The difference is that those foods are high in glutamate, not the chemically-stabilised for easy human sprinkling 'monosodium glutamate'.

I've long suspected any headaches or perceived ill-effects from MSG consumption are probably just sodium spikes from dishes made with a bit too much msg and salt, perhaps washed down with some not enirely quenching alcoholic beverage.

Tyramine is supposed to trigger migraines and they are in parm and aged beef.

There is a big difference between the glutamic acid in tomatoes and the refined devilry that is put in Campbell's soup, KFC chicken, and cheap asian food. I do have to watch protein powders and bars that have glutemic acid ... some of these will give me a headache (I am looking at you muscle milk).

Eat a teaspoon of MSG. Remember, "its guaranteed not to be the MSG."