The effect of vitamin D supplementation on the liver function in non-alcoholic fatty liver disease patients: a systematic review and meta-analysis of randomized controlled trials
In brief
Vitamin D lowers ALT modestly and reduces ALP by ~13 IU/L in NAFLD
A meta-analysis of 16 randomized trials found that vitamin D supplementation modestly decreased ALT levels (standardized mean difference ≈ -0.45) and lowered alkaline phosphatase by about 13 units per liter, while showing no clear effect on AST or GGT. The results hint at a supportive role for vitamin D in NAFLD, but larger trials are needed to confirm clinical benefit.
- Journal
- Diabetology & metabolic syndrome (Q1)
- Published
- 13 July 2026
- Study design
- Systematic review / meta-analysis of RCTs
- Evidence level
- Level 1, High (CEBM 1a)
- Authors
- Mahdi Vajdi, Negin Nikrad, Mahsa Khajeh, Nooshin Noshadi, Mahsa Maroofi, Melika Darzi, et al.
- PMID
- 42443965
- DOI
- 10.1186/s13098-026-02225-w
Why clinicians should know about it
- Picked for Hepatology (top studies of the week, 19 July 2026): Vitamin D supplementation meta‑analysis on NAFLD liver function
- Picked for Internal Medicine (top studies of the week, 19 July 2026).
Abstract
BACKGROUND: Empirical studies examining the impact of vitamin D supplementation on the liver function in non-alcoholic fatty liver (NAFLD) disease patients have yielded incongruous outcomes. In this systematic review and meta-analysis of randomized controlled trials (RCTs), we investigated the effect of vitamin D supplementation on liver enzymes (alanine transaminase (ALT), aspartate aminotransferase (AST) and gamma-glutamyl transferase (GGT) and alkaline phosphatase (ALP)) in NAFLD patients. METHODS: A systematic literature search was conducted using scientific databases including PubMed/Medline, Embase, Web of Science, Cochrane library and Scopus, through May 2026. The search strategy included terms for the interventions (vitamin D, cholecalciferol, calcitriol) and outcomes (ALT, AST, ALP, and GGT) in NAFLD patients. Weighted/standardized mean differences (WMD, SMD) and 95% CI were analyzed utilizing a random-effects model. RESULTS: Overall, 16 RCTs met our inclusion criteria. The current meta-analysis demonstrates a significant reduction in ALT (SMD: -0.45; 95% CI: - 0.87 to -0.04; P = 0.032), and ALP (WMD: -12.91 IU/L; 95% CI: - 18.75 to -7.08; P < 0.001). However, analysis of studies indicated a non-significant effect on AST, GGT. Subgroup analysis showed that the effect of vitamin D on AST is more pronounced in studies with a dose ≤ 3500 IU/day, duration > 12 weeks and using cholecalciferol (as opposed to calcitriol). CONCLUSION: The findings of this study indicate that vitamin D supplementation may be associated with improvements in ALT and ALP levels, while no significant effects were observed for AST and GGT. These results suggest a possible beneficial role of vitamin D in supporting liver function among patients with NAFLD; however, the evidence remains inconclusive. Future studies are needed to investigate the effect of vitamin D on health status in in NAFLD patients. PROSPERO CODE: CRD42024545499.
Abstract as published, via PubMed.
For healthcare professionals. The summary is generated by AI from the published abstract, and the evidence level is assigned automatically from the study design on the Oxford CEBM hierarchy. Neither is medical advice. Read the full paper before changing practice.