FWIW, I use to be "extremely" hypersensitive to MSG/free glutamic acid.
However, after lowering my pathogen burden to a fraction of what it was and I'm guessing mycoplasma being a large part, I can now consume very large quantities of Mono-Sodium-Glutamat (Natrium Glutamat) with little reaction.
In short, MSG/free glutamic acid that's found in all these processed foods are very bad but if one is hypersensitive may want to look into the pathogen issue being responsible and possible mold/mycotoxins as well.