Todd,

Some are luckier than others.  I'll agree that a single crouton might not
be too big a problem, but eat a hotdog (especially one listing gluten as an
ingredient) and I'm not going to get a good night's sleep.  I haven't
noticed a reaction specifically to MSG either, but I can tell you that
processed foods in general now cause me stomach problems (like on that
Pepto Bismol commercial).  They always did, but it's even worse now.

John Pavao

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I have to say that in my own case my body doesn't seem to detect
contaminants in any way that I can discern by introspection.
Mind you, I think it is best to avoid these things, and I make
every attempt to do so.  But if and when I slip up and eat some
MSG or other rubbish, I don't experience anything  unusual.