The effects of vitamin D intake and status on symptom severity and quality-of-life in adults with irritable bowel syndrome (IBS): a systematic review and meta-analysis.

IMPORTANCE

Many individuals with irritable bowel syndrome (IBS) have insufficient or deficient serum 25-hydroxyvitamin D [25(OH)D] status; however, it is not clear if improved vitamin D nutritional status through higher intake can improve symptom severity and quality of life.

OBJECTIVE

This systematic review and meta-analysis aimed to identify if changes in vitamin D intake or status affect symptom severity and quality of life in adults with IBS. MEDLINE, Cochrane Central Register of Controlled Trials, Global Health, EMBASE, and Web-of-Science databases were systematically searched for relevant articles to August 12, 2024, in the English language. Clinical trials, prospective observational studies, and Mendelian randomization (MR) analyses reporting the effect of vitamin D intake or status on IBS-related outcomes were included. Article review and data extraction were conducted by 2 authors following the PRISMA guidelines. Random effects meta-analyses and the Nutrition Quality Evaluation Strengthening Tools to assess risk of bias were employed for randomized controlled trials. Primary outcomes included measures of serum 25(OH)D status, symptom severity, and quality of life.

RESULTS

12 studies from 15 articles were included ( = 7 RCTs;  = 3 single-arm interventions;  = 2 MR). Seven study populations had deficient (<20 ng/mL) and three had insufficient (21-29 ng/mL) baseline serum 25(OH)D status. RCTs measured changes in serum 25(OH)D after 6-26 wks with 3,000 IU daily to 50,000 IU bi-weekly vitamin D dosages. Meta-analyses of low risk-of-bias RCTs revealed increased 25(OH)D levels in groups treated with oral vitamin D compared to placebo ( = 5; Pooled mean difference [95% CI]: 20.33 [12.91, 27.74] ng/mL; = 97.9%). Quality of life scores improved significantly in deficient populations ( = 3; 3.19 [2.14, 4.24]; = 0.0%). Non-significant decreased trends in IBS symptom severity were shown across populations ( = 6: -25.89 [-55.26, 3.48]; = 92.8%).

CONCLUSION

Moderate level evidence indicate vitamin D supplementation may improve status in adults with IBS and quality of life in those with deficient status at baseline.