Review article: the extra-skeletal effects of vitamin D in chronic hepatitis C infection

Background Recent interest has focused on the extra-skeletal effects of vitamin D, in particular, in patients with chronic hepatitis C. Aims To review data in the literature regarding the extra-skeletal effects of vitamin D in patients with chronic hepatitis C, with and without liver transplantation. Methods A Medline search was performed for relevant studies up to August 2011 using the terms 'vitamin D' 'chronic liver disease' and 'hepatitis C'. Results Vitamin D deficiency is very frequent before liver transplantation ranging between 51% and 92%, whereas, in the liver transplantation setting, the prevalence of vitamin D deficiency is also high. Severe liver disease may increase the risk of vitamin D deficiency and vice versa, as there may be a relationship between vitamin D deficiency and fibrosis. In patients with chronic hepatitis C and those with recurrent of hepatitis C after liver transplantation, recent clinical data shows that a higher serum vitamin D level is an independent predictor of sustained virological response (SVR) following anti-viral therapy, and that a higher SVR is achieved with vitamin D supplementation. Conclusions Larger randomised clinical studies with adequate statistical power are needed to confirm these potentially very important nonskeletal effects of vitamin D in patients with chronic hepatitis C.