Fish oil N-3 polyunsaturated fatty acids selectively affect plasma cytokines and decrease illness in Thai schoolchildren: a randomized, double-blind, placebo-controlled intervention trial

Objective To determine whether very long–chain n-3 polyunsaturated fatty acids (PUFAs) affect illness and selected plasma cytokines in schoolchildren.Study design Thai schoolchildren aged 9 to 12 years consumed milk containing placebo (soybean) oil (n = 86) or fish oil (n = 94) on 5 days per week for 6 months; the latter provided 200 mg eicosapentaenoic acid plus 1 g docosahexaenoic acid daily. Episodes and duration of illness were recorded, and plasma interleukin (IL)-2 receptor, IL-6, IL-10, and transforming growth factor (TGF)-beta1 concentrations and the fatty acid profile of plasma phosphatidylcholine determined.Results After intervention, very long–chain n-3 PUFAs were higher in plasma phosphatidylcholine in the fish oil group than in the placebo group (P < .001). The fish oil group showed fewer episodes (P = .014) and shorter duration (P = .024) of illness (mainly upper respiratory tract) than the placebo group. Plasma IL-2 receptor, IL-10, and IL-6 were not affected by either treatment. Plasma TGF-beta1 increased in both groups, but the increase was smaller in the fish oil group, and at the end of supplementation TGF-beta1 concentration was lower in the fish oil group (P < .001).Conclusions Very long– chain n-3 PUFAs reduce illness, mainly infections, in healthy Thai schoolchildren.Abbreviations: DHA, Docosahexaenoic acid; DPA, Docosapentaenoic acid; ELISA, Enzyme-linked immunosorbent assay; EPA, Eicosapentaenoic acid; IL, Interleukin; PC, Phosphatidylcholine; PUFA, Polyunsaturated fatty acid; sIL-2R, Soluble interleukin-2 receptor; TGF, Transforming growth factor; TNF, Tumor necrosis factor; UHT, Ultra-high temperatur