INS and metabolic syndrome: Marine-derived omega-3 polyunsaturated fatty acids (n-3 PUFAs), especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), may improve MetS components through triglyceride-lowering, anti-inflammatory, and insulin-sensitizing effects; however, randomized controlled trial (RCT) results remain inconsistent, and the influence of dose and intervention duration is unclear.