In neutrophils, 5 hydroxyeicosanoid dehydrogenase (5-HEDH) activity is localised in the microsomal fraction and requires NADP+ as a cofactor to oxidise 7-hydroxy docosahexaenoic acid (7-HDHA) to 7-oxo-docosahexaenoic acid (7-oxo-DHA) (Patel et al. 2009, Cipollina et al. 2014). Although 5-HEDH activity has been evaluated in a wide range of intact cells and in crude microsome preparations, it has not yet been purified and its structure and gene remain unknown. Dietary EPA supplementation significantly increases the formation of 7-oxo-DHA that transduces anti inflammatory actions rather than suppressing production of pro inflammatory AA metabolites (Cipollina et al. 2014).