Eicosapentaenoic acid is a nutrient whose name is commonly shortened to the acronym EPA. It is a fatty acid that is necessary for good health. Supplementation by EPA can have many beneficial effects on humans who are deficient in it. Oily fish is a major source of EPA in the diet, and the body can also make EPA from other fatty acids in foods.
Dietary fats are divided into two groups, including omega-3 and omega-6. Eicosapentaenoic acid falls into the omega-3 category. EPA from fish is usually found along with another omega-3 fatty acid called docosahexaenoic acid (DHA). The reason some fatty acids are called omega-3 is that the molecule has its first double chemical bond at the third carbon atom from one end. The omega-6 variety has its first double bond at the sixth carbon atom from one end.
The only foods high in eicosapentaenoic acid are oily fish, such as salmon and mackerel. An alternative to eating oily fish is to take fish oil supplements that contain EPA. Another omega-3 fatty acid, called alpha-linoleic acid (ALA), can be converted into EPA in the body if necessary to boost nutrient levels. ALA is found in flaxseed, walnut, and canola oils.
EPA is used as a structural material in cells. It is also a raw material for chemical cell signals called eicosanoids, which are part of the immune system. EPA also regulates the expression of some genes involved in both the immune system response and in fatty acid metabolism.
Omega-3 fatty acids as a group have many effects on human development and on health. They are necessary for children's brains to grow and for eye development. Diets low in EPA in the Western world may therefore have implications for health.
EPA and DHA appear to be beneficial in lowering blood pressure and improving existing heart disease. Fish oil can also help ease the symptoms of arthritis and ease the pain of menstruation. Eicosapentaenoic acid itself may help reduce the severity of depression.
According to the Linus Pauling Institute in the United States, eicosapentaenoic acid supplements are generally safe for adults to take. High doses may cause nausea and diarrhea. Oily fish may contain low levels of mercury, so pregnant women should limit their intake to their doctor's recommendations. EPA fish oil supplement manufacturers generally test for mercury, so fish oil is usually safe.