Objective: The current prevalence of mental health problems in Western populations is approximately 20% and half of all adult mental health disorders are estimated to originate in adolescence. Diet plays an important role in modulating psychological wellbeing and B-vitamins are vital for the synthesis of neurotransmitters such as serotonin. We aimed to examine the relationship between B-group vitamins and adolescent mental health and behaviour.Methods: This is a cross-sectional analysis of the West Australian Pregnancy Cohort (Raine) Study. The 17-year follow-up included collection of a food frequency questionnaire allowing B-vitamin intake calculation. Mental health was assessed using the Youth Self Report (YSR) which measures total, internalising (withdrawn/depressed) and externalising (aggressive/delinquent) behaviour scores. Multiple linear regression was used to analyse associations between B-vitamins and mental health with adjustment for relevant confounders (n = 709).Results: Lower intake of vitamins B1, B2, B3, B5, B6, and folate was associated with higher externalising behaviour scores (p ≤ 0.05). Reduced intake of vitamin B6 and folate was associated with higher internalising behaviour scores (p ≤ 0.05).ConclusionsPoor nutrition may contribute to the pathogenesis of mental health problems in adolescence. The role of B-vitamins requires further investigation in randomised controlled trials.Copyright © 2012 Elsevier Inc. All rights reserved.