Thanks to all who have posted comments to my original question.
I wrote Dr. Blaylock (author of Excitotoxins: The Taste That Kills) with this question and he wrote back to say he had never heard that supplementing with Iodine would exacerbate MSG-reactivity. So I have started on 3 drops of Lugol's in a bit of water with my dinner and we'll see what happens. If I don't try, I will never know.
I also wrote to Dr. Flechas and asked him the same question but have not yet had a response. If he responds, I will post it.
Regarding the dosage of Iodine one should take - is it best to start slowly and slowly increase the dose up to the recommended 50 mg.?