Omega-3 fatty acid

Omega-3 fatty acids are a family of polyunsaturated fatty acids which have in common a carbon-carbon double bond in the ω-3 position. (See Nomenclature for terms and discussion of ω (omega) nomenclature.)

Important omega-3 fatty acids in nutrition are: α-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). For a more complete list see List of omega-3 fatty acids. The human body cannot synthesize omega-3 fatty acids de novo, but can synthesize all the other necessary omega-3 fatty acids from the simpler omega-3 fatty acid α-linolenic acid. Therefore, α-linolenic acid is an essential nutrient which must be obtained from food, and the other omega-3 fatty acids which can be either synthesized from it within the body or obtained from food are sometimes also referred to as essential nutrients.