Here's another tidbit for consideration. MSG is the salt form of Glutamic Acid, which is a nonessential amino acid. In this case "nonessential" means that we don't need to eat it because our bodies can make it by itself. it is essential to the production of every part of our body. That's why it tastes good: a good flavor is how our tongue tells our brain that "yes, we should eat this" (some exceptions apply).

So eating MSG is eating something that naturally occurs in your body anyways, which makes it very hard to pose a case that it's harmful.