Role of Omega-3 Polyunsaturated Fatty Acids in Human Health: Chemistry, Mechanisms, and Clinical Evidence

Omega-3 polyunsaturated fatty acids (PUFAs) are a structurally distinct class of lipids characterized by a cis double bond at the third carbon from the methyl (ω) terminus. Major nutritionally relevant forms include α-linolenic acid (ALA), eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), and docosahexaenoic acid (DHA). This review synthesizes recent advances in the chemistry, metabolism, and clinical significance of omega-3 PUFAs. Emphasis is placed on their structural features, susceptibility to oxidation, conversion into specialised pro-resolving mediators, and incorporation into biological membranes. These chemical properties are linked to their mechanistic roles in cardiovascular, metabolic, neurological, inflammatory, and developmental health. Emerging aspects such as sustainable omega-3 sources, bioavailability, and the omega-3 index as a biomarker are also discussed. Current clinical evidence highlights that omega-3 PUFAs exert their effects through membrane modulation, receptor signalling, and lipid-mediator pathways. Future research should integrate lipidomics and personalised nutrition approaches to optimise therapeutic applications. Keywords: Omega-3 fatty acids; EPA; DHA; PUFA; lipid metabolism; clinical health