Before our food journey, sometimes both of us would get horrible migraines at the same time soon after eating out. We thought it must be too much MSG and would avoid the place thereafter. We learned a bit more about ourselves and about MSG when we started a food chemical elimination diet.
The main thing being while MSG (monosodium glutamate) is the artificial form, there are plenty of natural sources of free glutamate, which act identically in the body. This might be why sensitivity to MSG by itself has not been proven.
At the end of the elimination diet we did a free glutamate challenge, actually a soy sauce challenge in our case. We each had a tablespoon with our meal. Mate had a headache for a couple of days. I was expecting migraine as well but instead I felt my whole body was abuzz, pulsing as if I’m running. I didn’t get a wink of sleep that night, wasn’t even tired. Next day still going and barely two hours of sleep, the third day still less than four hours of sleep, finally by the fourth day I came back to somewhat normal. I slept just six hours in three days with no bowel movement either. Suspiciously like hypomania.
I thought about why I didn’t get migraine as I expected. Most of my migraine episodes happen after exercise or watching a movie. And with the elimination diet they mostly disappeared. So it seems the combination of allergen and overstimulation (by exercise etc.) was the main cause for me. So without any allergen I only felt the overly stimulated body and brain. Free glutamate as excitotoxin explains the parallels to exercise induced allergy symptoms.