Effects of vitamin D supplementation on liver fibrogenic factors in non-alcoholic fatty liver patients with steatohepatitis: study protocol for a randomized clinical trial

Background It has been suggested that vitamin D and its receptors involve in suppressing fibrogenic signaling in non-alcoholic fatty liver disease (NAFLD). However, the effect of vitamin D supplementation on fibrogenic factors has not been investigated in NAFLD individuals with steatohepatitis. This study was designed to examine the effects on vitamin D supplementation on serum levels of vitamin D receptor (VDR), fibrogenic factors, and fibrogenic microRNAs (MiR) in NAFLD patients. Methods Forty-six NAFLD patients will be recruited in this study. After block matching for sex and BMI, they will be randomly assigned to receive 4000 IU/day vitamin D or placebo for 12 weeks. Weight, height, and waist circumference will be measured. Determination of serum fibrogenic MiRs, laminin, collagen type IV, hyaluronic acid, vitamin D, VDR, calcium, blood glucose, serum insulin, lipid profile, liver markers (ALT, AST, total, direct, and indirect bilirubin) will be done at study baseline and at the end of the trial. Insulin resistance and insulin sensitivity will be determined using the HOMA-IR and QUICKI equation. Discussion This is the first randomized controlled trial that will determine the effect of vitamin D supplementation on serum levels of VDR, fibrogenic factors, and fibrogenic MiRs in NAFLD patients. The results of this trial will provide clinical evidence on the effectiveness of vitamin D supplementation in controlling liver fibrosis in NAFLD patients. Trial registration Iranian Registry of Clinical Trials, IRCT201405251485N13. Registered on 14 March 2017. Electronic supplementary material The online version of this article (10.1186/s13063-019-3241-7) contains supplementary material, which is available to authorized users.