Was MSG or MonoSodium Glutamate ever proven conclusively to have adverse health effects?

Do you ever use it in cooking?

I use MSG fairly regularly, myself. Garlic cheese bread is butter with garlic, cheese, salt, white pepper and MSG smeared on crusty bread and baked loosely covered in foil. (My late aunt’s recipe.)
There are other things I use it in/on, but I try to be extra judicious – putting some in my palm and then spreading it with a pinch of my fingers from the other hand. I know exactly how much I use, and where it goes.

Am I being overly cautious? Is it okay to shake it on like salt? I love the flavor and after I pinch it on food, I get to eat what’s left on my palm!