What Is The Difference Between A Fatty Acid And A Triglyceride?

There are many differences between a triglyceride and a fatty acid. However, it may be more informative to focus on the similarities. Both are commonly referred to as fat, but "triglyceride" is the scientific term for fat. The fatty acids in triglycerides determine the type of fat.

Fatty Acids

Fatty acids are made up of carbon chains that also contain hydrogen and oxygen. They are categorized by chain length, as in short-, medium- or long-chain fatty acids. The number of double bonds will also determine the type of fatty acid. For instance, saturated, monounsaturated and polyunsaturated describe fatty acids that contain none, one and more than one double bond, respectively. Fatty acids can be part of other compounds in the body but are also the major parts of triglycerides.

Triglycerides

Triglycerides, also known as triacylglycerols, are made up of three fatty acids connected together. Your body continually makes triglycerides from fatty acids and vice versa. Fats and oils, which are simply liquid fats, are 95 percent triglycerides. These triglycerides are usually a mixture of many different fatty acids. Whether a fat is considered mostly saturated, monounsaturated or polyunsaturated will be determined by the major fatty acids in the triglycerides. For instance, olive oil is considered a monounsaturated fat because it contains a lot of oleic acid, a monounsaturated fatty acid. Fats are always a mixture of fatty acids, and approximately one-quarter of the other fatty acids in olive oil are saturated or polyunsaturated. Seven fatty acids occur commonly in your body and the food you eat. Of these seven, two are considered "essential," meaning your body cannot make them and therefore you must obtain them from your diet.

Triglycerides and Fatty Acids in Food

Because saturated fatty acids have no double bonds, the chains are straight, pack together tightly and are solid at room temperature. The double bonds in polyunsaturated fatty acids causes kinks in the chain and therefore cannot pack together tightly. This results in oils that are liquid at room temperature. The oil may even stay liquid in the fridge if it has a lot of polyunsaturated fatty acids with many double bonds. Cold-water fish tend to have an abundance of long kinked polyunsaturated fatty acids that have four or five double bonds, so their bodies don't solidify in the freezing Arctic waters.

Food labels quantify the fatty acids in a food item, but these are actually in the form of triglycerides. "Free fatty acids" refer to fatty acids that are not in triglyceride form. Free fatty acids tend to taste "off" and only occur in very small amounts in foods.

Triglycerides and Fatty Acids in the Body

In the body, triglycerides are an important energy source and are stored for later use in fat tissue, muscle tissue, liver and mammary glands. Triglycerides and free fatty acids are transported around your body in the bloodstream. Lab tests will show whether your levels are in the normal range. Elevated levels of either of these compounds in your blood may put you at increased risk for heart disease.