Effects of different dietary interventions on non-alcoholic fatty liver disease.

Many nutrients and the overall dietary composition can influence liver function. In fact, an excessive intake of refined carbohydrate and saturated fats, an increased consumption of fructose and other simple sugars, and the spread of high-calorie Western diets have been associated with a dramatic increase in overweight/obesity and insulin resistance and, more recently, also with non-alcoholic fatty liver disease (NAFLD). Noteworthy, the excess of adiposity, in particular abdominal adiposity, and insulin resistance are the major contributors to the development of several cardiometabolic abnormalities strictly related to the increased risk of cardiovascular disease (CVD) and type 2 diabetes mellitus (T2DM). Recently, considerable interest has been placed on the possible beneficial effect of some dietary components on NAFLD. Generally, hypercaloric diets, especially rich in trans/saturated fat and cholesterol, high consumption of red and processed meat, and fructose-sweetened beverages seem to increase the risk of NAFLD development, whereas a high consumption of foods or beverages rich in bioactive compounds of plant origin, such as whole grains, legumes, fruits, vegetables, nuts, coffee and tea, have shown preventive and therapeutic effects on NAFLD. The relationship between the intake of some dietary components and the improvement in NAFLD could be related, at least in part, to some bioactive compounds able to improve glucose and lipid metabolism, insulin resistance, hepatic fat content, sub-clinical inflammatory status, and oxidative stress. Consequently, it is conceivable that the combination of these foods in a dietary model such as a "Portfolio diet", inspired to a Mediterranean Diet model in which more beneficial dietary component are included – i.e. low glycemic index (GI) carbohydrates, vegetable fiber, monounsaturated fatty acids (MUFA), n-6 and n-3 polyunsaturated fatty acids (PUFA), polyphenols, and vitamins – could maximize the impact on prevention and treatment of NAFLD. In this scenario, it is important to define which dietary components are able to prevent and treat NAFLD to design dietary interventions to test. Therefore, the present project was designed to assess: (1) the relationships between liver fat content and metabolic, inflammatory and nutritional factors in a homogeneous cohort of individuals at high cardio-metabolic risk; (2) the effects of fructose intake on liver fat content and other cardiometabolic risk factors in a large cohort of abdominally obese men; (3) the effects of a Portfolio diet versus an isoenergetic diet rich in MUFA on liver fat content in patients with T2DM.