I personally use some spice blends and rubs that have msg. Some of these are from brethren on this site, some are not. I love these blends/rubs and will continue to use them, however I notice after consuming larger amounts I often end up with headaches. I have tried changing things from my cooks and have not found any change. This may or may not have to do with msg.
I do know, I do not know enough about it nor have enough factual information regarding the matter to properly determine msg as the cause. At this point my headaches are purely coincidental. Until I am able to actually determine this is all because of MSG I will continue to experiment and eliminate things from my cooks until I'm able to be comfortable.
With that being said I am a bit suspicious.
UDS, MUDS, Weber 22 OTG