What are Triglycerides?

Triglycerides are the most common type of fat digested in the body and can be either consumed in the diet or produced in the body. They normally circulate in the bloodstream to supply energy to cells and are stored in body fat as an emergency store of energy.

If there are excessive levels of triglycerides in the body, the level of triglycerides circulating in the bloodstream and stored in body fat elevates and obesity becomes more common. This is also known as hypertriglyceridemia and is linked to an increased risk of other health conditions such as cardiovascular disease      

Chemical Composition

A triglyceride is formed when the three hydroxyl (OH-) groups of a single glycerol molecule react with the carboxyl group (COOH-) of three fatty acids by forming ester bonds.

The three fatty acids included in the structure of the triglyceride may or may not be the same in different triglycerides, such that there are many possible variations. The length of the fatty acid chains occurring in triglycerides can vary but are most commonly 16, 18 and 20 carbons.

Chemical Metabolism

Triglycerides can be broken down through a reaction involving the pancreatic lipase enzyme that is responsible for hydrolyzing the ester bonds and allowing the fatty acids to be released from the glycerol molecule.

Triglycerides must be broken down in order to provide the body with energy, as the duodenum cannot absorb lipids in the triglyceride form.

Role in the Body and Disease

Triglycerides are utilized in the body by offering a source of energy to cells that require it. They are a normal component of the blood and are naturally stored in fat deposits. However, when present in excess triglycerides can cause problems in the body and lead to serious diseases.

High levels of triglycerides are associated with a group of disorders collectively known as metabolic syndrome, which increases the risk of an individual being affected by diabetes, stroke or cardiovascular disease.

Normal Physiological Levels

The body needs some triglycerides to be present in the bloodstream as they are utilized as an energy source. Blood tests are usually used to determine the level of triglycerides in the body and several tests may be required to confirm accurate results.

Triglycerides are measured in mmol/L and are classified as follows:

Normal: less than 1.7 mmol/L
Borderline high: 1.7 – 2 mmol/L
High: 2 – 6 mmol/L
Very high: more than 6 mmol/L

The blood sample used in the test should be taken after fasting for 12 hours, to lessen the impact of recent consumption of food on triglyceride levels in the blood.

Causes of High Triglycerides

The most common cause of high triglycerides is habitual overeating. Some other circumstances may also contribute to increased triglyceride levels, however, including alcohol consumption, uncontrolled diabetes, hormone abnormalities, medication use, kidney disease, liver disease and some genetic disorders.

References

• http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Triglycerides?open
• http://www.nlm.nih.gov/medlineplus/ency/article/003493.htm
• http://www.mayoclinic.org/diseases-conditions/high-blood-cholesterol/in-depth/triglycerides/art-20048186

Further Reading

• All Triglyceride Content
• Triglycerides – What do they do?
• Triglycerides and Disease

Written by

Yolanda Smith

Yolanda graduated with a Bachelor of Pharmacy at the University of South Australia and has experience working in both Australia and Italy. She is passionate about how medicine, diet and lifestyle affect our health and enjoys helping people understand this. In her spare time she loves to explore the world and learn about new cultures and languages.