That's rather curious to read, when you're from a chunk of Latin America where MSG was never seen as a big deal - it's that stuff that you'd sprinkle over rice croquettes, or use in some Asian dishes, and... that it? The only times where I've found people claiming headaches were on the internet. (Usually known by the name of a Japanese brand.)

I tend to avoid it though - at least pure MSG is boring. Soy sauce, beef broth, tomato paste, Parmesan, those are usually better - because they'll give you that savouriness plus other flavours. And it's outright pointless to sprinkle it over meats, it's like dropping a bucket of water in the ocean.