Studies indicate that in the presence of a stressor or anxiety, healthy individuals’ levels of magnesium (Mg ++) become depleted even though they have had normal levels before. Thus, it comes as no surprise that some people may wonder if they should take magnesium supplement for anxiety.
Mg ++ is an essential cation for the human body that participates in many important functions within the body and the central nervous system, ranging from protecting biological membranes, DNA replication to neurotransmitter synthesis (i.e., neurochemical messengers in the brain) and blocking NMDA receptors. NMDA receptors play an important role in the activation of the Hypothalamic-pituitary-adrenal axis -HPA axis (i.e., a circuit of brain structures in the central nervous system whose activity influences the release of stress hormones from the endocrine system), the activation of which is associated with anxiety.
Notably, chronic anxiety is associated with an abnormal increase in the sensitivity of the excitatory stress response (i.e., hyperventilation, increased heart rate, etc…), which involves the NMDA receptor activity. Magnesium by contrast inhibits the activity of those receptors and by extension influences the degree of activation of the HPA axis. Levels of magnesium are tightly regulated and fairly resistant to dietary depletion; however this regulation seems to be associated with levels of adrenaline, since an increase in adrenaline causes an increase in magnesium urinary excretion. Hence, there is an association between low levels of available magnesium and anxiety/stress.
Admittedly, the present study investigates whether or not taking a magnesium supplement when feeling anxious before a test could help lower the anxiety. Unfortunately, the results do not support this hypothesis as the investigators did not find significant changes in anxiety following the intake of a magnesium supplement for five days before the participants took their finals.
Reference:
Gendle, M.H., & O’Hara, K.P. (2014). Magnesium supplementation and test anxiety Oral Magnesium Supplementation and Test Anxiety in University Undergraduates.