The Mediterranean dietary pattern as the diet of choice for non‐alcoholic fatty liver disease: Evidence and plausible mechanisms

Abstract

Non-alcoholic fatty liver disease (NAFLD) has become a major global health burden, leading to increased risk for cirrhosis, hepatocellular carcinoma, type-2 diabetes and cardiovascular disease. Lifestyle intervention aiming at weight reduction is the most established treatment. However, changing the dietary composition even without weight loss can also reduce steatosis and improve metabolic alterations as insulin resistance and lipid profile. The Mediterranean diet (MD) pattern has been proposed as appropriate for this goal, and was recommended as the diet of choice for the treatment of NAFLD by the EASL-EASD-EASO Clinical Practice Guidelines. The MD has an established superiority in long term weight reduction over low fat diet, but it improves metabolic status and steatosis even without it.However, the effect on liver inflammation and fibrosis was tested only in few observational studies with positive results. Furthermore, considering the strong association between NAFLD and diabetes and CVD, the MD has a highly established advantage in prevention of these diseases, demonstrated in randomized clinical trials. The individual components of the MD such as olive oil, fish, nuts, whole grains, fruits, and vegetables, have been shown to beneficially effect or negatively correlate with NAFLD, while consumption of components that characterize a Western dietary pattern as soft drinks, fructose, meat and saturated fatty acids have been shown to have detrimental association with NAFLD. In this review we will cover the epidemiological evidence and the plausible molecular mechanisms by which the MD as a whole and each of its components can be of benefit in NAFLD.

Ad Libitum Mediterranean and Low‐Fat Diets Both Significantly Reduce Hepatic Steatosis: A Randomized Controlled Trial

“…In addition, the MD has high levels of polyphenols found in fruit and vegetables and high levels of monounsaturated fats found in olive oil. These compounds have been implicated in having wide‐ranging benefits, including inhibiting de novo hepatic lipogenesis, improving peripheral insulin sensitivity, and reducing CVR . Thus, there is potential for significant improvement in HS in the absence of significant weight loss in patients with NAFLD and for preferential improvements in cardiometabolic risk with the MD.…”

“…(35,36) Both groups also significantly increased dietary fiber consumption, which has been associated with reduced hepatic fat. (37) The increase in total fiber and the concomitant increase in prebiotic factors within the diet may also influence the microbiota and therefore gut-liver axis, which is implicated in NAFLD development and progression. (37,38) In addition, the MD has high levels of polyphenols found in fruit and vegetables and high levels of monounsaturated fats found in olive oil.…”

Association of dietary macronutrient composition and non-alcoholic fatty liver disease in an ageing population: the Rotterdam Study

“…Current dietary recommendations include caloric restriction and adherence to the macronutrient composition of the Mediterranean diet 7. However, evidence on the mono-unsaturated fatty acid (MUFA)–rich Mediterranean diet for NAFLD is limited by small study populations (n=12–90 subjects), suboptimal nutritional analyses or use of surrogate primary endpoints (ie, liver transaminases) rather than imaging diagnosis of NAFLD 11. Moreover, health recommendations on fat and carbohydrate consumption have been widely debated 12 13.…”

Ad Libitum Mediterranean or Low‐Fat Diets as Treatments for Nonalcoholic Fatty Liver Disease?

“…Considering the current evidence, recommending the MD for patients with NAFLD might be an appropriate therapeutic option, not least because patients with NAFLD are at increased risk of CVD . However, the evidence that the MD is beneficial in NAFLD is based on a few observational studies and small, short‐term RCTs . Currently, the MD is also recommended by the EASL–EASD–EASO Clinical Practice Guidelines for NAFLD (Grade, B1) .…”

“…Currently, the MD is also recommended by the EASL–EASD–EASO Clinical Practice Guidelines for NAFLD (Grade, B1) . The MD is particularly attractive in NAFLD given that it may benefit the liver, independently of concomitant weight loss …”