Associations of dietary biotin intake on anxiety and depression: findings from a population-based prospective cohort study.

Background: Some cross-sectional have found the negative association between dietary biotin intake and anxiety and depression symptoms. However, there is still a lack of cohort study in this field. So we conduct this prospective cohort study to investigate the association between dietary biotin intake and anxiety and depression, evaluate their dose-response relationship and the mediating role of inflammation in this process. Methods: A total of 144,439 UK Biobank participants without baseline anxiety or depression were included. Dietary biotin intake was derived from the 24-h Oxford WebQ data, and anxiety and depression were defined in accordance with the ICD-10 criteria. Cox proportional hazards models and restricted cubic splines (RCS) were used to evaluate longitudinal associations. The Karlson-Holm-Breen method was used to examine the mediating effect of inflammation. Results: A total of 144,439 participants were included in this study with a median follow-up of 14.06 years. Compared to Q1 group, dietary biotin intake was associated with a reduced risk of anxiety or depression (HR: 0.86 [0.82, 0.91] for Q2; HR: 0.84 [0.79, 0.88] for Q3; HR: 0.86 [0.81, 0.91] for Q4). Similar results were also found in anxiety, depression, and their comorbidity. RCS existed an approximately "L-shaped" dose-response relationship between biotin and both anxiety and depression. Except for depression and comorbidity, both single mediating indicators and composite mediating indicators played a partial mediating role in the course of this. Conclusion: Dietary biotin intake exhibited an approximately L-shaped nonlinear relationship with anxiety and depression risk, where risk decreased with increasing intake up to a moderate threshold, beyond which no further reduction was observed. This association may be partially mediated by inflammation.