Background: Evidence of predictive power of various fatty acids on the risk of metabolic syndrome was scanty. We evaluated the role of various fatty acids, including saturated fat, monounsaturated fat, transfat, n-6 fatty acid , eicosapentaenoic acid EPA and docosahexaenoic acid DHA, for the risk of the metabolic syndrome in Taiwan. Results: A nested case- control study based on 1000 cases of metabolic syndrome and 1: 1 matched control subjects. For saturated fat, monounsaturated fat and transfat, the higher the concentration the higher the risk for metabolic syndrome: participants in the highest quintile had a 2.22-fold 95% confidence interval [CI], 1.66 to 2.97 higher risk of metabolic syndrome. In addition , the participants in higher EPA quintiles were less likely to have the risk of metabolic syndrome adjusted risk, 0.46 [0.34 to 0.61] for the fifth quintile. Participants in the highest risk group low EPA and high transfat had a 2.36-fold higher risk of metabolic syndrome 95% CI, 1.38 to 4.03, compared with those in the lowest risk group high EPA and low transfat. For prediction power, the area under ROC curves increased from 0 .926 in the baseline model to 0.928 after adding fatty acids. The net reclassification improvement for metabolic syndrome risk was substantial for saturated fat 2.1%, P = 0.05. Conclusions: Plasma fatty acid components improved the prediction of the metabolic syndrome risk in Taiwan. ; 流行病學與預防醫學研究所 ; 公共衛生學院 ; 期刊論文