I am someone who has a negative reaction to it. It's possible that if I ate seaweed in the volumes that equalled the concentrations of disembodied MSG, I would have the same reaction.
I have a negative reaction to a few foods, actually, and some wines, and most indoor pets. I'm not saying that it's the same mechanism in effect -- just noting that bodies do have genuine reality-based reactions to entirely "natural" foods.
That said, I wish I'd known that @chromedome tip in my 30s, a time when I invested a whole lot of stress in getting elderly ailing people to eat enough to survive their medicine. My technique was LARGE PINCHES of sugar.