The effects of vitamin D supplementation on metabolic profiles and liver function in patients with non-alcoholic fatty liver disease: A systematic review and meta-analysis of randomized controlled trials

Background: A systematic review and meta-analysis of randomized controlled trials (RCTs) was conducted to summarize the evidence on the effect of vitamin D supplementation on metabolic profiles in patients with non-alcoholic fatty liver disease (NAFLD). Methods: We systematically searched PubMed, EMBASE and five other databases to identify all RCTs investigating the association between vitamin D and NAFLD up until 5 October 2016. Seven RCTs with 452 participants (227 patients and 225 controls) were included in the meta-analysis. Results: The results showed that vitamin D administration had no beneficial effect on fasting plasma glucose (FPG) (standardized mean difference [SMD]-0.23; 95% confidence interval [CI], -0.88, 0.42), insulin (SMD - 1.09; 95% CI, - 2.70,0.52) and homeostasis model assessment of insulin resistance (HOMAIR) (SMD - 1.89; 95% CI, - 3.88,0.09). Vitamin D supplementation also had no effect on lipid profiles including triglycerides (SMD - 0.36; 95% CI, - 1.77, 1.04), and total-cholesterol (SMD - 0.46; 95% CI: - 1.3, 0.39), as well as on aspartate transaminase (AST) (SMD - 0.53; 95% CI, - 1.11, 0.05), alanine aminotransferase (ALT) (SMD - 0.66; 95% CI, - 1.43,0.11), and body mass index (BMI) (SMD - 0.25; 95% CI, - 0.76,0.27). Conclusions: Vitamin D supplementation had no effect on FPG, insulin, HOMA-IR, triglycerides, total-, LDL-cholesterol, AST, ALT, and BMI. (C) 2017 Diabetes India. Published by Elsevier Ltd. All rights reserved.