Vitamin D and Metabolic Dysfunction-Associated Fatty Liver Disease (MAFLD): An Update

Abstract

Non-alcoholic fatty liver disease (NAFLD) is the first cause of chronic liver disease worldwide; it ranges from simple steatosis to steatohepatitis (NASH) and, potentially, cirrhosis and hepatocarcinoma. NAFLD is also an independent risk factor for type 2 diabetes, cardiovascular diseases, and mortality. As it is largely associated with insulin resistance and related disorders, NAFLD has been recently re-named as Metabolic dysfunction-Associated Fatty Liver Disease (MAFLD). At present, there are no approved pharmacological treatments for this condition. Vitamin D is a molecule with extensive anti-fibrotic, anti-inflammatory, and insulin-sensitizing properties, which have been proven also in hepatic cells and is involved in immune-metabolic pathways within the gut–adipose tissue–liver axis. Epidemiological data support a relationship hypovitaminosis D and the presence of NAFLD and steatohepatitis (NASH); however, results from vitamin D supplementation trials on liver outcomes are controversial. This narrative review provides an overview of the latest evidence on pathophysiological pathways connecting vitamin D to NAFLD, with emphasis on the effects of vitamin D treatment in MAFLD by a nonsystematic literature review of PubMed published clinical trials. This article conforms to the Scale for Assessment of Narrative Review Articles (SANRA) guidelines. Evidence so far available supports the hypothesis of potential benefits of vitamin D supplementation in selected populations of NAFLD patients, as those with shorter disease duration and mild to moderate liver damage.

Association between serum 25-hydroxy vitamin D level and metabolic associated fatty liver disease (MAFLD)—a population-based study

“…This result was in line with previous studies that the lower serum 25(OH)D level increased the risk of NAFLD [5,6]. Vitamin D may influence the development of MAFLD in both direct and indirect manners, including the impact on systemic and hepatic inflammation, the maintenance of insulin sensitivity, and the controlling microenvironment by suppressing adaptive immunity and up-regulating innate immunity [20]. The vitamin D supplementation can reduce liver steatosis and improve adipose tissue inflammation on animal model [21].…”

Correlational study on the levels of 25-hydroxyvitamin D and non-alcoholic fatty liver disease in type 2 diabetic patients

“…participates in the occurrence and development of chronic liver diseases [ 11 ]. Ding et al [ 12 ] conducted basic research on vitamin D receptor knockout mice and found that it could spontaneously produce liver injury and liver fibrosis.…”

Serum Gamma Glutamyltransferase Is Associated with 25-Hydroxyvitamin D Status in Elderly Patients with Stable Coronary Artery Disease

“…Significant reductions in serum alkaline phosphatase and GGT were observed with vitamin D and calcitriol supplementation from baseline levels; however, no beneficial effect was noted when comparing vitamin D, calcitriol, and placebo groups at the end of the study. Available data support the hypothesis of the potential benefits of vitamin D supplementation in selected populations of NAFLD patients, such as those with shorter disease duration and mild to moderate liver damage [45].…”