The Association of Vitamin D Deficiency with Depressive Disorders in Patients with Eating Disorders: A Cross-Sectional Study

Background Vitamin D deficiency and depressive disorders are both common in patients with eating disorders (EDs). However, the association between vitamin D status and current depressive disorder (CDD) in ED populations remains insufficiently explored. Methods We conducted a cross-sectional study including 481 outpatients with EDs assessed at a specialized ED unit in Montpellier, France. Psychiatric diagnoses were established using the Mini-International Neuropsychiatric Interview (M.I.N.I.). ED severity was assessed with the Eating Disorder Examination Questionnaire (EDE-Q). Serum 25-hydroxyvitamin D levels were measured as part of routine clinical assessment, and vitamin D deficiency was defined as < 20 ng/mL. Odds ratios (ORs) were estimated using logistic regression. Results Vitamin D deficiency was significantly associated with higher odds of CDD (OR 1.98, 95% CI 1.20–3.28; p = 0.008). This association persisted after adjustment for ED severity, psychiatric comorbidities, and season of assessment. No significant interactions were found between vitamin D deficiency and ED subtype, EDE-Q score, or season. Conclusions Vitamin D deficiency was associated with the presence of a current depressive disorder in patients with eating disorders, independently of ED subtype, severity, and seasonality. These findings support the clinical relevance of assessing vitamin D status in patients with EDs presenting with depressive symptoms. Longitudinal studies are needed to clarify the direction and clinical implications of this association.