The Association Between Vitamin D and Irritable Bowel Syndrome: A Meta-Analysis of Randomized Controlled Trials and Observational Studies

This meta-analysis aimed to evaluate the effects of vitamin D supplementation on irritable bowel syndrome (IBS) symptoms and serum 25-hydroxy vitamin D 25(OH)D levels by synthesizing data from randomized controlled trials. Additionally, it aimed to compare baseline serum 25(OH)D levels between healthy individuals and IBS patients. The study is a meta-analysis of randomized controlled trials (RCTs) and observational studies. In the study conducted in accordance with PRISMA guidelines, 11 studies were evaluated and IBS-SSS, IBS-QoL and serum 25(OH)D levels were examined. Data were analyzed using the I² test to assess heterogeneity. The meta-analysis results showed that vitamin D supplementation improved the quality of life of IBS patients (mean difference [MD] for IBS-QoL: 6.48, 95% CI: 1.14-11.83, p=0.02). However, it had no significant effect on IBS symptom severity (IBS-SSS) (MD: 3.91, 95% CI: -60.99-68.81, p=0.91). Serum 25(OH)D levels were significantly increased by vitamin D supplementation (MD: 17.13, 95% CI: 8.09-26.17, p<0.0002). When serum 25(OH)D levels were compared between healthy individuals and IBS patients, a significant decrease was observed in IBS patients (standard mean difference [SMD]: -10.17, 95% CI: -15.57 to -4.77, p=0.0005). Vitamin D supplementation may be effective in improving quality of life and increasing serum vitamin D levels in IBS patients. However, more homogeneous and large-scale studies are needed to clarify its effect on symptom severity. These results provide a valuable perspective on the role of vitamin D supplementation in the management of IBS.