Triglycerides (triacylglycerols or TAG’s) are molecules made of glycerol and fatty acids. They are the major form of energy storage in animals. Saturated fatty acids have higher melting point than unsaturated fatty acids because they are more dense (they have more hydrogen and fewer double bonds). Animal fats usually contain more saturated fatty acids than do vegetable oils. Therefore the melting points of animal fats are higher than those of vegetable oils.

Triglycerides are the most common lipid in our bodies and in the foods we consume. Fatty acids are not typically found free in nature; instead they are found in triglycerides. Breaking down the name triglyceride tells a lot about its structure. “Tri” refers the three fatty acids; “glyceride” refers to the glycerol backbone that the 3 fatty acids are bonded to.

Note the three fatty acids in this model of a triglyceride as represented by the white balls. The red balls represent glycerol.

Example of an unsaturated fat triglyceride. Left part: glycerol, right part from top to bottom: palmitic acid, oleic acid, alpha-linolenic acid. Chemical formula: C55H98O6

Triglycerides perform the following functions in our bodies:

• Provide energy
• Primary form of energy storage in the body
• Insulate and protect
• Aid in the absorption and transport of fat-soluble vitamins.

The three fatty acids in a triglyceride can be the same or can each be a different fatty acid. A triglyceride containing different fatty acids is known as a mixed triglyceride. An example of a mixed triglyceride is shown in the image above.