fat to get fat, as you will soon discover.

Your liver has the capability to turn carbohydrate into fatty acid but it also has the capability to break down fatty acid into carbohydrate. Your liver essentially works this based on supply and demand. If your body is active and asking for more fuel, liver breaks down fatty acid and releases them as glucose in the blood. Your muscles then use this glucose as fuel. If you body gets more carbohydrate than it needs, your liver takes up the glucose from your blood and uses it to make fatty acid. Now, you can see that fat deposit in your body depends on how much total calories you eat and how much total calories you burn. It does not depend on how much fat you eat. You don’t need to eat fat to get fat.

triglyceride transport in liver

What does liver do with the rest of the fatty acid? It packages them and sends them out. The process is similar to what your intestine did but the packaging is different. Liver uses different kind of Apo-protein than the intestines. Liver packs the fatty acid and cholesterol using this protein to make the package of Lipo-protein. This Lipo protein is called VLDL. Yes, the LDL in VLDL is the LDL that we all recognize as the bad cholesterol. VLDL simply means Very Low Density Lipo-protein. This package, VLDL, is the precursor to the infamous bad cholesterol LDL. LDL simply means Low Density Lipo-protein. VLDLs get out of the liver and circulate throughout the body supplying triglyceride to any body organ that needs it. The body organs dissolve the triglycerides in VLDL and take them up as fatty acids and use them as needed. When enough triglyceride is used up, the density of VLDL gets higher. Cholesterol is heavier than triglyceride. VLDL is made of protein, triglycerides and cholesterol. When the proportion of triglycerides goes down, the density of VLDL goes up and it becomes LDL.

The main function of LDL is to deposit cholesterol in body organs that needs them. It is the bad cholesterol because it promotes the deposition of cholesterol into cells. It can deposit cholesterol into your arteries when there are other risk factors into play. Cholesterol itself is not a bad substance. It is one of the most important raw materials needed for certain organs to make vital hormones and other substances. For example, you testis cannot make testosterone if it does not get cholesterol.

Cholesterol is so essential that your liver makes it from scratch everyday. Your liver can also get rid of used up or excess cholesterol by converting them into bile. Liver then excretes that bile into your intestine. You do not necessarily get high cholesterol by eating diet high in cholesterol. The problem is usually in the packaging and transport of cholesterol. LDL is the bad guy because it can take cholesterol to where it is not needed and cause problems.

What are triglycerides: how excess triglycerides are sent back to your liver

The triglycerides in your fat tissue are there to be used as fuel when needed. When your energy expenditure is not met by your calorie intake, your body signals your fat cells to release their reserve of triglycerides. In response, your fat cells dissolve the triglycerides into fatty acids and tag them with proteins. They are then released into your blood. These are free fatty acids, not triglycerides. They can be taken up and used as fuel in different organs. They can also be taken back to liver. When fatty acids are back in the liver, their fate is again decided by your liver based on your body’s needs.

This essentially sums up what triglycerides are and how they are transported and used in the body. Before I discuss the potential harmful role of high levels of triglycerides, I want to briefly talk about good cholesterol. Although good cholesterol does not have much role in the metabolism of triglycerides, I am sure you are curious about them. It also does not feel right to not talk about good cholesterol after taking about bad cholesterol.

As you may have guessed, good cholesterol is not actually cholesterol. It is the package in which cholesterol is packaged. The HDL or high-density lipoprotein is the cholesterol package that picks up cholesterol from different parts of your body and returns them to your liver. HDLs are the good guys because they essentially clean up the mess left by LDLs. HDLs promote picking up cholesterol from your body when it is not needed. The Apo-protein for making HDL package is made by your liver. However, the assembly of the actual package is complex and occurs in different parts of the body. While making the package the Apo-protein destined to make HDL picks up cholesterol from different places. It also picks up cholesterol from chylomicrons if there is excess cholesterol in it.

When you eat a diet high in cholesterol, that cholesterol is packaged in Chylomicrons along with the triglycerides. The HDL Apo-protein picks them up and prevent them from getting where they are not needed. This dietary cholesterol eventually goes to your liver where its fate is decided based on what your body needs at that time. If your organs need cholesterol to make hormones, liver sends them out with LDL. If they don’t, liver turns them into bile.

Now you understand why HDL is the protective package. It not only promotes removal of cholesterol from tissues but also helps with safe handling of cholesterol in your diet.

What are triglycerides: the potential harmful effects

Just like cholesterol, triglycerides are not harmful substances to begin with. It is the handling and metabolism of triglycerides that has the potential to cause problems. When you get your cholesterol checked, you see numbers for total cholesterol, HDL-the good cholesterol, LDL-the bad cholesterol and a separate number for triglycerides. As you now understand, triglycerides are not cholesterol. It is checked along with cholesterol when your doctor orders a lipid panel. Cholesterol and triglycerides are both lipids, which is another word for fat-like substance.

High levels of triglycerides have been associated with increased risk of plaque formation in your arteries but it is still not clear if they are the cause of those plaques. Some researchers believe that the association is not causative. They think the same defect in your body that causes your triglycerides to get high in the first place is the cause of actual plaque formation. In other words, they think something else causes both plaques and high triglycerides. There is a lot of controversy and conflicting opinion on this topic even among experts. However, recent trend is to think of high triglycerides as a part of the bigger problem and find out what may have caused it. Even the latest guidelines from American Heart Association (AHA) says that if your triglyceride level is higher than 500, your doctor needs to first investigate what might have caused the elevation before simply starting medication to lower it down. On the actual paper, it lists a few possible causes of high triglyceride your doctor needs to think about.

Here are a few of them:

1. Excessive weight gain,

2. Very low fat diets,

3. High intake of refined carbohydrates,

4. Excessive alcohol intake

5. Certain medications

6. Certain kidney problems

7. Uncontrolled Diabetes

8. Thyroid problems

9. Obesity

The one interesting point on the list is about very low fat diet. That may sound surprising but when we look at how our body handles triglycerides, it makes sense. We saw that liver makes triglycerides when our food does not have enough fat. Very low fat diet may stimulate liver to make excessive amount of triglycerides. Also, very low fat diet is usually associated with increased proportion of carbohydrates. When liver gets the excessive carbs, it has to covert them to triglycerides and send them out with VLDL. This can raise your triglycerides.
Overall, triglycerides may play a role in causing plaques in your arteries but they usually do so in collaboration with high LDL or bad cholesterol. If both bad cholesterol and triglycerides are elevated, you need to focus on bad cholesterol (LDL) first and then address the high triglyceride problem. Recent recommendation from many experts is to look at the overall risk of heart disease before making treatment decisions. There is less focus on the numbers than on the overall risk profile.

What are triglyceride levels and how they are measured?

In the United States, the unit frequently used for measurement of triglycerides is mg/dl. That means milligrams per deciliter. A milligram is a one-thousandth of a gram. A deciliter is one tenth of a liter. If your triglyceride, level is reported as 100mg/dl, you have 1 grams (100 x 10 divided by 1000) of triglyceride in every liter of your blood. In US customary units, that translates to about 1/8th of an ounce of triglycerides in a gallon of blood (0.035 divided by 0.264). Since you have about 4/5 of a gallon of blood in your body, a triglyceride level of 100mg/dl also means that you have about 1/10th of an ounce of fat (4/5 times 1/8) running in your body.

From our calculation you see that every 100mg/dl of your triglyceride number corresponds to about 1/10 of an ounce of fat (triglyceride) flowing in your blood. This will help you imagine the amount of fat running in your blood when we talk about specific blood triglyceride levels.

What are triglycerides levels in a normal people? Well, normal is a relative term here. The exact levels of triglycerides vary widely in the general population. Here is the distribution of fasting triglycerides level in the United States based on the latest publish data:

  • People with triglyceride level of 1000mg/dl or more: 0.4%
  • People with triglyceride level of 500mg/dl or more: 1.7% People with triglyceride level of 200mg/dl or more: 18%
  • People with triglyceride level of 150mg/dl or more: 33%

There is no valid, proven, universally acceptable and useful way to classify triglyceride levels into different categories.

Here is an empiric classification used by many authors:

  • Normal fasting triglyceride level: less than 150mg/dl
  • Borderline high fasting triglyceride level: 150-199mg/dl
  • High fasting triglyceride level: 200-499 mg/dl
  • Very high fasting triglyceride level: greater than 500mg/dl

However, this classification is not very useful and gives you false impression about the significance of high fasting blood triglyceride level. I have used “fasting “ level in all discussion related to triglyceride levels because triglyceride levels can vary greatly after a meal. As you remember, fat in your food is carried by the chylomicrons from your stomach into the blood. The triglyceride in chylomicrons can fluctuate based on what kind of meal you had. We do not want to measure this triglyceride. We only want to measure the triglyceride that liver sends out in the VLDL packages because that level is relatively stable in a person.

A more useful classification of high triglyceride is as follows:



  • First category: Serum triglyceride between 150-500mg/dl
  • Second category: Serum triglyceride between 501-1000mg/dl 3.
  • Third category: Serum triglyceride greater than 1000

What are triglycerides: levels between 150mg/dl-500mg/dl

If you are in this category, you need to focus on your overall risk of heart disease than worry about your triglyceride levels. Yes, higher number of triglyceride has known association with increased incidence of heart disease but there is no evidence that it causes heart disease by itself.

The more important fact is: there is no evidence that taking medicine to lower your triglyceride in this category helps to reduce your risk of heart attacks.

From recent years of research, it is clear that bad cholesterol (LDL) reducing medications called statins reduce heart attacks unequivocally. If you have high risk factors for heart attack, they now recommend that you take these medications regardless of your actual cholesterol level. This recommendation applies to you too. The statin medication may not reduce your triglyceride level much but it will reduce your risk of having a heart attack.

Triglyceride level in this range does not need to be reduced with specific triglyceride lowering medication. However, it is beneficial to do other things that reduce both your heart attack risks and your triglyceride level. Unlike bad cholesterol, triglycerides respond very well to lifestyle modification.

Here are some of the proven things you can do reduce your triglyceride as well as reduce your risk of heart attack:

  1. Exercise more
  2. Avoid low fat diet
  3. Reduce intake of processed carbs
  4. Stop smoking
  5. Decrease alcohol intake
  6. Lose weigh
  7. Reduce stress

These things sound like common sense or something you would hear in a talk show, but they are certainly more beneficial than taking medication to lower triglyceride just to treat the number. If you need to take medication, take medicine that would attack the bad cholesterol, not triglyceride.

What are triglycerides: levels between 501 and 1000 mg/dl

If your triglyceride level is in this range, you are in the “grey zone.” Your triglycerides are high enough to cause a reasonable concern but not too high to unequivocally recommend starting triglyceride lowering medication right away.

The most important thing you need to do at this level is to work with your doctor to try to find out what may be causing your triglycerides to go up. You need to make sure you do not have any thyroid problems. You need to make sure you do not have undiagnosed diabetes. You need to make sure you are not taking any medication that could raise your triglyceride levels. You need to make sure you do not have any undiagnosed kidney problem.

After you do those things, you need to look at your bad cholesterol level and your overall risk for heart attack. If your bad cholesterol (LDL) is high, take statin. If you have high risks for heart attack, take statin regardless of your LDL level. The next step is to do the 7 things on the list I recommended for people with triglyceride level between 150 and 500mg/dl. After you have done all these things and your triglyceride is still high, you may need to take specific medication to lower triglycerides.

This is a decision you need to take after discussing the pros and cons with your doctor, as there are no unequivocal guidelines.

What are triglycerides: levels higher than 1000mg/dl

If your triglyceride levels are higher than 1000mg/dl, that is definitely not healthy. To give you an idea of what that is like, lets go back and redo our triglyceride level calculations. If your triglyceride level is 1000mg/dl, it means that you have about 1 whole ounce (10 times 1/10 of an ounce) of fat running in your blood. Imagine melting an ounce of butter and pouring it in a bottle containing 4/5 gallon of water. Now imagine shaking that bottle trying to dissolve it in that much water. You can imagine that your water would look milky if you were somehow able to get it dissolved.

high triglyceride milky blood

That is exactly how your blood would look if your triglyceride levels were higher than 1000mg/dl. You can look at the color of your blood in the vial when they take it and you may actually see the milky color. That level of fat in your blood is not healthy. If your triglyceride level is that high, you still need to do everything I suggested to people with triglyceride levels between 501 and 1000mg/dl. In addition to that, you may need specific medications to lower your triglyceride level.

What are triglycerides: conclusion

It took me a lot of time and dedication to put together this detailed article about triglycerides. “What are triglycerides?” is a common question I get from my patients. There are a lot of different articles about this subject on the internet but most of them only present a certain opinion or point of view. My goal was to present the whole story about what triglycerides are and what role they play in our body. If this article answered your questions, please share it with your friends and family. If you still have further question, you can ask them in the comment section. I cannot give you specific medical advice about your case but I can answer your general questions about triglycerides and cholesterol.