A large group of highly bioactive hormone-like substances that can be produced in every cell from either omega-3 fatty acids or omega-6 fatty acids depending on the environment outside the cell. Eicosanoids include prostaglandins, leukotrienes, and thromboxanes that are involved in blood clotting, inflammation, and constriction of blood vessels. Eicosanoids derived from omega-6 fatty acids are pro-inflammatory, pro-blood clotting, and constrict blood vessels in opposition to those derived from the omega-3 fatty acids which do the opposite in order to keep a balance in the body.