Effect of Vitamin D Supplementation on Metabolic Parameters in Patients with Metabolic-Associated Fatty Liver...

Vitamin D supplementation has been proposed as a therapeutic strategy for metabolic dysfunction-associated fatty liver disease (MAFLD); however, clinical evidence remains conflicting.

The aim of this investigation was to ascertain the efficacy of vitamin D treatment in managing MAFLD.

We searched PubMed, EMBASE, Web of Science, and the Cochrane Library, extending until April 2025. After analyzing and screening 2123 studies, 21 studies meeting the eligibility criteria for meta-analysis were selected. A random-effects model was used to determine the mean change in the standard mean difference for various variables, including insulin, fasting blood glucose (FBG), homeostasis model assessment of insulin resistance (HOMA-IR), high-density lipoprotein (HDL) cholesterol, low-density lipoprotein (LDL) cholesterol, total cholesterol (TC), triglycerides (TG), alanine aminotransferase (ALT), and aspartate aminotransferase (AST). Heterogeneity was assessed using I² in the analysis, and subgroup analysis was conducted to identify the sources of heterogeneity.

Pooled analysis demonstrated that vitamin D supplementation significantly reduced: FBG concentrations [-0.21; 95% confidence interval (CI): -0.41, -0.02], insulin (-0.60, 95% CI: -1.15, -0.05), HOMA-IR (-0.70; 95% CI: -1.23, -0.17), TG (-0.32; 95% CI: -0.60, -0.05), and ALT (-0.50; 95% CI: -0.90, -0.11), whereas increasing HDL cholesterol (0.30; 95% CI: 0.01, 0.59). However, vitamin D supplementation did not show a significant effect on TC (-0.28; 95% CI: -0.61, 0.05), AST (-0.29; 95% CI: -0.60, 0.02), or LDL cholesterol (-0.17; 95% CI: -0.41, 0.07).

The findings of this study indicate that vitamin D supplementation exerts a positive impact on carbohydrate and lipid metabolism, specifically in terms of FBG, insulin, HOMA-IR, TG, HDL cholesterol, and ALT concentrations among patients with MAFLD. Therefore, vitamin D could serve as an adjunctive therapy for fatty liver management in this patient population. The protocol for this study has been registered with PROSPERO as CRD42023457081.