Non-obese women with PCOS show no significant differences in serum vitamin D levelsVitamin D Levels Show No Difference in Non-Obese PCOS Patients

IntroductionVitamin D deficiency is linked to increased risk of polycystic ovary syndrome (PCOS) and may worsen metabolic disorders such as insulin resistance. However, evidence remains inconsistent regarding vitamin D status in non−obese women with PCOS. This study aimed to perform the first systematic review and meta−analysis evaluating serum vitamin D levels in non−obese PCOS patients.MethodsRelevant studies were searched in PubMed, Embase, Cochrane Library, and Web of Science up to May 2025. Eligible studies comparing non−obese PCOS women and healthy controls were included. Two reviewers independently screened articles. Meta−analysis was conducted using a random−effects model, supplemented by subgroup, sensitivity, and publication bias analyses.ResultsEleven studies involving 533 non−obese PCOS patients and 574 controls were included. No significant differences were found in serum 25(OH)D or 1,25(OH)2D levels between groups. Heterogeneity was mainly attributed to region, diagnostic criteria, BMI, and assay methods. Significant publication bias was detected.DiscussionSerum vitamin D levels are not significantly associated with non−obese PCOS, implying vitamin D deficiency may be driven by obesity rather than PCOS pathogenesis. Vitamin D supplementation may benefit obese PCOS patients, and further prospective studies are needed.Systematic review registrationhttp://www.crd.york.ac.uk/PROSPERO, identifier CRD420251168257.