One reason why MSG can give such a bad punch is that often it goes hand in hand with high sodium. If your meal has 3K of sodium AND any form of MSG, yes, it can really do a trigger on the head. (Now before anyone says "but I don't eat that much sodium!"....if you eat a 2 person meal that is commercial, yes, you can. Sad it is.)

MSG is well hidden of course in many foods, both in naturally occurring forms (mushrooms for example) and in crafty labels for it as mentioned.

One reason to make your own meals of course. MSG though is something to consider of this vein "Use in moderation". In other words....small amounts don't affect most people, but chowing down a feast of it will. So avoid eating the 4 serving meal high in it in one serving It is like my brother and his migraine triggers - he can drink one orange soda but not 6 of 'em. Same with me - 1 red cookie won't do it, but a whole package...and yeah, not good.