Society of Diabetic Nephropathy Prevention Journal of Preventive Epidemiology 2476-3934 11 1 2026 01 01 Investigating the relationship between vitamin B intake and endometriosis: a systematic review and meta-analysis e39282 e39282 10.34172/jpe.2025.39282 EN Amirhosein Moradi https://orcid.org/0000-0001-8706-8371 Ahmadreza Siyasari https://orcid.org/0000-0002-6004-5652 Sara Abutalebi Nasrabad https://orcid.org/0009-0006-1445-761X Tahmineh Ezazi Bojnordi https://orcid.org/0000-0001-6874-9817 Saba Bazzazi https://orcid.org/0009-0006-2528-0450 Sadaf Rassouli https://orcid.org/0009-0002-8264-7766 Peyman Khajehnabi https://orcid.org/0009-0005-6377-5342 Maryam Farajisani https://orcid.org/0009-0005-6866-9282 Mehrangiz Ghafari https://orcid.org/0000-0003-2942-4651 Journal Article 10.34172/jpe.2025.39282 2025 08 06 2025 10 06 Introduction: Vitamin B promotes the inactive metabolism of estrogen and inhibits endometrial growth. Accordingly, the present study aimed to examine the relationship between vitamin B intake and endometriosis. Materials and Methods: Databases Scopus, PubMed, ProQuest, Web of Science, Cochrane, Embase, and Google Scholar Search Engine were used for articles published until July 18, 2025. Data was entered into SPSS 19 and analyzed using STATA 14. Results: Generally, administration of vitamins B2 (OR: 0.76, 95% CI: 0.64, 0.90) and B3 (OR: 0.98, 95% CI: 0.96, 1) reduced the risk of endometriosis. However, the relationship between vitamins B1 (OR: 1.04, 95% CI: 0.92, 1.17), B6 (OR: 0.98, 95% CI: 0.89, 1.08), B9 (OR: 1.01, 95% CI: 0.84, 1.21), and B12 (OR: 1.06, 95% CI: 0.98, 1.14) and endometriosis was statistically insignificant. According to the subgroup analysis, vitamin B1 intake in cohort studies increased the risk of endometriosis. Vitamin B2 administration in case-control studies and in the fourth quartile reduced the risk of endometriosis. Vitamin B9 intake, on the other hand, increased the risk of endometriosis in cohort studies and the fourth quartile. Conclusion: Vitamin B2 and B3 intake reduced the risk of endometriosis in women by up to 24% and 2%, respectively. However, to ensure the validity of the results, further studies on this subject are required. Registration: This study has been compiled based on the PRISMA checklist, and its protocol was registered on the PROSPERO (ID: CRD420251112519) and Research Registry (UIN: reviewregistry2028) websites.