Professor of Nutritional Immunology University of Southampton Southampton, United Kingdom
Abstract: The marine-derived omega-3 (n-3) fatty acids EPA and DHA possess a range of anti-inflammatory actions. Increasing the content of EPA and DHA in the membranes of cells involved in inflammation has effects on the physical nature of the membranes and on the formation of signalling platforms called lipid rafts. EPA and DHA interfere with arachidonic acid metabolism which yields prostaglandins and leukotrienes involved in inflammation. In turn, EPA gives rise to weak (i.e. less inflammatory) analogues and both EPA and DHA are substrates for the synthesis of specialised pro-resolving mediators. EPA and DHA result in altered patterns of gene expression and of protein production. The net result is decreased production of inflammatory cytokines, chemokines, adhesion molecules, proteases and enzymes. The anti-inflammatory and inflammation-resolving effects of EPA and DHA are relevant to both prevention and treatment of human diseases that have an inflammatory component. Plant-derived n-3 fatty acids (alpha-linolenic acid (ALA) and stearidonic acid (SDA)) also give rise to lipid mediators that might affect inflammation, although these are less well studied than the mediators formed from arachidonic acid, EPA and DHA. ALA and SDA are also precursors for EPA biosynthesis and may act to decrease inflammation through this route. This may account for anti-inflammatory effects reported in human trials using very high intakes of ALA. A recent in vitro study comparing ALA, SDA, EPA and DHA showed only limited effects of ALA and SDA on inflammatory responses of endothelial cells, with EPA and to a greater extent DHA having significant anti-inflammatory actions.
