n - 3 Docosapentaenoic acid: the iceberg n - 3 fatty acid

PURPOSE OF REVIEW: Docosapentaenoic acid (DPA) is a minor omega-3 fatty acid (FA) which has been frequently overlooked in lipid research. This review examines the biochemical and physiological outcomes of human trials which have used pure preparations of DPA (n - 3 DPA) and also recent developments in specialized proresolving lipid mediators (SPMs) derived from n - 3 DPA. RECENT FINDINGS: There have been only been two human studies and eleven animal studies with pure n - 3 DPA. The doses of n - 3 DPA used in the human trials have been 1-2 g/day. n - 3 DPA abundance is increased in blood lipid fractions within 3-4 days of supplementation. n - 3 DPA has the potential for unique properties, with a greater similarity in biological functioning with docosahexaenoic acid (DHA), than eicosapentaenoic acid (EPA). Despite the typically low levels of n - 3 DPA in most tissue lipids relative to EPA and DHA, unique SPMs, such as resolvins, maresins and protectins of the n - 3 DPA type, are involved in resolution of inflammation and regulating immune function. SUMMARY: We suggest that measurement of blood levels of n - 3 DPA gives no indication of its broad biological roles, but that the true functionality of this enigmatic n - 3 polyunsaturated fatty acid (PUFA) remains obscure until more is known about the properties of the unique DPA-derived SPMs.