n-3 PUFA and lipotoxicity

Excess lipid accumulation in nonadipose tissues may occur in the setting of high levels of plasma free fatty acids or triglycerides (TGs) in a process called "lipotoxicity". Evidence from human studies and animal models suggests that lipid accumulation in the heart, skeletal muscle, pancreas, and liver play an important role in the pathogenesis of heart failure, obesity, metabolic syndrome, and type 2 diabetes mellitus (T2DM). During the past few years, several studies have shown that n-3 polyunsaturated fatty acids (PUFA) have potentially cardioprotective effects, especially in high-risk patients with dyslipidemia, and might therefore be expected to be of benefit in T2DM. Moreover, new information has demonstrated the beneficial effects of consuming n-3 PUFA in preventing the complications of lipotoxicity. n-3 PUFA dietary intake thus had positive effects on fatty liver in patients with non-alcoholic fatty liver disease (NAFLD), with an improvement in liver echotexture and a significant regression of hepatic brightness, associated with improved liver hemodynamics. The n-3 PUFA also had beneficial effects on ectopic fat accumulation inside the heart, with stabilization of cardiac myocytes and antiarrhythmic effects. On the other hand, recent data from animal models suggest that oral dosing of eicosapentaenoic acid (EPA) could contribute to protect against P-cell lipotoxicity. This review discusses the latest hypotheses regarding lipotoxicity, concentrating on the impact of the n-3 PUFA that contribute to ectopic lipid storage, affecting organ function. Further human studies are needed to test the evidence and elucidate the mechanisms involved in this process. (C) 2009 Elsevier B.V. All rights reserved.