Fats Handbook

Naming Fatty Acids

Scientific Names

Systematic scientific names of fatty acids are derived from the name of the parent hydrocarbon with the substitution of oic for the final e. For example, octadecane is a hydrocarbon with 18 carbons in its chain; the fatty acid is called octadecanoic acid. The same fatty acid with one double bond is called octadecenoic acid; with two double bonds, octadecadienoic acid; and with three double bonds, octadecatrienoic acid.Greek prefixes (di, tri, tetra, penta, hexa, etc) are used to designate the number of carbons in the carbon skeleton and also to designate the number of double bonds. Numbers preceding the name indicate the locations of the double bonds. For example, 9, 12-octadecadienoic acid is a fatty acid with 18 carbon atoms with two double bonds located between carbons 9 and 10 and 12 and 13. By convention, the carbon on the carboxyl or acid group is carbon 1. The common name for this acid is linoleic acid.

Common Names

Common names were given fatty acids before a systematic naming system was created. Often these names were based on the source of where it was discovered. For example, lauric acid (C12:0) is a widely occurring fatty acid in Lauraceae seeds where it was discovered. Common names are still widely used in naming fatty acids. See Table at bottom of fat glossary for common names for other fatty acids.

Abbreviated Notations

Fatty acids are often abbreviated by designating the number of carbons followed by a colon and the number of double bonds. For example, oleic acid can be abbreviated C18:1 n-7. Polyunsaturated fatty acids are also given an additional notation of their omega family. The omega family is also identified using the notation n-3 or n-6. The first double bond away from the omega end of the carbon chain designates the omega family. If the first double bond is three carbons from the end of the carbon chain, the fatty acid is in the omega-3 family. Likewise, if the number of carbons to the first double bond is six, then the fatty acid is in the omega-6 family. For example, C18:3 n-3 is a fatty acid with an 18 carbon skeleton. It contains 3 double bounds and it is in the omega-3 family since there is a double bond three carbons from the end (omega). Its common name is alpha-linolenic acid.

Glossary of Chemical Terms

Alpha-linolenic acid: the short-chain (fewer than 20 carbon atoms) omega-3 essential fatty acid found in flaxseeds and some plants.

Atherosclerosis: the result of deposition of excess triglycerides and cholesterol from the bloodstream onto the walls of the arteries. This material hardens and the diameter of the blood vessels decrease causing friction and interference with rate of blood flow. The deposit that has formed may cause clots as the blood flows over its surface, and can lead to heart attack.

Cholesterol: a sterol found in animal. It occurs is all cells of the body but particularly in brain and nerve tissue. Cholesterol is synthesized in the body, primarily in the liver, but skin, intestines and other tissue can synthesize it. The other primary source of cholesterol in the body comes from animal and meat products in the diet. It is not found in plants. Cholesterol is important as a precursor of important steroids such as vitamin D, the sex hormones, and the adrenocortical hormones.

Cis-fatty acids: refers to the shape or configuration of the unsaturated fatty acid. Most naturally occurring unsaturated fatty acids have cis-configurations with their hydrogen atoms on the same side of the double bond which produces a ‘kink’ (V-shaped) in the chain. When incorporated into cell membranes, this kink doesn’t allow them to pack tightly which makes the membrane more flexible.

Eicosanoids: biologically very active compounds that contain twenty carbon atoms and are critical for body functions. They are derived from the highly unsaturated fatty acids, arachidonic acid and eicosapentaenoic acid. Eicosanoids elicited by EPA are chemically and biologically distinct from those formed from AA and activate functions in the body opposite of those activated by AA. Eicosanoids are found in tissues throughout the human body; they are formed from released membrane fatty acids which give the body the capacity to produce quick and localized action and are extremely vital in every aspect of our health. They are involved with blood clotting, inflammation and initiation of immune defense.

Eicosanoid classes: classes of potent, hormone-like compounds formed by the release of either AA (omega-6) or EPA (omega-3) from cell membranes. The three major classes are prostaglandins, leukotrienes and thromboxanes. Each class of eicosanoids can be elicited by both AA and EPA and though these n-3 eicosanoils are very similar in structure to the n-6 eicosanoids, their effects in the body are opposite. For example, the omega-3 EPA elicits prostaglandin PGI3 while the omega-6 arachidonic acid elicits prostaglandin PGI2. The omega-3 produced eicosanoids elicit anti-inflammatory responses while omega-6 eicosanoids elicit inflammatory responses. When the diet contains high concentrations of omega-6 fatty acids, cell membranes have high concentrations of omega-6, and the highly potent eicosanoids that are produced by the omega-6 precursor, arachidonic acid, are released.

Essential fatty acids (EFA): those polyunsaturated acids that the human body cannot make or be derived from other fatty acids but are required in the human diet for growth and functioning of the body. They include alpha-linolenic acid, EPA and DHA.

Fatty acids: compounds made up of carbon, hydrogen and oxygen arranged in a carbon chain skeleton with a carboxyl group (-COOH) at the alpha end (carbon number 1). Fatty acids in biological systems usually contain an even number of carbon atoms, typically between 8 and 24; the 16- and 18-carbon fatty acids are the most common. Fatty acids are the building blocks for triglycerides and important phospholipids which make up the membranes of all cells. They serve as intracellular messengers, act as hormones, and are stored as triglycerides to be used for energy. Fatty acids differ from each other by their number of carbon atoms and the number and placement of their double bonds. There are three classes of fatty acids: saturated, monounsaturated, and polyunsaturated.

Fats: mixtures of triglycerides, the storage form of fatty acids. When triglycerides contain a predominance of saturated fatty acids, they are solid and are referred to as fats.

Inflammation: the mechanism of the body’s healing system that increases circulation and immune activity at sites of injury and infection. Prostaglandins are hormone-like compounds synthesized from fatty acids by the body that control inflammation. Depending on which fatty acids predominate in the diet, the synthesis can favor either prostaglandins that are decrease inflammation or prostaglandins that increase inflammation.

Inflammatory diseases: diseases or disorders caused by persistent chronic inflammation. They are a symptom of imbalance of the hormones that control them. Arthritis, lupus, tendonitis, gingivitis, diabetes, Crohn’s diseae, psoriasis, asthma, multiple sclerosis, rheumatoid arthritis and colitis are characterized by and the imbalance of omega-6 and omega-3 fatty acid derived eicosanoids. This imbalance can result in an immune system out of control. Many of the chronic inflammatory diseases are caused by an overproduction of the leukotrienes derived from arachidonic acid.

Lipoproteins: lipids like triglycerides and cholesterol complexed with proteins to make them water soluble so that they can be transported in the bloodstream.

Lipoprotein classes: include chylomicrons, very low density lipoproteins (VLDL), low density lipoproteins referred to as ‘bad’ cholesterol (LDL), and high density lipoproteins (HDL). The concentration of cholesterol in blood plasma is primarily determined by the amount of LDL. HDL contains 50% protein and is the smallest lipoprotein. Since HDL has very little cholesterol, it may take cholesterol from cells and other lipoproteins and transport it to the liver. It is considered ‘good’ cholesterol.

Long-chain fatty acids: fatty acids having 20 or more carbons in their chains. Eicosapentanoic acid and docosahexaenoic acid are the long-chain essential fatty acids found only in marine fish.

Monounsaturated fatty acid: a fatty acid whose carbon chain contains one double bond (missing two hydrogen atoms).

Oils: mixtures of triglycerides, the storage form of fatty acids. When they contain an abundance of unsaturated fatty acids, they are liquid at room temperature and are referred to as oils.

Omega-3 fatty acid: a polyunsaturated fatty acid whose first double bond is located three carbons from the end of the carbon chain. Alpha-linoleic acid is the parent omega-3 essential fatty acid. The body can make the long-chain fatty acids EPA and DHA if enough alpha-linoleic acid is present, but with such poor efficiency that they are considered essential fatty acids.

Omega-6 fatty acid: a polyunsaturated fatty acid whose first double bond is located six carbons from the end of the carbon chain. Linoleic acid is the parent omega-6 essential fatty acid. Aracidonic acid is also considered an essential fatty acid even though it can be synthesized to some degree in the human body if sufficient linoleic acid is present.

Polyunsaturated fatty acid: a fatty acid whose carbon chain contains two or more double bonds. There are two families of polyunsaturated fatty acids, the omega-3 and the omega-6 family. Though structurally, these two families are very similar, their functions are very different. They are metabolically equivalent, but they are not interconvertible, that is, an omega-3 fatty acid cannot be converted to an omega-6 fatty acid or vise versa.

Saturated fatty acid: a fatty acid whose carbons contain all hydrogen atoms they can hold. The saturated carbon chain is straight..

Trans fatty acids: unnatural fatty acids created by a commercial hydrogenation process that adds hydrogen atoms to unsaturated oils to decrease the number of double bonds making a more pliable stable product (margarines and shortenings). The hydrogenation process stabilizes unsaturated oils against oxygenation, thus increasing their shelf life. Hydrogenation breaks the double bonds and produces fatty acids in the trans configuration that look more like a ‘straight’saturated fatty acid. When incorporated into cell membranes, the membranes are denser, causing cell functions to be altered.

Triglyceride: a compound formed from one molecule of glycerol and three fatty acids. Glycerol can combine with up to three fatty acids to form monoglycerides, diglycerides, and triglycerides. Each fatty acid attached to glycerol can contain a different chain length and degree of saturation, making one fat different from another. Triglycerides float on water and can be liquid or solid at room temperature depending on what fatty acids make up the triglycerides.

Unsaturated fatty acid: the term given for a fatty acid having one or more double bonds.

Chemical Names and Descriptions of Common Fatty Acids
Common Name Carbon Atoms Double Bonds Scientific Name Scientific Notation

Lauric acid

12 0

Dodecanoic acid

C12:0

Myristic acid

14 0

Tetradecanoic acid

C14:0

Palmitic acid

16 0

Hexadecanoic acid

C16:0

Palmitoleic acid

16 1

9-Hexadecenoic acid

C16:1n-7

Stearic acid

18 0

Octadecanoic acid

C18:0

Oleic acid

18 1

9-Octadecenoic acid

C18:1n-9

Linoleic acid

18 2

9,12-Octadecadienoic acid

C18:2n-6

Alpha-Linolenic acid

18 3

9,12,15-Octadecatrienoic acid

C18:3n-3

Arachidic acid

20 0

Eicosanoic acid

C20:0

Arachidonic acid (AA)

20 4

5,8,11,14-Eicosatetraenoic acid

C20:4n-6

EPA

20 5

5,8,11,14,17-Eicosapentaenoic acid

C20:5n-3

DHA

22 6

4,7,10,13,16,19-Docosahexanoic acid

C22:6n-3

Common fatty acids and their scientific names and notations