Non-alcoholic fatty liver disease and its treatment with n-3 polyunsaturated fatty acids

Non-alcoholic fatty liver disease (NAFLD) is a common liver disease in Western countries. Metabolic disorders which are increasing in prevalence, such as dyslipidaemias, obesity and type 2 diabetes, are closely related to NAFLD. Insulin resistance is a prominent risk factor for NAFLD. Marine omega-3 (n-3) polyunsaturated fatty acids (PUFAs) are able to decrease plasma triacylglycerol and diets rich in marine n-3 PUFAs are associated with a lower cardiovascular risk. Furthermore, marine n-3 PUFAs are precursors of pro-resolving and anti-inflammatory mediators. They can modulate lipid metabolism by enhancing fatty acid β-oxidation and decreasing de novo lipogenesis. Therefore, they may play an important role in prevention and therapy of NAFLD.

This review aims to gather the currently information about marine n-3 PUFAs as a therapeutic approach in NAFLD. Actions of marine n-3 PUFAs on hepatic fat metabolism are reported, as well as studies addressing the effects of marine n-3 PUFAs in human subjects with NAFLD.

A total seventeen published human studies investigating the effects of n-3 PUFAs on markers of NAFLD were found and twelve of these reported a decrease in liver fat and/or other markers of NAFLD after supplementation with n-3 PUFAs. The failure of n-3 PUFAs to decrease markers of NAFLD in five studies may be due to short duration, poor compliance, patient specific factors and the sensitivity of the methods used.

Marine n-3 PUFAs are likely to be an important tool for NAFLD treatment, although further studies are required to confirm this.