ARI, acute respiratory infection; CI, confidence interval; DHA, docosahexaenoic acid; EPA, eicosapentaenoic acid; LCPUFA, long-chain polyunsaturated fatty acid; LRTI, lower respiratory tract infection; PUFA, polyunsaturated fatty acid; RCT, randomized controlled trial; RR, relative risk; TGF, transforming growth factor; URTI, upper respiratory tract infection.