Associations Between Vitamin K and Suicide Attempts in Patients with Depression: A Case-Control Study.

Background: Hypovitaminosis K has been linked to depression and suicide, but epidemiological research is scarce. This study aimed to explore the association among vitamin K with depression and suicidal attempts. Methods: This was a retrospective cross-sectional study involving 146 cases with a history of suicidal attempts and 149 subjects without a lifetime history of suicidal attempts. The levels of thyroid hormones, lipid profile, inflammatory cytokines, and vitamins were measured. Results: Subjects who had suicidal attempts presented with a significant decrease in FT4, TC, vitamin D, and vitamin K but increased CRP levels. In these variables, vitamin K has a better diagnostic value for suicidal attempts in depressed patients, with a sensitivity of 0.842 and a specificity of 0.715. Correlation analysis suggested that vitamin K was significantly and positively related to FT4, TC, LDL, and sdLDL. Multivariate analysis showed that serum vitamin K level predicts suicidal attempts in depressive patients (OR = 0.614, Conclusion: Our study suggests that low vitamin K levels were correlated with suicidal attempts in patients with depression, indicating that vitamin K deficiency might be a biological risk factor for depression.