Becky sometimes has terrible migraines and so tries to avoid foods containing MSG. The full form of MSG is mono sodium glutamate. Glutamate is an extremely important neurotransmitter present in the brain. It performs the role of increasing the excitability of the neurons. Consumption of food rich in MSG leads to an increase in the levels of glutamate in the blood. Glutamate causes shrinking of the blood vessels and heightens the pain perception. This leads to a migraine attack.