I think it’s very likely that something with MSG on the label often includes things like anti-caking agents or nitrates that may actually be the culprit. I kept a food diary for a year and the common headache trigger seemed to be “MSG”. Changing my diet to avoid it eliminated the headaches. So it really doesn’t matter to me if someone on the internet says it can’t be MSG. The practical result in my case was close enough. I have sympathy for anyone that suffers from migraines.