Omega-3 fatty acid

An omega-3 fatty acid is a polyunsaturated fatty acid whose first double bond lies three carbon atoms from the methyl end of its chain. This structural family includes essential dietary fats and longer-chain molecules used in cell membranes and signaling.

Fatty acid: A molecule with a hydrocarbon chain and a carboxyl group, used in energy storage and biological membranes. Omega-3s are classified by the structure of their fatty-acid chains.
Fatty acid metabolism: The biochemical processes that synthesize, break down, and transform fatty acids. It includes the pathways that process dietary omega-3 molecules.
Essential fatty acid: A fatty acid that an organism must obtain from its diet because it cannot synthesize enough of it. Alpha-linolenic acid is an essential omega-3 in human nutrition.
Cell membrane: A selectively permeable boundary made mainly of lipids and proteins that encloses a cell. DHA and other fatty acids contribute to the composition and properties of membranes.
Omega-6 fatty acid: A polyunsaturated fatty acid whose first double bond lies six carbon atoms from the methyl end. Omega-6s share the polyunsaturated structure but have a different double-bond position.
Polyunsaturated fat: A fat whose fatty-acid chains contain two or more carbon–carbon double bonds. Omega-3s are polyunsaturated, with multiple double bonds in each chain.
Fatty acid elongation: The enzymatic addition of two-carbon units to a fatty-acid chain. Elongation helps convert alpha-linolenic acid into longer-chain omega-3s.
Fish oil: Oil extracted from fish tissues, commonly containing EPA and DHA. It is a widely used dietary source of long-chain omega-3 fatty acids.
Inflammation: A protective biological response to harmful stimuli, involving immune cells and signaling molecules. Omega-3-derived lipids can influence inflammatory signaling and its resolution.
Saturated fat: A fat whose fatty-acid chains contain no carbon–carbon double bonds. Its chains lack the double bonds that define omega-3 fatty acids.

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