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)-β1 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-β1 increased in both groups, but the increase was smaller in the fish oil group, and at the end of supplementation TGF-β1 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 temperature