Published online Feb 14, 2015. doi: 10.3748/wjg.v21.i6.1718
Peer-review started: August 28, 2014
First decision: September 15, 2014
Revised: October 25, 2014
Accepted: December 5, 2014
Article in press: December 8, 2014
Published online: February 14, 2015
Vitamin D through its active form 1a-25-dihydroxyvtamin D [1,25(OH)2D] is a secosteroid hormone that plays a key role in mineral metabolism. Recent years have witnessed a significant scientific interest on vitamin D and expanded its actions to include immune modulation, cell differentiation and proliferation and inflammation regulation. As our understanding of the many functions of vitamin D has grown, the presence of vitamin D deficiency has become one of the most prevalent micronutrient deficiencies worldwide. Concomitantly, non-alcoholic fatty liver disease (NAFLD) has become the most common form of chronic liver disease in western countries. NAFLD and vitamin D deficiency often coexist and epidemiologic evidence has shown that both of these conditions share several cardiometabolic risk factors. In this article we provide an overview of the epidemiology and pathophysiology linking NAFLD and vitamin D deficiency, as well as the available evidence on the clinical utility of vitamin D supplementation in NAFLD.
Core tip: Non-alcoholic fatty liver disease (NAFLD) is a multifactorial disease and its pathogenesis is closely linked to the metabolic syndrome. Vitamin D deficiency, which also shares similar associations with obesity and sedentary lifestyle, is often found together with NAFLD. As our understanding of the many functions of vitamin D has grown, emerging evidence points to a closely linked and potentially causative relationship between vitamin D deficiency and NAFLD. As such, vitamin D is now emerging as an immunomodulatory and anti-fibrotic agent. However, in order to implement clinical recommendations larger, randomized, placebo-control trials are required to better evaluate the efficacy of vitamin D replacement in NAFLD.