A triglyceride is a molecule formed by three fatty acid chains linked to a molecule of glycerol (a simple sugar alcohol compound).
Triglycerides are nature’s best way of storing energy and are the most common type of fat in the body. They’re carried in the blood as lipoprotein complexes and are the end product of digesting and breaking down fats from food. They’re digested in the gut and assembled into large lipoproteins in the intestine, from where they’re distributed to the whole body. Those remaining in the blood circulation are removed by the liver.
Once they reach their target organ, triglycerides are split by enzymes to release the three fatty acids, which are used as a source of energy or stored again as triglycerides. The visible evidence of this is fat under the skin, but some fat can also be stored in the abdomen and organs. All tissues are able to use fats for energy (including the heart muscle).
The liver makes and exports triglycerides as well.
Triglycerides and heart problems
Triglycerides are usually measured as part of a standard blood lipid profile. But what do the results mean?
So far, all we know is that triglycerides have been associated with coronary artery disease (CAD), especially in women. But there’s increasing evidence that they’re also markers of low HDL cholesterol and small, dense LDL (the “bad” kind of cholesterol).
Most people with raised triglyceride levels have other major risk factors for CAD such as obesity, diabetes and high blood pressure. This has made it difficult for researchers to determine whether triglycerides are an independent risk factor for disease, or not.
What’s more, the relationship between triglycerides and high-density lipoprotein (HDL) cholesterol is complex. Whenever triglycerides are increased, HDL decreases. So it may be that part of the problem with raised levels of triglycerides is that they come with lower levels of HDL. However, there’s evidence to suggest that raised triglycerides alone pose a risk for CAD.
Very high concentrations of triglycerides are of concern as they cause inflammation of the pancreas.
A normal triglyceride reading is less than 1.7 millimoles per litre (mmol/L).
Reviewed by Prof David Marais, FCP(SA), Head of Lipidology at Groote Schuur Hospital and the University of Cape Town. January 2018.