MSG is a clear common denominator. Many people report that if they avoid anything with MSG (under any of its names), they avoid the associated problems. That doesn't mean it's MSG.

Why do studies focus on the MSG? Because they are sparked by the motivation to clear MSG's name (which could actually be right). They don't care about finding the root cause of these symptoms.

The proper scientific approach is to ignore the MSG hypothesis of the self-reported sufferers and get to the root cause, not simply to test that hypothesis and be done.

> "Middlebrow dismissals" of their condition don't really help them either.

Exactly; same in this MSG situation.