Perilla oil is derived from the seeds of Perilla frutescens and is notably rich in alpha-linolenic acid (ALA), an omega-3 polyunsaturated fatty acid. The interest in perilla oil for supporting the prostaglandin system stems from the role of ALA and its metabolites in modulating inflammation and prostaglandin synthesis. Prostaglandins are lipid compounds derived from fatty acids and have important roles in inflammation and homeostasis. Omega-3 fatty acids like ALA can be converted in the body to eicosapentaenoic acid (EPA), which competes with arachidonic acid (an omega-6 fatty acid) for the same enzymatic pathways. This competition can lead to the production of less inflammatory prostaglandins (such as PGI3 and PGE3) compared to those derived from arachidonic acid (such as PGE2).

Some animal and in vitro studies have demonstrated that perilla oil supplementation can modify the fatty acid composition of cell membranes and reduce the synthesis of pro-inflammatory prostaglandins. Human studies specifically examining perilla oil's effect on prostaglandin profiles are limited, but broader research on ALA suggests a potential for modulating inflammatory responses. Overall, while there is scientific rationale and some supporting evidence, direct clinical evidence in humans is moderate, justifying a rating of 3 out of 5 for perilla oil's use in supporting the prostaglandin system.