Long-chain polyunsaturated fatty acids

Abstract

Long-chain polyunsaturated fatty acids (LCPUFAs) are derived from essential fatty acids (EFAs). EFAs cannot be made by the body and are essential nutrients. Hence they have to be obtained exogenously, as they are needed for cell membrane structure and as precursors of various eicosanoids1. It should be understood here that in the literature the terms EFAs, PUFAs (polyunsaturated fatty acids) and LCPUFAs are used sometimes interchangeably though they denote different types of fatty acids. For instance, linoleic acid (LA, 18:2 ω-6) and α-linolenic acid (ALA, 18:3 ω-3) are EFAs, whereas γ-linolenic acid (GLA, 18:3 ω-6), dihomo-GLA (DGLA, 20:3 ω-6), arachidonic acid (AA, 20:4 ω-6), eicosapentaenoic acid (EPA, 20:5 ω-3), docosapentaenoic acid (DPA, 22:5 ω-3), and docosahexaenoic acid (DHA, 22:6 ω-3) are PUFAs and are non-essential fatty acids. AA, EPA, DPA, and DHA are also called as LCPUFAs. Many times, more for the sake of convenience, LA, GLA, DGLA, AA, ALA, EPA, DPA, and DHA are collectively called as EFAs or PUFAs, though in strict sense this is not correct. Here the word LCPUFAs refers to AA, EPA, DPA, and DHA; the word EFAs stands for LA and ALA whereas PUFAs is used to denote GLA, DGLA, AA, EPA, DPA, and DHA. It should also be understood that EFAs are also PUFAs (since they contain 2 or more double bonds) but all PUFAs are not EFAs (reviewed in 1).