Reactome: A Curated Pathway Database

alpha-linolenic (omega3) and linoleic (omega6) acid metabolism (R-HSA-2046104)

Species Homo sapiens


There are two major classes of polyunsaturated fatty acids (PUFAs): the omega-3 (n-3) and the omega-6 (n-6) fatty acids, where the number corresponds to the position of the first double bond proximate to the methyl end of the fatty acid. Omega-3 and omega-6 fatty acids are considered essential fatty acids. Humans cannot synthesize them, instead they are supplied through diet. Linoleic acid (LA, 18:2(n-6)), a major component of omega-6 fatty acids and alpha-linolenic acid (ALA, 18:2(n-3)) a major component of omega-3 fatty acids are the two main dietary essential fatty acids (EFAs) in humans. ALA and LA obtained from diet are converted in the body into their longer chain and more unsaturated omega-3 and omega-6 products by a series of desaturation and elongation steps. Metabolism of ALA and LA to their corresponding products is mediated via common enzyme systems. In humans ALA is finally converted to docosahexaenoic acid (DHA, C22:6(n-3)), and LA is converted to docosapentaenoic acid (DPA, C22:5(n-6)). The intermediary omega-3 and omega-6 series fatty acids play a significant role in health and disease by generating potent modulatory molecules for inflammatory responses, including eicosanoids (prostaglandins, and leukotrienes), and cytokines (interleukins) and affecting the gene expression of various bioactive molecules (Kapoor & Huang 2006, Sprecher 2002, Burdge 2006).

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Literature References
pubMedId Title Journal Year
10903473 Metabolism of highly unsaturated n-3 and n-6 fatty acids Biochim Biophys Acta 2000
12324224 The roles of anabolic and catabolic reactions in the synthesis and recycling of polyunsaturated fatty acids Prostaglandins Leukot Essent Fatty Acids 2002