Is MSG Really in Vietnamese Food?

In 1968, Dr. Robert Homan Guo wrote to the New England Journal of Medicine asking for help in identifying source of phenomenon that he labeled Chinese restaurant syndrome. The story behind this was supposed to have been a prank by a white guy named Dr. Steele who made it up as a joke. It turns out this letter is actually real, but there was basically a story that went around that it was this guy named Dr., Homengua,. And so for a bit everyone was like, "Oh my god, this whole thing was started by a prank," and then they realized how true it was. So we just like... I think it's also really in Vietnamese food, uses