Omega-6 (n-6) and omega-3 (n-3) polyunsaturated fatty acids (PUFA) are precursors
of potent lipid mediators, termed eicosanoids, which play an important role in the
regulation of inflammation. Eicosanoids derived from n-6 PUFAs (e.g., arachidonic
acid) have proinflammatory and immunoactive functions, whereas eicosanoids derived
from n-3 PUFAs [e.g., eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)]
have anti-inflammatory properties, traditionally attributed to their ability to inhibit
the formation of n-6 PUFA-derived eicosanoids. While the typical Western diet has
a much greater ratio of n-6 PUFAs compared with n-3 PUFAs, research has shown that
by increasing the ratio of n-3 to n-6 fatty acids in the diet, and consequently favoring
the production of EPA in the body, or by increasing the dietary intake of EPA and
DHA through consumption of fatty fish or fish-oil supplements, reductions may be achieved
in the incidence of many chronic diseases that involve inflammatory processes; most
notably, these include cardiovascular diseases, inflammatory bowel disease (IBD),
cancer, and rheumatoid arthritis, but psychiatric and neurodegenerative illnesses
are other examples.