Oh my gawd!!!It is Monosodium glutamate used to season food, mostly processed and packaged food. This link at the bottom shows all the different names that MSG can show up as on your food list.
Your body can't deal with it in healthy ways and it has bad effects on many people - probably a factor in why so many obese folks are actually malnourished. Below are pics of mice fed the same amount of calories, but one was fed MSG while one was not.