Fats - Triglycerides

The most common dietary fats are triglycerides. They comprise approximately 95 percent of all ingested fats. A triglyceride is composed of a glycerol molecule with three fat molecules. These fat molecules are called fatty acids.

A fatty acid molecule is composed of a long chain of carbon molecules with an acid group on one end (see The body handles dietary triglycerides by breaking the bond between the glycerol and the fatty add. This breaking of the chemical bond is achieved by emulsifying the triglyceride with bile so that enzymes (lipases) can add water to the glycerol molecule. When this happens, the fatty acid is liberated from the glycerol molecule. This process happens during digestion.

Initially the triglyceride is converted into a diglyceride, then a monoglyceride. The body can absorb free fatty acids, glycerol, and monoglycerides much easier than the bulkier tri- and diglycerides. Once digested, the free fatty acids and monoglycerides are absorbed into the body and transported by special protein-wrapped molecules known as lipoproteins.

The major categories of lipoproteins are very low-density lipoprotein (VLDL), low-density lipoprotein (LDL), and high-density lipoprotein (HDL). VLDL and LDL are responsible for transporting fats (primarily triglycerides and cholesterol) from the liver to body cells, and HDL is responsible for returning fats to the liver; therefore, elevations of either LDL or VLDL are associated with an increased risk for developing atherosclerosis, the primary cause of a heart attack or stroke. In contrast, elevations of HDL are associated with a low risk of heart attacks. 

Last Update: September 06, 2003