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

Abstract

Adequate zinc and magnesium intakes may be beneficial for the prevention and treatment of mental health problems, such as depression, anxiety and attention-deficit hyperactivity disorder. Zinc is a co-factor of many enzymes that play a role in brain function (1) and zinc modulates neuronal excitability by inhibiting both the gamma-aminobutyric acid (GABA) and N-methyl-D-aspartate (NMDA) receptors (2) . Magnesium is another potent antagonist of the NMDA receptor complex (3) and magnesium deficiency has been related to symptoms such as agitation, anxiety, irritability and hyperexcitability (4) . We aimed to investigate the prospective associations of dietary intakes of zinc and magnesium with internalising and externalising behaviour problems in adolescents participating in both the 14 and 17 year follow-ups of the Western Australian Pregnancy Cohort (Raine) Study (n 684).Dietary intakes of zinc and magnesium were assessed using a validated food frequency questionnaire and mental health symptoms were assessed using the Youth Self-Report (YSR). General linear mixed models were used to investigate the prospective relationships between zinc and magnesium intakes and YSR T-scores, adjusting for sex, physical activity, family income, supplement status, dietary misreporting, BMI, family functioning and energy intake.After adjusting for potential confounders, higher dietary intake of magnesium (per standard deviation) was significantly associated with reduced externalising behaviours and there was a trend towards reduced externalising behaviours with higher zinc intake.This study shows an inverse association between dietary magnesium intake and externalising behaviour problems in adolescents. We observed a similar trend, although not statistically significant, for zinc intake. Promoting increased consumption of mineral-rich foods, such as leafy/cruciferous vegetables, nuts and legumes, along with supplementation to address identified micronutrient deficiencies, may be a useful strategy to prevent mental health and behavioural problems in adolescents. In order to determine any benefit of magnesium and/or zinc supplementation in the prevention and treatment of externalising behaviour problems, randomised controlled trials using optimal doses are necessary.