Abstract
1. Fish oils are rich in the long-chain n-3 polyunsaturated fatty acids (PUFAs), eicosapentaenoic (20:5n-3) and docosahexaenoic (22:6n-3) acids. Linseed oil and green plant tissues are rich in the precursor fatty acid, alpha-linolenic acid (18:3n-3). Most vegetable oils are rich in the n-6 PUFA linoleic acid (18:2n-6), the precursor of arachidonic acid (20:4n-6). 2. Arachidonic acid-derived eicosanoids such as prostaglandin E2 are pro-inflammatory and regulate the functions of cells of the immune system. Consumption of fish oils leads to replacement of arachidonic acid in cell membranes by eicosapentaenoic acid. This changes the amount and alters the balance of eicosanoids produced. 3. Consumption of fish oils diminishes lymphocyte proliferation, T-cell-mediated cytotoxicity, natural killer cell activity, macrophage-mediated cytotoxicity, monocyte and neutrophil chemotaxis, major histocompatibility class II expression and antigen presentation, production of pro-inflammatory cytokines (interleukins 1 and 6, tumour necrosis factor) and adhesion molecule expression. 4. Feeding laboratory animals fish oil reduces acute and chronic inflammatory responses, improves survival to endotoxin and in models of autoimmunity and prolongs the survival of grafted organs. 5. Feeding fish oil reduces cell-mediated immune responses. 6. Fish oil supplementation may be clinically useful in acute and chronic inflammatory conditions and following transplantation. 7. n-3 PUFAs may exert their effects by modulating signal transduction and/or gene expression within inflammatory and immune cells.
Highlights
Presented at the XII Annual Meeting of the Federação de Sociedades de Biologia Experimental, Caxambu, MG, Brasil, August 27-30, 1997
Diets containing large amounts of linseed oil decrease lymphocyte proliferation compared with saturated fatty acid- or n-6 polyunsaturated fatty acids (PUFAs)-rich diets [12,17,18]
Feeding mice diets containing 100 g/kg fish oil caused a decrease in spleen natural killer (NK) cell activity compared with feeding chow or 100 g/kg corn oil [28,29]
Summary
All mammals can synthesise fatty acids de novo from acetyl coenzyme A. The introduction of a single double bond between carbon atoms 9 and 10 is catalysed by the enzyme ∆9-desaturase, which is universally present in both plants and animals This enzyme catalyses the conversion of stearic acid to oleic acid (18:1 n9). Especially the unicellular algae in phytoplankton, carry out chain elongation and further desaturation of α-linolenic acid to yield the long-chainn-3 PUFAs eicosapentaenoic and docosahexaenoic acids. Many studies have investigated the effects of the amount and type of fat in the diet upon immune cell functions, lymphocyte proliferation in response to mitogens These studies have been reviewed several times in recent years [1,2,3,4,5,6,7,8,9]; the effects of n-3 PUFAs are the most well documented and will be summarised here
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
