Published online Jan 28, 2018. doi: 10.3748/wjg.v24.i4.445
Peer-review started: November 29, 2017
First decision: December 13, 2017
Revised: January 8, 2018
Accepted: January 16, 2018
Article in press: January 16, 2018
Published online: January 28, 2018
Core tip: Vitamin D deficiency is common and associated with chronic liver diseases. Several studies have ascribed a strong association of vitamin D insufficiency with unfavorable clinical courses and progression of liver disease in hepatitis B virus (HBV) and hepatitis C virus (HCV) infections. However, any causal relation is so far not fully understood. In addition, there are inconsistent results with regard to the impact of vitamin D supplementation on the virological response to IFN-based therapy; this applies particularly to HCV infections. The present review addresses general aspects of vitamin D deficiency and focuses on its association with HBV and HCV infection. Furthermore, the effects of vitamin D supplementation in combination with IFN-based therapy on the virological response in HBV and HCV infected patients are reviewed.