Does the Mediterranean Diet Have Any Effect on Lipid Profile, Central Obesity and Liver Enzymes in Non-Alcoholic Fatty Liver Disease (NAFLD) Subjects? A Systematic Review and Meta-Analysis of Randomized Control Trials

Abstract

The effectiveness of the Mediterranean diet (MD) in non-alcoholic fatty liver disease (NAFLD) subjects has been evaluated in several randomized controlled trials (RCTs). This systematic review and meta-analysis aimed to evaluate the overall effects of MD intervention in a cohort of NAFLD patients targeting specific markers such as central obesity, lipid profile, liver enzymes and fibrosis, and intrahepatic fat (IHF). Google Scholar, PubMed, and Scopus were explored to collect relevant studies from the last 10 years. RCTs with NAFLD subjects were included in this systematic review with a mean intervention duration from 6 weeks to 1 year, and different intervention strategies, mainly including energy restriction MD (normal or low glycaemic index), low-fat MD with increased monounsaturated and polyunsaturated fatty acids, and increased exercise expenditure. The outcomes measured in this meta-analysis were gamma-glutamyl transferase (GGT), alanine aminotransferase (ALT), total cholesterol (TC), waist circumference (WC), and liver fibrosis. Ten randomized controlled trials, which involved a total of 737 adults with NAFLD, were included. According to the results, the MD seems to decrease the liver stiffness (kPa) by –0.42 (CI95% –0.92, 0.09) (p = 0.10) and significantly reduce the TC by –0.46 mg/dl (CI95% –0.55, −0.38) (p = 0.001), while no significant findings were documented for liver enzymes and WC among patients with NAFLD. In conclusion, the MD might reduce indirect and direct outcomes linked with NAFLD severity, such as TC, liver fibrosis, and WC, although it is important to consider the variations across trials. Further RCTs are necessary to corroborate the findings obtained and provide further evidence on the role of the MD in the modulation of other disorders related to NAFLD.

The Influence of Diet and Its Components on the Development and Prevention of Hepatocellular Carcinoma (HCC)

“…The Mediterranean diet (MD) is recommended as a dietary model in case of the need to improve liver parameters, the deterioration of which is observed among overweight individuals. Its adoption contributes to the reduction of inflammation, an improvement to liver stiffness parameters, a reduction in total cholesterol levels, and also a reduction in waist circumference [ 17 , 18 ]. The MD relies on the intake of primarily monounsaturated fatty acids through the use of olive oil, as well as the intake of polyunsaturated fatty acids through the consumption of fatty fish [ 17 ].…”

“…Its adoption contributes to the reduction of inflammation, an improvement to liver stiffness parameters, a reduction in total cholesterol levels, and also a reduction in waist circumference [ 17 , 18 ]. The MD relies on the intake of primarily monounsaturated fatty acids through the use of olive oil, as well as the intake of polyunsaturated fatty acids through the consumption of fatty fish [ 17 ]. These fatty acids are characterized by the suppression of pro-inflammatory cytokines, which are observed in MASLD.…”

“…These fatty acids are characterized by the suppression of pro-inflammatory cytokines, which are observed in MASLD. Other characteristic components of the MD include soluble fiber and bioactive compounds provided by vegetables and plant products [ 17 ]. It has been proven that a higher intake of dietary fiber is associated with a reduced risk of MASLD, while some of the bioactive compounds, by influencing metabolic processes, decrease de novo lipogenesis and enhance lipolysis, counteracting the development of disorders that gradually lead to HCC [ 17 ].…”

“…A diet to prevent the development of MASLD should regularly include vegetables, fruits, legumes, fiber-rich products, and sources of unsaturated fats [ 17 ]. Conversely, products rich in saturated fats, low-fiber products providing refined carbohydrates, and those with added fructose should be eliminated from the diet [ 17 ].…”

“…A diet to prevent the development of MASLD should regularly include vegetables, fruits, legumes, fiber-rich products, and sources of unsaturated fats [ 17 ]. Conversely, products rich in saturated fats, low-fiber products providing refined carbohydrates, and those with added fructose should be eliminated from the diet [ 17 ]. Therefore, to minimize the risk of HCC development, efforts should be directed towards maintaining proper body composition parameters and basic test results, such as in lipid profile and liver function tests, through adherence to the general principles of healthy nutrition [ 18 , 19 ].…”