triglyceride

Triglyceride, also known as triacylglycerol, is a lipid formed by glycerol esterified with three fatty acids. It is the predominant storage form of fat in animals and the major lipid component of dietary fat. The fatty acids attached to the glycerol backbone vary in length and saturation, which influences the physical properties of the molecule.

In the body, triglycerides are stored in adipose tissue within lipid droplets and serve as a dense energy reserve, providing about 9 kcal per gram when mobilized. They also contribute to insulation and, in some organisms, buoyancy. Triglycerides are not major components of cell membranes.

Digestion and transport: In the small intestine, pancreatic lipase hydrolyzes dietary triglycerides to free fatty acids and monoacylglycerol, which are absorbed by enterocytes and re-esterified into triglycerides. These are packaged into chylomicrons and released into the lymphatic system and bloodstream. In circulation, lipoprotein lipase hydrolyzes triglycerides in chylomicrons and VLDL to free fatty acids for tissue uptake; glycerol released during lipolysis is transported to the liver.

Regulation and health: Hormone-sensitive lipase mediates triglyceride breakdown in adipose tissue during fasting or energy demand. Persistently elevated fasting triglycerides (hypertriglyceridemia) are associated with cardiovascular risk and pancreatitis; levels are influenced by genetics, obesity, insulin resistance, diet, alcohol, and certain medications.

Dietary sources: Triglycerides are the main form of fats in foods, including animal fats, dairy products, and vegetable oils. They are digested and absorbed as part of lipid metabolism and are the primary form in which fats are stored in the body.