Alimentary regimen in non-alcoholic fatty liver disease: Mediterranean diet

Abstract

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease worldwide. The mechanisms of the underlying disease development and progression are awaiting clarification. Insulin resistance and obesity-related inflammation status, among other possible genetic, dietary, and lifestyle factors, are thought to play the key role. There is no consensus concerning the pharmacological treatment. However, the dietary nutritional management to achieve weight loss is an essential component of any treatment strategy. On the basis of its components, the literature reports on the effectiveness of the Mediterranean diet in reducing cardiovascular risk and in preventing major chronic diseases, including obesity and diabetes. New evidence supports the idea that the Mediterranean diet, associated with physical activity and cognitive behaviour therapy, may have an important role in the prevention and the treatment of NAFLD.

Keywords: Insulin resistance; Mediterranean diet; Non-alcoholic fatty liver disease; Non-alcoholic steatohepatitis; Nutrition.

Figure 1

Mechanisms involved in multistep pathogenesis of non-alcoholic fatty liver disease. The development of an inflammatory status and oxidative stress can induce fibrosis, necrosis and steato-hepatitis. Insulin resistance promotes the activation of cytochrome P450 2E1, that induces cellular higher levels of reactive oxygen species (ROS) and oxidative stress, determining lipid peroxidation leading to necrosis, and activation of stellate cells with liver fibrosis. The activation of Kuppfer cells by nuclear factor-kappaB (NF-κB) resulting in an increased production of inflammatory cytokines such as tumour necrosis factor-α (TNF-α), cyclooxygenase-2 (COX-2) and interleukin-6 (IL-6) that cause the development of an inflammatory status, steato-epatitis and improve the insulin resistance. MMP: Matrix metalloproteinases; TGF: Transforming growth factor; α-SMA: α-smooth muscle actin; LPS: Lipopolysaccharide; iNOS: Inducible nitric oxide synthase.

Figure 2

Traditional Mediterranean diet pyramid. The Mediterranean dietary plan emphasizes daily consumption of cereal, vegetables, bread, pasta, fruit, olive oil and dairy products. Eggs, sweets, fish, poultry, potatoes, pulses and nuts are recommended weekly, and red meat a few times per month and in a very small amount.