Irritable bowel syndrome (IBS) is a prevalent and complex gastrointestinal disorder characterized by chronic abdominal pain and altered bowel habits. Observational studies have suggested a relationship between serum Vitamin D levels and IBS symptoms. This systematic review and meta-analysis aimed to investigate the clinical effects of Vitamin D supplementation on IBS symptom severity and quality of life measures.
Medline, Embase, Scopus, Web of Science, and The Cochrane Library databases were systematically searched. Data abstraction and quality assessment were conducted by four authors independently and discrepancies were resolved through consensus from the senior author. Continuous data were pooled with standardized mean difference (SMD) using the DerSimonian and Laird’s random-effects model. Sensitivity analysis by risk of bias and potentially ‘predatory’ publication were performed as well RESULTS: A total of 685 patients across eight studies were included in the meta-analysis. Vitamin D supplementation significantly improved IBS Symptom Severity Scale (IBS-SSS) scores, with a SMD of -0.77 (95% CI -1.47 to -0.07, p = 0.04, I = 91%). Improvements in IBS-QOL scores were also observed, albeit not statistically significant (SMD 0.54; 95% CI -0.34 to 1.41, p = 0.15, I = 87%). However, small sample sizes, a relatively young study population, limited ethnicities and varied Vitamin D dosing strategies across the studies were notable limitations.
Vitamin D supplementation could be part of our clinical armamentarium when managing IBS patients due to the potential efficacy and good safety profile. Further randomized, controlled trials are required to confirm the therapeutic effects.

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