Polyunsaturated fatty acids and inflammation
Institute of Human Nutrition, School of Medicine, University of Southampton, Bassett Crescent East, Southampton SO16 7PX, U.K.
Key words: arachidonic acid, cytokine, eicosanoid, fish oil, inflammation, polyunsaturated fatty acid.
Abbreviations used: COX, cyclo-oxygenase; DHA, docosahexaenoic acid; EPA, eicosapentaenoic acid; HETE, hydroxyeicosatetraenoic acid; ICAM-1, intercellular cell-adhesion molecule 1; IL, interleukin; LOX, lipoxygenase; LT, leukotriene; NF-kB, nuclear factor kB; PG, prostaglandin; PUFA, polyunsaturated fatty acid; TNF, tumour necrosis factor; TX, thromboxane; VCAM-1, vascular cell adhesion molecule 1.
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The n–6 polyunsaturated fatty acid, arachidonic acid, is a precursor of prostaglandins, leukotrienes and related compounds that have important roles as mediators and regulators of inflammation. Consuming increased amounts of long chain n–3 polyunsaturated fatty acids (found in oily fish and fish oils) results in a partial replacement of the arachidonic acid in cell membranes by eicosapentaenoic and docosahexaenoic acids. This leads to decreased production of arachidonic acid-derived mediators. This alone is a potentially beneficial anti-inflammatory effect of n–3 fatty acids. However, n–3 fatty acids have a number of other effects that might occur downstream of altered eicosanoid production or are independent of this. For example, they result in suppressed production of pro-inflammatory cytokines and can modulate adhesion molecule expression. These effects occur at the level of altered gene expression.
Source: Biochem. Soc. Trans.. (2005) 33, (423–427)