Purified Eicosapentaenoic Acid Reduces Small Dense LDL, Remnant Lipoprotein Particles, and C-Reactive Protein in Metabolic Syndrome

E icosapentaenoic acid (EPA), one rep-resentative of n-3 unsaturated fattyacids (n-3 PUFAs), is clinically used for its lipid-lowering effects (1). n-3 PUFAs were shown to exert various phys-iological functions such as antiplatelet ac-t ions (by antagonizing effects of arachidonic acid) and plaque stabilization (2,3). Several epidemiological studies have explored antiatherogenic and car-dioprotective effects of n-3 PUFA that are abundantly contained in fish oil (4). Dys-lipidemia accompanying the metabolic syndrome is often associated with ele-vated levels of remnant lipoprotein parti-cles and small dense LDL (sdLDL), which are newly recognized risk factors for car-diovascular disease (CVD) (5). It was re-ported that fish oil improved lipoprotein subclass profiles in subjects with an atherogenic lipoprotein phenotype (6). Besides EPA, docosahexaenoic acid and cholesterol are present in fish oil (7), but it is not clear whether purified EPA inde-pendently affects lipoprotein subclass profiles. Therefore, we used purified EPA ethyl ester and examined effects of EPA on atherogenic sdLDL particles and remnant lipoprotein particles in the metabolic syn-drome, a precursor of CVD. Furthermore, sdLDL has been reported to synergisti-cally interact with inflammation in patho-physiologic processes leading to CVD (8). Therefore, we simultaneously measured effects of EPA on C-reactive protein (CRP), a marker of inflammation, and ex-amined how alteration of lipoprotein pro-fi le s by EPA af f ec t s sys temic inflammation.