Low dietary intake of magnesium is associated with increased externalising behaviours in adolescents

Objective: Adequate Zn and Mg intakes may be beneficial for the prevention and treatment of mental health problems, such as depression, anxiety and attention-deficit hyperactivity disorder. We aimed to investigate the prospective association between dietary intakes of Zn and Mg and internalising and externalising behaviour problems in a population-based cohort of adolescents. Design: Prospective analysis (general linear mixed models) of dietary intakes of Zn and Mg assessed using a validated FFQ and mental health symptoms assessed using the Youth Self-Report (YSR), adjusting for sex, physical activity, family income, supplement status, dietary misreporting, BMI, family functioning and energy intake. Setting: Western Australian Pregnancy Cohort (Raine) Study. Subjects: Adolescents (n 684) at the 14-and 17-year follow-ups. Results: Higher dietary intake of Mg (per SD increase) was significantly associated with reduced externalising behaviours (beta = -1.45; 95% CI -2.40, -0.50; P = 0.003). There was a trend towards reduced externalising behaviours with higher Zn intake (per SD increase; beta = -0.73; 95 % CI -1.57, 0.10; P = 0.085). Conclusions: The study shows an association between higher dietary Mg intake and reduced externalising behaviour problems in adolescents. We observed a similar trend, although not statistically significant, for Zn intake. Randomised controlled trials are necessary to determine any benefit of micronutrient supplementation in the prevention and treatment of mental health problems in adolescents.