Understanding the role of triglycerides in cardiovascular disease

The role of triglyceride in cardiovascular disease has been controversial.


Triglycerides: what are they?

Tryglicerides are the main form of fat in the body. They are the fats our bodies burn for fuel.

The lipids we get from food are converted into triglycerides in the liver from where they are released into the bloodstream to feed the body.



Taxis, bus, and trucks to deliver them

As cholesterol is carried into the bloodstream in some kind of taxi, LDH and HDL triglycerides are moved to the bloodstream by lipoproteins, another type of vehicle.

The most important transportation mode of triglyceride-rich lipoproteins are chylomicrons and by very low-density lipoprotein (VLDL) particles.

Chylomicrons may be seen as large trucks and the VLDL as taxis, since they are much smaller in size.


Dietary fats

In fact, dietary fats are digested into triglycerides in the intestine. They are incorporated into chylomicrons in the intestine and transported over to the liver.


VLDL taxi to feed the body    

The triglycerides are then carried by a VLDL taxi from the liver to the bloodstream.

They are released and go towards the cells where they are broken down by a protein or enzyme, allowing them to get inside the cells.


The carrier gets smaller as it unloads the triglycerides

The carrier reduces in size after unloading the triglycerides. It is much like, for instance, a bunch of grapes; as you remove the grapes one by one, the bunch gets smaller and smaller.

The outcome for chylomicrons and VLDL vehicles is very similar. While dumping almost all of their loads, chylomicrons remnants are created; VLDL particles are broken down into smaller size pieces known as Intermediate-Density Lipoprotein (IDL) particles.

These tiny components are used by the body for muscle energy, adipose (fat) tissue storage, and other purposes.


The well-known effects of cholesterol

Clinical focus has long been set on reducing high cholesterol levels, and particularly LDL cholesterol, to minimize the risk of cardiovascular events such as myocardial infarction or stroke.


The triglyceride controversy

Triglycerides, on the other hand, have been considered as a lesser risk factor for cardiovascular disease.

It may be noted, however, that there is now an increase of publications in the medical literature supporting the theory that high triglyceride levels, or hypertriglyceridemia, do play a causative role in the development of cardiovascular disease.


Is there a connection between triglycerides and vascular plaque build-up?

How can triglycerides lead to heart disease? Chylomicrons and VLDL are large particles that cannot penetrate the arterial wall due to their size.

However, once they are broken down into small triglyceride-rich remnants, it is easy for them to penetrate the arterial membrane.

They are then gulped down by macrophages, which are large cleaning cells. Once the macrophages are laden with lipids, they are known as foam cells because of their foamy appearance.

The macrophages become gigantic in size as they are bloated with fats, preventing them from going back into the bloodstream.

They become trapped in the arterywall where they die after dumping their lipidic content.  This mess brings on inflammation, attracting other cleaning cells. This is how plaque is formed. 


Responsible or not

Triglycerides can therefore be considered atherogenic (contributing to the formation and progression of atherosclerotic plaque), and high triglyceride levels play a causal role in coronary artery disease.


Why is it a controversial issue?

The reason behind the continued controversy in discerning a link to cardiovascular disease is that triglyceride transporter remnants contain cholesterol.

Researchers have suggested that their cholesterol content is what contributes directly to the progression of atherosclerosis, rather than the triglycerides themselves.

This is difficult to confirm.


Other possibilities or additive effect

Furthermore, we know from the bad cholesterol “taxis” (LDL) that triglycerides contribute to plaque formation also.

Like pollution caused by our cars on the roads, certain proteins that are part of the “taxis” produce inflammation as well and could be involved in plaque formation.

Researchers are currently interested in these proteins; their goal is to find a medication that could lower triglyceride levels and thus have a beneficial impact on cardiovascular health.



Effect of lowering high triglyceride levels

Lowering high triglyceride levels is still recommended since recent research findings show that triglyceride levels can predict to some extent both short- and/or long-term cardiovascular mortality.

Results from ongoing outcomes trials are expected to provide definitive evidence of the relationship between high triglyceride levels and the risk of cardiovascular disease.


How to reduce high triglyceride levels in the body

Reduction of triglycerides can be achieved by healthy lifestyle measures such as exercising regularly, maintaining a healthy diet, and limiting alcohol intake.

In certain cases, medications such as statins, fibrates, omega-3 polyunsaturated fatty acid supplements or niacin may be prescribed, if necessary.


No specific medication

There are currently no medications that specifically target the lowerihg of triglyceride levels in order to decrease the risk of cardiovascular disease, and very limited interest was shown in developing pharmaceuticals with this intent.


For the future

Hopefully, with a growing interest in understanding the impact of triglycerides levels on cardiovascular disease, the development of knowledge, awareness, and treatment options for hypertriglyceridemia will continue to progress and put an end to this controversy.