Effectiveness of vitamin D supplementation in managing urinary incontinence and overactive bladder: a systematic review and meta-analysis

Background: urinary incontinence (UI) and overactive bladder (OAB) are common lower urinary tract symptoms that significantly impact quality of life. Conventional pharmacologic treatments are often associated with side effects and limited efficacy, highlighting the need for alternative therapies. Vitamin D, known for its role in muscle function and its presence in the receptors of the bladder and prostate, has been proposed as a potential non-invasive intervention. This study aimed to evaluate the effectiveness of vitamin D supplementation in the management of UI and OAB. Methods: a systematic review and meta-analysis were conducted in accordance with the PRISMA guidelines. Twelve studies (six RCTs and six cohort studies) were included. Study quality was assessed using the Newcastle-Ottawa Scale (NOS) and the Cochrane Risk of Bias Tool. Statistical analysis was conducted using Review Manager 5.4. Standardized mean differences (SMDs) and risk ratios (RRs) were used to compare outcomes. A meta-analysis was performed using a random-effects model, which was applied due to heterogeneity, as assessed by the I² statistic. Sensitivity analysis was performed using the leave-one-out method. Results: no significant difference was found between the vitamin D and control groups in improving UI scales (SMD = -1.04; 95% CI: -2.35 to 0.27, p=0.12) with an I² of 94%. There were no significant effects on the risk of OAB (RR = 1.03, p=0.16) or UI (RR = 0.88, p=0.59), nor on UI improvement or worsening. The sensitivity analysis revealed that excluding one unusual study resulted in more consistent results and confirmed similar patterns. Conclusions: no substantial advantage of vitamin D was observed in UI or OAB patients compared to the control groups.