Stesura Seveso Archivio Italiano di Urologia e Andrologia 2025; 97(3):14172 1 REVIEW INTRODUCTION Lower urinary tract symptoms (LUTS), including urgency, frequent urination, urinary incontinence (UI), and noc- turia, whether occurring individually or as part of a syn- drome known as overactive bladder (OAB), are prevalent and distressing conditions that affect millions of individ- uals worldwide (1-3). Epidemiological studies reveal that these symptoms impact 12% to 18% of community- dwelling men, with incidence increasing with age (2-4). Initial therapies for UI and OAB include non-invasive behavioral approaches and/or pharmacological treat- ments, tailored to the patient’s goals and preferences. Pharmacologic interventions are frequently commenced for particular OAB symptoms, such as urgency (with or without UI), frequency, and nocturia. However, recent findings indicate that pharmaceutical interventions, including anticholinergic bladder relaxants, are fre- quently abandoned due to unpleasant side effects or per- ceived ineffectiveness (4). Moreover, growing concerns have emerged regarding their potential long-term adverse effects on cognitive function (5). As a result, there is a clear need to develop alternative strategies that promote prevention and early intervention, particularly for men affected by UI and OAB. Vitamin D supplemen- tation has been proposed as a simple and potentially effective strategy for alleviating LUTS, especially storage problems associated with OAB. Vitamin D receptors are present in the detrusor muscle of the bladder and the prostate (6, 7), and vitamin D administration may enhance smooth and skeletal muscle performance while decreasing prostate growth (8, 9). Thus, vitamin D may contribute to improved bladder control by directly enhancing detrusor smooth muscle activity and reducing the sensation of urgency. However, the relationship between vitamin D and UI remains unclear, as research findings have been contra- dictory. 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 inter- vention. This study aimed to evaluate the effectiveness of vita- min D supplementation in the management of UI and OAB. Methods: A systematic review and meta-analysis were conduct- ed 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 vita- min 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 worsen- ing. The sensitivity analysis revealed that excluding one unusu- al study resulted in more consistent results and confirmed simi- lar patterns. Conclusions: I No substantial advantage of vitamin D was observed in UI or OAB patients compared to the control groups. KEY WORDS: Vitamin D; Urinary incontinence; Overactive bladder. Submtted 24 July 2025; Accepted 1 August 2025 Effectiveness of vitamin D supplementation in managing urinary incontinence and overactive bladder: A systematic review and meta-analysis Saad Thamer Alshahrani 1, Naif Alamri 2, Mohammad Dhafer Asiri 3, Meshal Omar Albabtain 4, Raed Alwadai 5, Hassan M. Assiri 1, Saleh Alghamdi 1, Ali Thamer Alshahrani 6, Mohanad Jebril Bosily 7, Hussain Munyif 8, Omar Safar 1 1 Urology Department, Armed Forces Hospital Southern Region, Khamis Mushayt, Saudi Arabia; 2 Urology Department, Saudi German Hospital, Asir, Saudi Arabia; 3 Urology Department, Health Cluster 1, Riyadh, Saudi Arabia; 4 Urology Department, King Saud Medical City, Riyadh, Saudi Arabia; 5 Urology Department, King Abdullah Hospital, Bisha, Asir, Saudi Arabia; 6 College of Medicine, King Khalid University, Abha, Saudi Arabia; 7 Ministry of Health, Aseer Health Cluster, Asir, Saudi Arabia; 8 Urology Department, King Khalid Hospital, Najran City, Saudi Arabia. DOI: 10.4081/aiua.2025.14172 Summary Archivio Italiano di Urologia e Andrologia 2025; 97(3):14172 S. Thamer Alshahrani, N. Alamri, M. Dhafer Asiri, et al. 2 Vitamin D is a lipophilic molecule mostly acquired by solar exposure or dietary consumption. Vitamin D attach- es to vitamin D-binding protein in the body and is metab- olized to 25-hydroxyvitamin D [25(OH)D] by 25-hydrox- ylase in the liver; its concentration is typically utilized to evaluate an individual's vitamin D status. In primary cul- tures of satellite cells, 1,25-dihydroxyvitamin D3 was observed to enhance myogenic differentiation and myotube formation by elevating the expression of myo- genic regulatory proteins, including myogenin (10). The research conducted by van der Meijden et al. (11) fur- ther demonstrated that higher levels of vitamin D support the differentiation and maturation of skeletal muscle cells, leading to increased myotube fiber diameter and enhanced muscle performance. These findings suggest a potential novel approach for treating UI. However, the relationship between vitamin D levels and urinary symp- toms remains unclear, with studies showing conflicting results. Therefore, this systematic review aims to evaluate the effectiveness of vitamin D supplementation in the management of OAB and UI. METHODS Study design The systematic review adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines (12). The Prospero registration number was given to the pro- tocol of this systematic review [CRD420251107352]. Definition of inclusion criteria and targeted outcomes The inclusion criteria focused on studies evaluating the effectiveness of vitamin D supplementation in managing overactive bladder (OAB) and urinary incontinence (UI). Eligible study designs included randomized controlled trials (RCTs) and cohort studies. The review was guided by the PICO framework, where the population consisted of patients with OAB or UI, the intervention involved vitamin D supplementation, and the comparator includ- ed placebo, no intervention, or lower doses of vitamin D, where applicable. The outcomes of interest were efficacy measures, particularly improvements in urinary symp- toms. Studies were excluded if they presented insufficient or unclear outcome data, or if they were laboratory-based studies, posters, study protocols, case studies, case series, case reports, abstract-only publications, reviews, or arti- cles not published in English. Search strategy A comprehensive search for systematic reviews was con- ducted across the following electronic databases for arti- cles published from inception to March 2025: PubMed, Cochrane Library, Scopus, and Web of Science. The search strategy employed a combination of keywords and Medical Subject Headings (MeSH) related to the PICO framework. Terms such as "Urinary incontinence", "Overactive bladder", and "Vitamin D" were combined using Boolean operators (AND/OR) to capture relevant studies. Filters were applied to include only English-lan- guage studies from the last 10 years and focus on specific study types, such as clinical trials, RCTs, and retrospec- tive studies, ensuring relevance to the research question. Additionally, reference lists of relevant articles were reviewed to ensure thorough coverage of the available evidence. Screening and extraction Initially, articles with irrelevant titles were excluded. In the subsequent phase, both the full text and abstracts of papers were meticulously reviewed to determine their compliance with the inclusion criteria. To streamline the process, titles and abstracts were organized and screened using EndNote version 8, and duplicate records were removed. The titles and abstracts were independently screened by two reviewers, followed by a full-text assess- ment based on predefined inclusion and exclusion crite- ria. Full-text articles meeting the inclusion criteria under- go further assessment. Baseline characteristics and out- come data were extracted in Excel sheets. Any differences of opinion were resolved by consensus or by referring them to a senior author. Quality assessment The Newcastle-Ottawa Scale (NOS) was used for non-ran- domized studies, including retrospective or prospective cohort designs. Scores were interpreted as low quality if they received 0-3 stars, moderate quality if they received 4-6 stars, and high quality if they received 7-9 stars (13). For randomized controlled trials (RCTs), the Cochrane Risk of Bias Tool was used. This tool systematically evaluated various domains of bias, including selection bias, per- formance bias, detection bias, attrition bias, and reporting bias. Each study was carefully reviewed to determine whether the authors had implemented adequate meas- ures to minimize these biases. Statistical analysis The statistical analysis was done using Review Manager 5.4 software. We compared the continuous outcomes using the standardized mean difference (SMD), given the difference in measurement scales. We compared the dichotomous data using the risk ratio (RR). Heterogeneity was assessed using I², with a p-value of 0.05. A random- effects model was used to account for the heterogeneity among the outcomes. Sensitivity analysis using the leave- one-out method was used to resolve the heterogeneity. All the steps were done at 95% confidence intervals (CI), and p-values were considered significant if they were less than or equal to 0.05. RESULTS Search results The searching process resulted in a total of 221 articles from the included databases. These encompassed 123 duplicates, so we conducted title and abstract screening on the remaining 98 articles. In this phase, 81 articles were excluded, and 17 were included for full-text screening, resulting in 12 articles Archivio Italiano di Urologia e Andrologia 2025; 97(3):14172 3 Vitamin D in urinary incontinence and overactive bladder being selected for the current systematic review and meta-analysis (Figure 1). Results of quality assessment The quality of the six included cohort studies was assessed using NOS, which evaluates studies based on three domains: selection of study groups (maximum four stars), comparability of groups (maximum two stars), and ascertainment of either the exposure or out- come (maximum three stars). Three studies - Vaughan (2021), Markland (2020), and Vaughan (2022) - received the highest overall rating of 9 stars, indicating strong methodological quality across all domains. These stud- ies achieved full scores in selection and outcome/expo- sure, and were rated with two stars in comparability, suggesting robust control of confounding variables. Özçift and Micoogullari (2022) and Yoo (2018) scored seven stars each, reflecting slightly lower quality due to limited comparability and fewer stars in the outcome domain. Aydogmus (2023) received the lowest rating of 5 stars, with limited strength in both selection and comparability domains. Overall, the majority of studies included in the review demonstrated moderate to high methodological quality, with careful selection and adequate outcome assessment; however, variation in the control for con- founding was noted (Table 1). The risk of bias across the six included RCTs was evaluat- ed using the Cochrane Risk of Bias tool, covering seven domains: random sequence generation, allocation con- cealment, blinding of participants and personnel, blinding of outcome assessment, incomplete outcome data, selec- tive reporting, and other bias. Shahraki (2022) demon- strated the highest methodological rigor, with a low risk of bias across all domains, indicating strong internal validity. Markland (2023) and Markland (2022), although showing Figure 1. PRISMA flow diagram of searching and screening processes. Archivio Italiano di Urologia e Andrologia 2025; 97(3):14172 S. Thamer Alshahrani, N. Alamri, M. Dhafer Asiri, et al. 4 low risk in most categories, exhibited high risk of bias in selective reporting and other biases, potentially affecting the reliability of their outcomes. Markland (2019) showed a low risk in most areas, but allocation concealment was unclear, which slightly weakened its overall robustness. Arjmand (2023) had unclear risk in three domains – allo- cation concealment, blinding of participants and person- nel, and outcome assessment – raising concerns about potential performance and detection bias. The Oberg (2017) study had multiple areas of concern, including unclear randomization, allocation, and per- formance blinding, as well as a high risk of bias in out- come assessment, indicating a greater potential for bias. Overall, while several studies were methodologically sound, a few showed risks, particularly in blinding and reporting, that should be considered when interpreting their findings (Table 2). Baseline characteristics The baseline characteristics of the included studies reveal a diverse representation of populations across various countries and age groups, focusing on the relationship between vitamin D supplementation and UI or OAB symptoms. Six studies were RCTs and six were cohort studies. Study populations ranged from children [mean age 7.71 years (14)] to older adults [mean age 71.6 years (15)], with sample sizes varying widely from small ran- domized controlled trials [e.g., 30 participants per arm (16)] to large cohort studies [e.g., 59355 participants (17)]. Most studies focused on women, with several tar- geting postmenopausal women or those with specific UI subtypes, while a few included men (18, 19). The inter- ventions involved varying doses and forms of vitamin D, from low daily doses to high-dose regimens such as 50,000 IU weekly (20) or a single intramuscular dose of 200,000 IU (21). Control groups primarily received placebos, no interven- tion, or lower doses of vitamin D. Collectively, the base- line characteristics underscore substantial heterogeneity in study design, intervention protocols, control group, and target demographics (Table 3). Statistical analysis No significant difference was observed between vitamin D and the control groups regarding the effect on UI scales with SMD = -1.04 (95% CI: -2.35, 0.27, p = 0.12) and I2 = 94%, p < 0.00001 (Figure 2). No significant difference was observed between vitamin D and controls regarding the risk of OAB (RR: 1.03; 95% CI: 0.99 to 1.07, p = 0.16, and I2 = 45%, p = 0.16) and UI (RR: 0.88; 95% CI: 0.57 to 1.37, p = 0.59, and I2 = 93%, p < 0.00001) (Figures 3, 4). No significant difference was observed between vitamin D and control in UI improvement (RR: 1.57, 0.31, 7.78, p = 0.58, and I2 = 76%, p = 0.04) or worsening (RR: 1.37; 95%CI: 0.82, 2.3, p = 0.23, and I2 = 96%, p < 0.00001) (Figures 5, 6). Sensitivity analysis Sensitivity analysis using the leave-one-out method revealed that removing Shahraki 2022 (4) (high control values) resolved the heterogeneity in the UI scales, with SMD = -0.34 (95% CI: -0.9, 0.21, p = 0.23) and I² = 55%, p = 0.14. (Figure 7). Table 2. The Cochrane risk of bias assessment for RCT. Study Random Allocation Blinding Blinding Incomplete Selective Other sequence concealment of participants of outcome outcome reporting bias generation and personnel assessment data Arjmand 2023 (7) Low Unclear Unclear Unclear Low Low Low Markland 2023 (8) Low Low Low Low Low High High Shahraki 2022 (9) Low Low Low Low Low Low Low Markland 2019 (10) Low Unclear Low Low Low Low Low Oberg 2017 (11) Unclear Unclear Unclear High Low Low Unclear Markland 2022 (12) Low Low Low Low Low High High Table 1. The NOS quality assessment for non-randomized studies. Studies Selection Comparability Exposure/Outcome Overall star rating Aydogmus 2023 (1) ** * ** 5 Vaughan 2021 (2) **** ** *** 9 Markland 2020 (3) **** ** *** 9 Özçift and Micoogullari 2022 (4) **** * ** 7 Yoo 2018 (5) *** ** ** 7 Vaughan 2022 (6) **** ** *** 9 Archivio Italiano di Urologia e Andrologia 2025; 97(3):14172 5 Vitamin D in urinary incontinence and overactive bladder Table 3. Baseline characteristics of the included studies. Study ID Study Population Country Study Intervention Control Sample size Mean Age, (SD) Male, n (%) Dose of design period Intervention Control Intervention Control Intervention Control Vitamin D Arjmand 2023 (7) RCT Postmenopausal women Iran 2019–2020 Vitamin D Placebo 45 45 58 (5) 57 (5) 0 (0) 0 (0) Vitamin D3 with urgency urinary (50,000 IU) tablets incontinence weekly for 8 weeks Aydogmus 2023 (1) Cohort Postpartum urinary Pelvic floor incontinence Belgium NR Vitamin D muscle 29 28 27.8 (5.9) 27.4 (4.6) 0 (0) 0 (0) 1200 IU daily training group vitamin D for 12 weeks Markland 2023 (8) RCT Older men with overactive USA Between November Vitamin D Placebo 2823 2830 68 (7) 68 (7) 2823 (100) 2830 (100) Vitamin D3 2000 IU bladder and urinary 2011 and March incontinence symptoms 2014 Shahraki 2022 (9) RCT Premenopausal women Iran 2020 and 2021 Vitamin D Placebo 30 30 44.53 (2.5) 44.23 (2.4) 0 (0) 0 (0) 5000 IU vitamin D with stress urinary incontinence weekly for 3 months and vitamin D insufficiency Markland 2019 (10) RCT Women with urgency USA From 2013–2017 Vitamin D Placebo 28 28 61.4 (7.1) 59.5 (9.2) 0 (0) 0 (0) Weekly oral 50,000 urinary incontinence IU vitamin D3 for 12 weeks Vaughan 2021 (NHS-I) (2) Cohort Women with urinary USA 2004–2012 >=1000 IU 0–<200 IU vitamin D 2213 3063 71.6 (6.78) 70.72 (7) 0 (0) 0 (0) 0-200 IU or >=1000 IU incontinence vitamin D intake intake daily vitamin D intake Vaughan 2021 (NHS-II) (2) Cohort Women with urinary USA 2005–2013 >=1000 IU 0–<200 IU vitamin D 1082 2669 52.97 (4.09) 50.53 (4.53) 0 (0) 0 (0) 0-200 IU or incontinence vitamin D intake intake >=1000 IU daily vitamin D intake Markland 2020 (NHS-I) (3) Cohort Women with urgency urinary USA 2004–2012 >=1000 IU 0–<200 IU vitamin D 3912 6472 68 (7) 67 (7) 0 (0) 0 (0) 0-200 IU or >=1000 IU daily incontinence vitamin D intake intake vitamin D intake Markland 2020 (NHS-II) (3) Cohort Women with urgency urinary USA 2005–2013 >=1000 IU vitamin D 0–<200 IU vitamin D 2956 7555 52 (4) 49 (5) 0 (0) 0 (0) 0-200 IU or >=1000 IU daily incontinence intake intake vitamin D intake Oberg 2017 (11) RCT Postmenopausal women Norway 2007-2010 High dose vitamin D Standard dose 134 139 62.8 (7.5) 63.4 (6.9) 0 (0) 0 (0) 20000 IU daily in the high with lower urinary tract symptoms vitamin D dose group and 400 IU of vitamin D3 twice daily in the standard dose group Özçift and Micoogullari 2022 (4) Cohort Children with overactive bladder Turkey Between May Vitamin D NA 34 NA 7.71 (2.66) NA 16 (48) NA Oral vitamin D3 2000 IU/day related urinary incontinence 2017 and July 2021 was pres cribed for 8 weeks Yoo 2018 (5) Cohort Men with lower urinary tract Korea Between March 2014 Vitamin D NA 255 NA 59.4 (11.4) NA 255 (100) NA Intramuscular injection symptoms and April 2017 of 200000 IU in a single dose Vaughan 2022 (6) Cohort Women from mid-life through USA NR Vitamin D (>=1000 IU) No vitamin D 36789 22566 67 (6.5) 67 (6.9) 0 (0) 0 (0) >=1000 IU older ages with overactive bladder Markland 2022 (12) RCT Older women with urinary USA 2011 to 2018 Vitamin D Placebo 5213 5222 70 (7) 70 (7) 0 (0) 0 (0) 2000 IU/day incontinence NA: not applicable; RCT: Randomized controlled trial. Figure 2. Comparison between vitamin D and controls in their effect on urinary incontinence scales. Archivio Italiano di Urologia e Andrologia 2025; 97(3):14172 S. Thamer Alshahrani, N. Alamri, M. Dhafer Asiri, et al. 6 Figure 3. Comparison between vitamin D and controls in the risk of overactive bladder. Figure 4. Comparison between vitamin D and controls in the risk of urinary incontinence. Figure 5. Comparison between vitamin D and controls in urinary incontinence improvement. Figure 6. Comparison between vitamin D and controls in urinary incontinence worsening. Figure 7. Leave-one-out analysis of the comparison between vitamin D and controls in their effect on urinary. Archivio Italiano di Urologia e Andrologia 2025; 97(3):14172 7 Vitamin D in urinary incontinence and overactive bladder DISCUSSION Summary of findings This systematic review and meta-analysis examined the potential effect of vitamin D supplementation in alleviat- ing symptoms of UI and OAB. The study encompassed a diverse population, including children, postpartum women, postmenopausal women, and elderly individu- als of both genders. This demonstrated the diversity of the impacted groups. In the comparison of vitamin D supplementation against a placebo or other control cir- cumstances for its effect on urinary symptoms, no statis- tically significant changes were observed. Nonetheless, an examination of scores before and during therapy revealed a persistent tendency toward enhancement among the intervention groups. The analysis of risk ratios did not demonstrate that vitamin D supplementa- tion significantly decreased or increased the likelihood of developing UI or OAB. The comparisons of the improve- ment or worsening of symptoms revealed no significant differences between the vitamin D group and the control group. Nonetheless, considerable variability existed among the studies, likely because of the extensive range of dosages, methods of administration, study popula- tions, baseline vitamin D levels, and procedures employed to assess outcomes. Sensitivity analysis eluci- dated the conclusions by highlighting which studies exerted a disproportionate influence on the outcomes and the variations among them. The research indicates that vitamin D supplementation may not consistently outperform control therapies across all parameters. Clinical implications and investigation with current literature Current evidence does not support routine vitamin D screening or supplementation solely for UI/OAB in the general older adult population. Major trials (e.g., VITAL ancillary studies) found no improvement in OAB or UI prevalence/incidence with vitamin D3 2000 IU/day over several years (8, 12). However, vitamin D deficiency is common in certain high-risk groups (e.g., older adults with pelvic floor disorders, pregnant/postpartum women, and children with OAB (4, 13). In these subpopulations, clinicians might consider checking vitamin D levels. Several observational studies and a systematic review and meta-analysis reported associations between low vitamin D and worse lower urinary tract symptoms (LUTS)/UI (5, 14-16). For example, pregnant women in late gestation with vitamin D deficiency had higher UI prevalence and severity (13). In children with OAB, deficiency was far more common than in healthy controls (4). Thus, assess- ing vitamin D status is reasonable in treatment-refractory UI/OAB, particularly if other deficiency risk factors are present (e.g., limited sun exposure, malabsorption, darker skin) (4, 13). A previous systematic review by Bapir et al. (17) also evaluated treatments for urge incontinence in postmenopausal women and identified limited but sug- gestive evidence for vitamin D efficacy in selected cases. For patients with confirmed vitamin D deficiency and symptoms of UI/OAB, supplementation may be consid- ered as an adjunct. Small trials suggest benefits in specific contexts: for example, in premenopausal women with stress UI and vitamin D insufficiency, 8-12 weeks of high- dose vitamin D3 (5,000 IU weekly) significantly reduced leakage scores vs placebo (9). In children with OAB, an 8- week regimen of vitamin D3 2,400 IU/day, combined with standard urotherapy, resulted in greater improvements in voiding frequency, urgency, nocturia, and quality of life compared to urotherapy alone(18). Similarly, postpartum women with UI who received vitamin D replacement showed greater increases in pelvic floor strength (Oxford score) and larger decreases in incontinence questionnaire scores than those doing pelvic-floor exercises alone (1). In sum, when deficiency is documented, supplementation (often at higher-than-routine doses) might improve symp- toms. Nevertheless, vitamin D should not replace guide- line-based UI/OAB care (such as behavioral therapy, pelvic floor training, and pharmacotherapy) but can be an adjunct for patients with deficiency. Adequate dietary cal- cium and monitoring of serum 25(OH)D are advised if high-dose regimens are used. Regarding the dosing of vitamin D, typical large trials used moderate doses (e.g. 2000 IU/day), which did not improve UI/OAB (8, 12). In contrast, trials that reported benefit used higher dosing. One RCT administered 5,000 IU of vitamin D3 once weekly for 3 months to pre- menopausal women (9). The pediatric trial used 2,400 IU daily for 8 weeks (18). These regimens quick- ly raised 25(OH)D levels above 30 ng/mL. Thus, when considering vitamin D therapy for UI/OAB, clinicians might aim for a serum 25(OH)D level in the sufficient range (≥ 30 ng/mL) using adequate dosing; treatment durations in studies have ranged from 8 weeks to 5 years. However, the optimal dose and duration remain uncertain. Careful monitoring is warranted to avoid hypervitaminosis D. Strengths and limitations This review provides a comprehensive synthesis of avail- able RCTs and cohort studies evaluating the impact of vitamin D supplementation on UI and OAB. A key strength lies in the inclusion of diverse populations span- ning multiple age groups, from children to older adults, and various clinical subtypes of UI. Additionally, the employment of sensitivity analyses, including leave-one- out testing, strengthened the robustness of findings and helped identify sources of heterogeneity across studies. This systematic approach enables a more accurate inter- pretation of both between-group and within-group effects of vitamin D supplementation. The findings are limited by significant heterogeneity across included studies in terms of population demo- graphics, vitamin D dosages, treatment durations, base- line vitamin D status, and outcome assessment tools. Many studies had small sample sizes or short follow-up periods, which may reduce statistical power and limit the generalizability of results. The meta-analysis includ- ed both randomized and observational studies, which, while increasing data breadth, introduces potential bias- es such as confounding and selection bias. Moreover, few studies have stratified participants based on baseline vitamin D levels, making it difficult to isolate the effects of repletion in individuals with deficient versus sufficient levels. Archivio Italiano di Urologia e Andrologia 2025; 97(3):14172 S. Thamer Alshahrani, N. Alamri, M. Dhafer Asiri, et al. 8 Recommendations The findings of this review suggest that while vitamin D supplementation does not consistently demonstrate supe- riority over control interventions for UI or OAB. Clinicians should consider assessing vitamin D status in individuals presenting with persistent or treatment-resist- ant UI or OAB, especially among high-risk groups such as postmenopausal women, older adults, postpartum women, and children with OAB. These populations are more likely to exhibit vitamin D insufficiency, which may influence pelvic floor muscle function and bladder detru- sor activity. Vitamin D supplementation may be used as an adjunct to standard UI/OAB management in patients with confirmed deficiency. Although its use should not replace evidence-based first-line treatments such as pelvic floor muscle training, bladder retraining, or pharmaco- logic therapy, supplementation may help enhance thera- peutic outcomes. Higher-dose regimens, such as weekly or daily supplementation for short durations, appear to be more effective in improving urinary symptoms than low-dose maintenance therapy. However, individualiza- tion and monitoring are essential to prevent hypervita- minosis D. For researchers, future clinical trials should adopt standardized definitions of UI and OAB, utilize val- idated outcome measures, and stratify participants according to baseline serum vitamin D levels. Longer fol- low-up durations and adequately powered sample sizes are necessary to evaluate the sustained effects of supple- mentation. Studies should also focus on identifying spe- cific subgroups, such as those with stress incontinence, postpartum incontinence, or pediatric OAB, that may benefit most from vitamin D therapy. CONCLUSIONS The results of this meta-analysis reveal that vitamin D sup- plementation does not produce a statistically significant improvement in UI or OAB symptoms when compared directly with control groups. No meaningful differences were found in the risk of developing UI or OAB, nor in the likelihood of symptom improvement or worsening between intervention and control arms. The included studies exhibited considerable heterogeneity in terms of populations, dosing regimens, and outcome measures, which likely contributed to inconsistent findings across the analyses. Sensitivity analyses helped identify specific studies that disproportionately influenced the overall het- erogeneity. Further high-quality, targeted research is needed to determine which patient subgroups are most likely to benefit and to establish optimal dosing strategies. REFERENCES 1. Aydogmus S, Aydogmus H, Gul S, et al. Is vitamin D replacement effective in the treatment of postpartum urinary incontinence? 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Effect of vitamin D supplementation on urinary incontinence in older women: ancillary findings from a randomized trial. Am J Obstet Gynecol. 2022; 226:535.e1-.e12. 13. Gul S, Aydogmus H, Keles C, et al. The effect of vitamin D defi- DECLARATIONS Ethical approval and consent for participate: The Prospero registration number was given to the protocol of this systematic review [CRD420251107352]. Consent for publication: Not applicable. Availability of data and material: The data supporting this study's findings are available from the corresponding author upon reasonable request. Competing interests: The authors declare no competing interest. Funding: None. Authors' contributions: S.T. Alshahrani: protocol development, manuscript writing, manuscript review. N. Alamri: protocol development, manuscript writing, manuscript review. M.D. Asiri: data collection and manuscript review. M.O. Albabtain: data analysis, manuscript writing. R. Alwadai: data collection and manuscript review. H.M. Assiri: data collection and manuscript review. S. Alghamdi: manuscript review, editing, and senior author. A.T. Alshahrani: data collection and manuscript review., M.J. Bosily: data collection and manuscript review. H. Munyif: data collection and manuscript review. O. Safar: protocol devel- opment, manuscript writing, editing, manuscript review, and sen- ior author. Acknowledgments: Not applicable. Archivio Italiano di Urologia e Andrologia 2025; 97(3):14172 9 Vitamin D in urinary incontinence and overactive bladder ciency on urinary incontinence during third trimester pregnancy. Medicine (Baltimore). 2023; 102:e36044. 14. Yuan P, Wang T, Li H, et al. Systematic Review and Meta- Analysis of the Association between Vitamin D Status and Lower Urinary Tract Symptoms. J Urol. 2021; 205:1584-94. 15. Vaughan CP, Tangpricha V, Motahar-Ford N, et al. Vitamin D and incident urinary incontinence in older adults. Eur J Clin Nutr. 2016; 70:987-9. 16. Zhang W, Zheng X, Wang Y, Xiao H. Vitamin D Deficiency as a Potential Marker of Benign Prostatic Hyperplasia. Urology. 2016; 97:212-8. 17. Bapir R, Bhatti KH, Eliwa A, et al. Treatment of urge inconti- nence in postmenopausal women: A systematic review. Arch Ital Urol Androl. 2023; 95:11718. 18. Chen H, Zhang Z, Wu S, et al. Efficacy and Safety of High-Dose Vitamin D Supplementation vs Solifenacin or Standard Urotherapy for Overactive Bladder Dry in Children: A Randomized Clinical Trial. J Urol. 2024; 211:26-36. Correspondence Omar Safar (Corresponding Author) omar2725@hotmail.com Urology Department, Armed Forces Hospital Southern Region, Khamis Mushayt, Saudi Arabia Saad Thamer Alshahrani saadkkumed@gmail.com Hassan M. Assiri dr.assiri2020@gmail.com Saleh Alghamdi alobead@hotmail.com Urology Department, Armed Forces Hospital Southern Region, Khamis Mushayt, Saudi Arabia Naif Alamri drnaifalamri@hotmail.com Urology Department, Saudi German Hospital, Asir, Saudi Arabia Mohammad Dhafer Asiri asirimohd2030@gmail.com Urology Department, Health Cluster 1, Riyadh, Saudi Arabia Meshal Omar Albabtain meshal_al_babtain@hotmail.com Urology Department, King Saud Medical City, Riyadh, Saudi Arabia Raed Alwadai ri_mw@hotmail.com Urology Department, King Abdullah Hospital, Bisha, Asir, Saudi Arabia Ali Thamer Alshahrani alithamer798@gmail.com College of Medicine, King Khalid University, Abha, Saudi Arabia Mohanad Jebril Bosily dr.bosily@gmail.com Ministry of Health, Aseer Health Cluster, Asir, Saudi Arabia Hussain Munyif hussainmunief@gmail.com Urology Department, King Khalid Hospital, Najran City, Saudi Arabia