Association Between Riboflavin Intake and Suicidal Ideation: A Nationwide Study in Korea

Background/Objectives: In recent years, there has been an increased interest in reducing suicide rates through dietary modification; however, the relationship between riboflavin intake and suicide risk remains unclear. This study aims to examine the association between dietary riboflavin and suicidal ideation. Methods: A total of 17,320 participants from the Korean National Health and Nutrition Examination Survey (KNHANES) 2014–2020 were included. Suicidal ideation was assessed using the ninth item of the Patient Health Questionnaire-9 (PHQ-9). Riboflavin intake was evaluated through dietary assessments. Multivariate logistic regression, restricted cubic spline (RCS) regression analysis, subgroup analysis, and interaction tests were conducted to explore the relationship between riboflavin intake and suicidal ideation. Results: There was a statistically significant association between riboflavin intake and suicidal ideation [OR (95%CI): 0.83 (0.77, 0.91), p < 0.001], after full adjustment for covariates. The linear trend test, using Q1 as the reference, showed ORs (95% CI) for Q2 and Q3 of 0.96 (0.81, 1.15) and 1.06 (0.80, 1.42), respectively. The RCS analysis revealed a non-linear pattern in the relationship between riboflavin intake and suicidal thoughts. This association was particularly significant among women and individuals younger than 60 years. Subgroup analyses and interaction tests indicated that the associations remained consistent across subgroups and were not influenced by factors other than anaerobic exercise. Conclusions: Our findings suggest a non-linear inverse relationship between riboflavin intake and suicidal ideation, with notable variations by sex and age. Modifying dietary riboflavin intake may be a crucial strategy for reducing suicide risk.