Short-term fish oil supplementation improved innate immunity, but increased ex vivo oxidation of LDL in man - a pilot study

Background. Fish and fish oils are rich. in the two, long. chain polyunsatu rated fatty acids (LCPUFAs) eicosapentaenoic acid (EPA, 20:5n-3) and docosa hexaenoic acid (DHA, 22:6n-3). The n-3 LCPUFAs have been reported to have b eneficial effects, on cardiovascular functions, but their role in relation to immune functions is still controversial. Aim of the study: The objective s of this study were to determine the effects of supplementation with fish oil on immune cell functions in human subjects., We have also assessed the effects on plasma lipids, antioxidant status, and susceptibility of low-den sity lipoproteins (LDL) to oxidative stress., The antioxidant status was de termined by measuring plasma vitamin C, tocopherols and carotenoids in plas ma and LDL, and superoxide dismutase (SOD) in red blood cells. Design: For 30, days, 10, volunteers ingested 25 g/d of either fish oil, providing n-3 LCPUFAs, (7.5 g),. or high-oleic sunflower oil, providing monounsaturated f atty acids mainly as oleic add (22 g). The oils, contained similar profiles , of tocopherols. At day 0 and day 30, blood samples were drawn by venipunc ture for plasma lipid and antioxidant analyses and lipoprotein isolation, a nd for isolation and functional tests of mononuclear cells and granulocytes . Fatty acid profiles of immune cells and LDL were also determined. Results . Fish oil supplementation resulted in an accumulation of n-3 LCPUFAs (EPA, DHA); in LDL and immune cells. The, phagocytic activity, a measure of immu ne cell activity, was increased in both groups. Whereas the plasma and LDL andoxidant status, do not appear to be affected by fish oil supplementation , an increased susceptibility of LDL to oxidation was observed in these hea lthy volunteers. Conclusions. The optimal amounts of n-3 fatty acids, requi red to modulate immune functions remain to be established. In addition, ade quate levels of antioxidant protection need to be provided during fish oil supplementation.