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.

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).

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

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