The Significance of the Mediterranean Diet in the Management of Non-Alcoholic Fatty Liver Disease: A Systematic Review

Abstract

Non-alcoholic fatty liver disease (NAFLD) is the accumulation of intrahepatic fat occurring in the absence of alcohol abuse. The fatty changes in the liver are often the beginning of sequelae of complications, potentially causing steatohepatitis, liver cirrhosis, and hepatocellular carcinoma. The Mediterranean diet is not only a way of eating but is considered a lifestyle and primarily consists of a plant-based diet, with olive oil as the primary lipid. In this study, we reviewed the effectiveness of the Mediterranean diet on NAFLD and its efficacy in disease management. This systematic review follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocol (PRISMA-P) 2009 guidelines. The PubMed database was used to gather articles, using the following terms individually and in combination, "Mediterranean diet," "non-alcoholic fatty liver disease," "insulin resistance," "metabolic syndrome," "omega-3-fatty acids." A quality appraisal was completed to include 14 articles in this systematic review. The studies discuss the correlation between the Mediterranean diet and its role in preventing and treating NAFLD. Olive oil is the major monounsaturated fatty acid, whereas nuts, seeds, and fish consist largely of polyunsaturated fatty acids, both of which are essential components of the Mediterranean diet. The plant-based diet, having sufficient amounts of vegetables, legumes, and fruits, provides its anti-oxidant and anti-inflammatory effects, playing a fundamental role in preventing oxidative stress damage. Olive oil polyphenols increase apoptosis and cell cycle arrest. They also decrease proliferation and angiogenesis, all of which prevent neoplasia. Adapting the Mediterranean lifestyle has shown promising effects in NAFLD, reducing overall mortality and morbidity.

Crosstalk between dietary patterns, obesity and nonalcoholic fatty liver disease

“…This diet is known as a high-fat diet, with a fat intake of up to 45% of total daily calories[ 35 ]. The basic source of dietary fat in this diet is olive oil[ 33 , 36 ], where oleic acid, a monounsaturated fatty acid (MUFA), is a major component[ 37 ]. The MD is also characterized by high amounts of PUFAs.…”

“…It has been proven that MUFA may prevent the development of NAFLD by improving blood lipid concentrations, lowering body fat contents and decreasing postprandial adiponectin expression[ 50 ]. MUFAs (oleic acid) from olive oil have numerous beneficial effects on NAFLD, including decreased oxidized low-density lipoprotein, low-density lipoprotein cholesterol (LDL-C) and TG concentration, without the concomitant decrease in high-density lipoprotein cholesterol (HDL-C)[ 51 ], as well as lowering blood pressure and improving insulin sensitivity[ 37 ]. Additional effects of the MD relate to its polyphenol content.…”

Diet and vascular risk

“…The evidence recently provided on the role of MedDiet in the control of nonalcoholic fatty liver disease (NAFLD) is particularly interesting since this metabolic disturbance leads to alterations in lipid metabolism and an increase in CV risk. The meta-analysis conducted by Kawaguchi et al [10 ▪▪ ] reported an improvement in hepatic steatosis and insulin resistance in patients with NAFLD with MedDiet consistent with another systematic review which showed that MedDiet has promising effects in NAFLD through antioxidant and anti-inflammatory effects [11 ▪▪ ]. All these effects support the positive impact of MedDiet on reducing CVD morbidity and mortality [12 ▪▪ ].…”

The Troubling Link Between Non-alcoholic Fatty Liver Disease (NAFLD) and Extrahepatic Cancers (EHC)

“…The effects of bariatric surgery can be mimicked by the very low-calorie diet (VLCD) as shown by the DIRECT trial [94]. Adapting to a Mediterranean diet is a viable option to prevent and treat NAFLD [95]. GLP-1 receptor agonists such as liraglutide [96] and semaglutide [97] can produce up to 10%-15% weight loss and are increasingly used to manage NAFLD [98].…”