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

BACKGROUND & AIMS: 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 ß-oxidation and decreasing de novo lipogenesis. Therefore, they may play an important role in prevention and therapy of NAFLD. METHODS: 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. RESULTS: 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. CONCLUSIONS: Marine n-3 PUFAs are likely to be an important tool for NAFLD treatment, although further studies are required to confirm this.

Creatine supplementation as a possible new therapeutic approach for fatty liver disease: early findings.

Over the last few years, consistent data have demonstrated that creatine (Cr) supplementation prevents the accumulation of fat in rat liver as well as the progression of fatty liver disease in different situations. Studies have demonstrated that Cr is effective and prevents fatty liver in high-fat and choline-deficient diets and in hepatoma cells in vitro. Because Cr synthesis is responsible for a considerable consumption of hepatic methyl groups, studies have tested the idea that Cr supplementation could modulate phospholipid formation and VLDL secretion. Studies have also demonstrated Cr is able to modulate the expression of key genes related to fatty acid oxidation in hepatocyte cell culture and in rat liver. However, to date, the mechanism by which Cr exerts protective effects against fatty liver is poorly understood. Therefore, the present review aims to summarize the studies involving the therapeutic use of Cr supplementation on fatty liver disease and to explore the mechanisms involved in one-carbon and fatty acid metabolism for the preventive effects of Cr supplementation on fat liver accumulation. Although a small number of studies have been conducted to date, we consider Cr as a new and promising therapeutic strategy to control fat accumulation in the liver as well as the progression of fatty liver disease.

Fish oil decreases hepatic lipogenic genes in rats fasted and refed on a high fructose diet.

Fasting and then refeeding on a high-carbohydrate diet increases serum and hepatic triacylglycerol (TAG) concentrations compared to standard diets. Fructose is a lipogenic monosaccharide which stimulates de novo fatty acid synthesis. Omega-3 (n-3) fatty acids stimulate hepatic ß-oxidation, partitioning fatty acids away from TAG synthesis. This study investigated whether dietary n-3 fatty acids from fish oil (FO) improve the hepatic lipid metabolic response seen in rats fasted and then refed on a high-fructose diet. During the post-prandial (fed) period, rats fed a FO rich diet showed an increase in hepatic peroxisome proliferator-activated receptor α (PPAR-α) gene expression and decreased expression of carbohydrate responsive element binding protein (ChREBP), fatty acid synthase (FAS) and microsomal triglyceride transfer protein (MTTP). Feeding a FO rich diet for 7 days prior to 48 h of fasting resulted in lower hepatic TAG, lower PPAR-α expression and maintenance of hepatic n-3 fatty acid content. Refeeding on a high fructose diet promoted an increase in hepatic and serum TAG and in hepatic PPAR-α, ChREBP and MTTP expression. FO did not prevent the increase in serum and hepatic TAG after fructose refeeding, but did decrease hepatic expression of lipogenic genes and increased the n-3 fatty acid content of the liver. n-3 Fatty acids can modify some components of the hepatic lipid metabolic response to later feeding with a high fructose diet.