Vitamin D3 deficiency has been associated with the co-existence of many non-skeletal chronic pathologies (including obesity, type 2 diabetes, cardiovascular disease, several types of tumours and non-alcoholic fatty liver disease), suggesting the possibility that this vitamin can have multiple and beneficial pleiotropic effects in extra-skeletal contexts, thanks to the ubiquitous distribution of its specific receptor.
Non-alcoholic fatty liver disease (NAFLD) is one of these extra-skeletal chronic pathologies associated with low circulating vitamin D3 levels. This disease has been the focus of significant scientific research, especially in the last 6-7 years.
NAFLD includes a broad spectrum of liver pathologies characterised by an accumulation of triglycerides in the liver in subjects without excessive alcohol consumption. The range of these pathologies includes simple steatosis and non-alcoholic steatohepatitis (NASH), which can lead to cirrhosis and even to hepatocellular carcinoma. Today, NAFLD represents the most common form of chronic liver disease in western countries: it is estimated that it is present in roughly 25-30% of the general adult population. Globally, its prevalence is progressively increasing in many parts of the world, similar to what has been observed for the incidence of obesity and type 2 diabetes, two metabolic pathologies with which NAFLD is closely connected, as they represent the most important risk factors for the disease.