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.