Vitamin D deficiency is highly prevalent in chronic liver disease. Although international
societies recommend vitamin D supplementation in cases of proven deficiency, the impact
of vitamin D on chronic liver disease remains uncertain.Our aim was to evaluate the
effects of vitamin D supplementation in patients with chronic liver disease by conducting
a systematic review and meta-analysis of randomized controlled trials (RCTs).We systematically
searched PubMed, EMBASE and the Cochrane Library on July 2, 2024.Our primary outcomes
involved survival, controlled attenuation parameter (CAP), liver stiffness measurement
(LSM), and effects on changes in liver enzymes. Secondary outcomes included lipid
profile and homeostasis model assessment of insulin resistance (HOMA-IR), among others.
The pooled risk ratio (RR), mean difference (MD), and corresponding 95% CIs were calculated
using the random-effects model.Forty-six RCTs were included, comprising 4084 patients.
When we compared the vitamin D group with the control, the RR for overall survival
was 1.14 (95% CI, 0.85-1.54; 4 RCTs) at 6 months and 0.99 (95% CI, 0.83-1.17; 4 RCTs)
at the 12-month follow-up. Vitamin D supplementation did not result in a lower CAP
(MD, -23.50 dB/m; 95% CI, -81.72 to 34.72; 3 RCTs) and LSM (MD, -0.65 kPa; 95% CI,
-1.98 to 0.68; 3 RCTs). A significant reduction in HOMA-IR was observed in the vitamin
D group (MD, -0.31; 95% CI, -0.62 to -0.01; 15 RCTs). Alanine aminotransferase (ALT)
(MD, -4.98 IU/L; 95% CI, -8.28 to -1.68; 24 RCTs), aspartate aminotransferase (AST)
(MD, -3.33 IU/L; 95% CI, -6.25 to -0.40; 23 RCTs), gamma-glutamyl transferase (GGT)
(MD, -5.14 IU/L; -6.40; -3.88; 11 RCTs), triglycerides (MD, -7.59 mg/dL; 95% CI, -15.09
to -0.81), and insulin (MD -0.79 μIU/L; 95% CI, -1.36 to -0.21) were significantly
reduced in the patients with vitamin D supplementation.Our results showed significantly
reduced ALT, AST, GGT, triglycerides, insulin, and HOMA-IR in the vitamin D-supplemented
group; however, the effect was modest. In addition, there were no differences in survival,
CAP, or LSM. Further RCTs with adequate power are warranted to clarify the results.PROSPERO
registration No. CRD42022370312.
