What is "eicosanoid"

n. (context biochemistry English) Any of a family of naturally-occurring substances derived from 20-carbon polyunsaturated fatty acids; they include the prostaglandins, thromboxanes, leukotrienes and epoxyeicosatrienoic acids; they function as hormones.

In biochemistry, eicosanoids are signaling molecules made by oxidation of 20-carbon fatty acids. They exert complex control over many bodily systems; mainly in growth during and after physical activity, inflammation or immunity after the intake of toxic compounds and pathogens, and as messengers in the central nervous system. Many are classified as hormones. The networks of controls that depend upon eicosanoids are among the most complex in the human body.

Eicosanoids are derived from either omega-3 (ω-3) or omega-6 (ω-6) fatty acids. In general, the ω-6 eicosanoids are pro-inflammatory; ω-3s are much less so. The amounts and balance of these fats in a person's diet will affect the body's eicosanoid-controlled functions, with effects on cardiovascular disease, triglycerides, blood pressure, and arthritis.

There are multiple subfamilies of eicosanoids, including the prostaglandins, thromboxanes, and leukotrienes, as well as the lipoxins and eoxins, and others. For each, there are two or three separate series, derived from either an ω-3 or an ω-6 EFA. These series' different activities largely explain the health effects of ω-3 and ω-6 fats.