(P03-006-24) A Systematic Review and Meta-Analysis of Vitamin D Intakes and Status in Adults With Irritable Bowel Syndrome

Objectives: Emerging research has suggested adequate vitamin D intake and/or status may be associated with improvements in Irritable Bowel Syndrome (IBS) symptoms and severity. This systematic review aimed to identify if changes in vitamin D intake or status affect symptom severity and quality of life in adults with IBS.

Methods: We searched five bibliographic databases from inception to 9 Dec 2023 for clinical trials, prospective cohort studies, and Mendelian randomization (MR) analyses that evaluated the effect of vitamin D intake or status on IBS-related outcomes in adults with IBS (protocol: PROSPERO CRD42023492631). When data were sufficient, we conducted random effects meta-analyses for quantitative results from randomized controlled trials (RCTs). Nutrition Quality Evaluation Strengthening Tools were used to assess risk of bias in RCTs.

Results: From 804 screened records, 15 articles reporting on 12 studies were included (n = 7 RCTs; n = 3 single arm interventions; n = 2 MR). When reported, study populations had deficient ( < 20 ng/mL, n = 9) and insufficient (21-29 ng/mL, n = 4) baseline serum 25-hydroxyvitamin D [25(OH)D] status. Most RCTs measured change in serum 25(OH)D levels and scores from the IBS Symptom Severity Scale and IBS Quality of Life Instrument. Supplementation ranged from 3,000 IU daily to 50,000 IU bi-weekly, and studies lasted 6 to 26 weeks. Risk of bias was low (n = 6) or neutral (n = 1). Meta-analyses of low risk-of-bias RCTs revealed increased 25(OH)D levels in groups treated with oral vitamin D, compared to the placebo (n = 5 studies; Pooled mean diff. [95% CI]: 20.33 [12.91, 27.74] ng/mL; I² = 97.9%). A non-significant decreased trend in IBS symptom severity was shown across populations, regardless of vitamin D status (n = 6: -25.89 [-55.26, 3.48]; I² = 92.8%), and among vitamin D deficient populations (n = 4: -31.22 [-65.61, 3.18]; I² = 94.8%). Quality of life scores improved significantly only in vitamin D deficient populations (n = 3; 3.02 [1.97, 4.07]; I² = 0.0%). Two-sample MRs reported mixed results (negative and null) between genetically determined vitamin D status and risk of IBS.

Conclusions: Treatment with vitamin D improved status in adults with IBS. Quality of life improved in those deficient at baseline, however, IBS symptom severity was not significantly different. Heterogeneity was high across studies.

Funding Sources: Nestlé Health Science