Magnesium helps build bones, make proteins, release energy stored in muscles and regulate body temperature.
In the cover story of the Dec. 2 issue of Neuron, MIT researchers report a possible new role for magnesium: helping maintain memory function in middle age and beyond.
The adult daily nutritional requirement for magnesium, a trace mineral found in foods such as dark green, leafy vegetables, is around 400 mg a day.
But studies show that as many as half of all Americans do not consume enough magnesium.
Magnesium deficits have been tied to allergies, asthma, attention deficit disorder, anxiety, heart disease, muscle cramps and other conditions.
Associate Professor Guosong Liu and postdoctoral associate Inna Slutsky at MIT's Picower Center for Learning and Memory found that magnesium helps regulate a key brain receptor important for learning and memory.
Their work provides evidence that a magnesium deficit may lead to decreased memory and learning ability, while an abundance of magnesium may improve cognitive function.
"Our study shows...maintaining proper magnesium in the cerebrospinal fluid is essential for maintaining the plasticity of synapses," the authors wrote.
Loss of plasticity in the hippocampus, where short-term memories are stored, causes the forgetfulness common in older people.
Synapses, like speakers, have a level of background noise that can get in the way of transmitting their signal from one neuron to another.
Just as our ears become more sensitive to nuances in music played on a top-of-the-line music system, synapses become more plastic when background noise is reduced.
Magnesium is the gatekeeper for the NMDA receptor, which receives signals from an important excitatory neurotransmitter involved in synaptic plasticity.