"Glutamic acid (glutamate) is an amino acid used by the body to build proteins. Under normal circumstances, humans are able to meet bodily glutamate requirements either from the diet or by making it from precursor molecules. Glutamate is the most common excitatory (stimulating) neurotransmitter in the central nervous system. Although glutamine and glutamic acid have similar names, they are structurally different.
The fluid produced by the prostate gland contains significant amounts of glutamic acid, and this amino acid may play a role in normal function of the prostate. In one study, symptoms of benign prostatic hyperplasia (BPH) were improved in a group of 45 men taking 780 mg of glutamic acid per day for two weeks and then 390 mg for the next two and a half months in combination with equal amounts of the amino acids, alanine and glycine, an effect also reported by other researchers."
I pasted this information from orthomolecular.org. They did not say who wrote it. There is an orthomolecular theory that glutamate is bad for schizophrenia. According to this theory glutamate should be avoided in the diet. My own theory is that it may also be bad for bipolar disorder. If this is true, a diet very low in protein might benefit bipolar disorder. Such a diet has never been tried in bipolar disorder.