I have seen something similar on TV to do with MSG. The room was split down the middle and I believe the participants were told half the room ate food with MSG

I have seen something similar on TV to do with MSG. The room was split down the middle and I believe the participants were told half the room ate food with MSG and the other half without. They interviewed the participants after and the majority on the side with MSG had symptoms. The only problem was that no one had consumed MSG. going off of memory from something I saw a decade ago