Magnesium plays a critical role in brain health by preserving neuronal function during periods of downtime. Deficiency can result in abnormal neuronal excitation (cells have more activation during periods when they are not intentionally activated), anxiety, and stress.
Magnesium has been shown to increase NMDA transmission and signaling, a pathway in the brain that controls synaptic plasticity and memory function [1, 2, 3, 4].
A study in aged rats showed that 50 mg/kg/day elemental magnesium was associated with increased spatial memory (short and long term), memory recall, and working memory (short term only) . Another arm of the same study using young rats showed that enhanced learning effects ceased upon cessation of magnesium administration .
In a recent double-blind, placebo-controlled human trial using magnesium threonate, researchers concluded that, "Overall cognition improved significantly at week 6 and maintained improvement at week 12". They also concluded that magnesium improved 'brain age' by 9 years based on "restored impaired executive function of the subjects" (age 50-70) .
Additionally, neuroscientists from universities in Beijing, Texas, and Toronto found that increased serum magnesium in the brain enhanced synaptic plasticity, and improved learning and memory .
Twelve scientists at MIT conducted a study on magnesium L-threonate and concluded that “an increase in brain magnesium enhances both short-term synaptic facilitation and long-term potentiation and improves learning and memory functions” .
Lastly, increased brain magnesium levels may prevent or reverse cognitive deficits and synaptic loss .
Effects On Stress and Mood
Magnesium has been shown to improve mood during stressful conditions [8, 9, 10, 11].
While there isn’t a good relationship between serum magnesium and depression, magnesium deficiency is associated with major depression in otherwise healthy individuals .
One study showed that the removal of magnesium from the diet of rats resulted in anxiety and depressive-like symptoms .
A review from 2010 concluded that increased rates of depression were correlated with dietary reduction of magnesium, and reported an inverse relationship between magnesium intake and depressive symptoms when controlling for both socioeconomic and lifestyle factors [14, 15].
Effects On Hyperactivity
There is some evidence suggesting that magnesium deficiency is related to hyperactivity. One study of 116 hyperactive children noted a magnesium deficiency of 95% (16).
In another intervention of 50 hyperactive children there was a significant improvement in hyperactivity in response to 200 mg magnesium per day over a 6 month period .
Effects On Sleep
Magnesium supplementation confers sedative-like effects that can improve sleep quality.
When a study sample of 12 healthy elderly subjects took an increasing dose of magnesium (from 346 to 738 mg), slow wave sleep quality was significantly increased .
Effects On Testosterone
Magnesium may have the potential to either increase or normalize testosterone levels, though the magnitude of effect is likely pretty small, existing in the range of several percentage points [19, 20].
Possibility of gastrointestinal upset in high doses or when taken on an upset stomach.