Glutamate is a naturally occuring neurotransmitter. It is also naturally occuring in foods, like bone broth and green peas. And it is a really common additive to foods, hiding under lots of names. Glutamate is converted to GABA, another neurotransmitter. If your GABA is too low, or your glutamate too high, you get an imbalance.
Glutamate opens up calcium ion channels, which are responsible for turning on lots of processes in the body. Magnesium and taurine help close those channels.
Reasons to Suspect
Autism, MSG sensitivity, unexplained congestion, high keratin, sulfur cravings, high calcium symptoms.
Glutamate can increase in response to high levels of ammonia, due to an inability to convert it to GABA, or for other reasons I haven't read about yet. A glutamate/GABA imbalance can be exacerbated by glutamates in the diet.