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 polyunsaturated fatty acids (LCPUFAs) eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3). The n-3 LCPUFAs have been reported to have beneficial effects on cardiovascular functions, but their role in relation to immune functions is still controversial.


OBJECTIVE
The objectives 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-density lipoproteins (LDL) to oxidative stress. The antioxidant status was determined by measuring plasma vitamin C, tocopherols and carotenoids in plasma and LDL, and superoxide dismutase (SOD) in red blood cells.


METHODS
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 fatty acids mainly as oleic acid (22 g). The oils contained similar profiles of tocopherols. At day 0 and day 30, blood samples were drawn by venipuncture for plasma lipid and antioxidant analyses and lipoprotein isolation, and for isolation and functional tests of mononuclear cells and granulocytes. Fatty acid profiles of im mune 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 immune cell activity, was increased in both groups. Whereas the plasma and LDL antioxidant status do not appear to be affected by fish oil supplementation, an increased susceptibility of LDL to oxidation was observed in these healthy volunteers.


CONCLUSIONS
The optimal amounts of n-3 fatty acids required to modulate immune functions remain to be established. In addition, adequate levels of antioxidant protection need to be provided during fish oil supplementation.
Turini
M E
ME
Nestec Ltd., Nestlé Research Center, Department of Nutrition, Lausanne, Switzerland. marco.turini@rdls.nestle.com
Crozier
G L
GL
Donnet-Hughes
A
A
Richelle
M A
MA
D000975:Antioxidants / Q000032:analysis; D019587:Dietary Supplements; D005231:Fatty Acids, Unsaturated; D005395:Fish Oils / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D007111:Immunity, Cellular / Q000187:drug effects*; D007962:Leukocytes / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D008077:Lipoproteins, LDL / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010587:Phagocytosis; D010865:Pilot Projects; D016897:Respiratory Burst
D000975:Antioxidants; D005231:Fatty Acids, Unsaturated; D005395:Fish Oils; D008077:Lipoproteins, LDL