“Omega-3s play important roles in the body as components of the phospholipids that form the structures of cell membranes [5]. DHA, in particular, is especially high in the retina, brain, and sperm [3,5,6]. In addition to their structural role in cell membranes, omega-3s (along with omega-6s) provide energy for the body and are used to form eicosanoids. Eicosanoids are signaling molecules that have similar chemical structures to the fatty acids from which they are derived; they have wide-ranging functions in the body’s cardiovascular, pulmonary, immune, and endocrine systems [1,2].

The eicosanoids made from omega-6s are generally more potent mediators of inflammation, vasoconstriction, and platelet aggregation than those made from omega-3s, although there are some exceptions [3,7]. Because both classes of fatty acids compete for the same desaturation enzymes, ALA is a competitive inhibitor of linoleic acid metabolism and vice versa [8]. Similarly, EPA and DHA can compete with arachidonic acid for the synthesis of eicosanoids. Thus, higher concentrations of EPA and DHA than arachidonic acid tip the eicosanoid balance toward less inflammatory activity [9].”

https://ods.od.nih.gov/factsheets/Omega3FattyAcids-HealthProfessional/