Triglyceride
A triglyceride is a lipid made from glycerol and three fatty acids, serving as a major storage form of fat and metabolic energy.
What a triglyceride is
A triglyceride, also called a triacylglycerol, is a lipid built from one glycerol backbone and three fatty acid chains. The fatty acids are attached through ester bonds. This structure makes triglycerides hydrophobic, energy-rich, and well suited for storage in fat droplets and dietary oils.
Glycerol plus fatty acids
Glycerol has three attachment points, and each can be linked to a fatty acid. The three fatty acids in one triglyceride can be identical, but they often differ in chain length or degree of saturation. Those differences influence melting point, texture, digestion, and metabolic handling.
Energy storage
Triglycerides store more energy per gram than carbohydrates because their fatty acid chains are highly reduced and contain little water. Animals store them in adipose tissue, plants store them in seeds and oils, and many microorganisms use related lipid droplets as energy reserves.
Digestion and absorption
Dietary triglycerides are too large and hydrophobic to move freely through watery digestive fluids. Bile helps emulsify fat, and enzymes such as pancreatic lipase break triglycerides into fatty acids and monoacylglycerols. Intestinal cells then reassemble many of those pieces into triglycerides for transport.
Lipoprotein transport
Because triglycerides do not dissolve well in blood, the body packages them into lipoprotein particles. Chylomicrons carry triglycerides from the intestine after a meal, while very-low-density lipoproteins help move triglycerides made by the liver. Enzymes at tissues can release fatty acids for storage or use.
Storage and mobilization
In adipose cells, triglycerides can be stored in lipid droplets. When energy is needed, hormone-sensitive pathways stimulate lipases that break stored triglycerides into fatty acids and glycerol. Fatty acids can then travel to tissues and be oxidized for ATP production.
Clinical context
Blood triglyceride levels are often measured alongside cholesterol and lipoproteins because they reflect part of lipid transport and metabolic health. High levels can be influenced by diet, genetics, insulin resistance, alcohol use, medications, and other conditions. Interpretation depends on the broader clinical picture.
Why it matters
Triglycerides are the chemistry of stored energy made visible. They connect food, adipose tissue, liver metabolism, blood lipoproteins, and cell fuel use. Understanding them helps explain why fats and oils are energy dense, how bodies move lipid through blood, and how storage can become a metabolic signal.