Society of Diabetic Nephropathy Prevention Journal of Nephropharmacology 2345-4202 13 2 2024 06 29 Association between vitamin D and bladder neoplasm; a systematic review and meta-analysis e11668 e11668 10.34172/npj.2024.11668 EN Anna Ghorbani Doshantapeh https://orcid.org/0009-0007-1604-9342 Mohammad Hamidi Madani https://orcid.org/0000-0002-4601-4745 Ali Khodaparast https://orcid.org/0009-0008-2380-8893 Rasoul Jafari Arismani https://orcid.org/0000-0001-7440-0507 Ardeshir Matoofi https://orcid.org/0009-0006-0889-8355 Delnia Heidari https://orcid.org/0009-0007-5305-5872 Golmis Abdolmohammadi https://orcid.org/0000-0001-9231-408X Farshad Gharebakhshi https://orcid.org/0000-0001-5495-609X Jahanbakhsh Vahdatnejad https://orcid.org/0000-0002-2587-288X Journal Article 10.34172/npj.2024.11668 2023 10 14 2024 01 12 Introduction: Bladder neoplasm ranks as the second most prevalent reproductive system malignancy worldwide. On the other hand, the vitamin D as an anti-cancer agent has been a subject of long-standing speculation. Hence, the objective of this study is to explore the correlation between vitamin D and bladder neoplasm risk. Materials and Methods: This systematic review and meta-analysis were designed following the PRISMA checklist. Eligible studies were identified through searches on ProQuest, PubMed, Web of Science, Google Scholar, and Cochrane, with no time restrictions until November 18, 2023. Data analysis was conducted utilizing the STATA 14 software. Results: Serum vitamin D levels less than 50 nmol/L increased the risk of bladder neoplasm (OR: 1.33; 95% CI: 1.08, 1.64), muscle-invasive bladder cancer (MIBC) (OR: 2.73; 95% CI: 1.80, 4.14) and non-muscle invasive bladder cancer (NMIBC) (OR: 1.87 (95% CI: 1.39, 2.52)). However, the risk of bladder neoplasm in people whose serum vitamin D level was less than 50 nmol/L did not increase with age. Vitamin D serum levels greater than or equal to 50 nmol/L in people aged 40 to 49 (OR: 0.51; 95% CI: 0.27, 0.99) prevented bladder neoplasm, but no significant association was seen in people over 50 years old. In addition, there was no significant association between daily vitamin D intake and the risk of bladder neoplasm (OR: 1.13; 95% CI: 0.63, 2.06). Conclusion: The serum vitamin D less than 50 nmol/L was correlated with bladder cancer risk increasing, including MIBC and NMIBC. Registration: This study has been compiled based on the PRISMA checklist, and its protocol was registered on the PROSPERO (CRD42023487519) and Research Registry (UIN: reviewregistry1754) Websites.