Scientists have been doing challenge studies with MSG for 4 decades, and no study that presented subjects with MSGs and detected any adverse reactions significantly different than placebo has ever reproduced.
Even the (rebutted, non-reproducing) studies that showed adverse reactions to MSG (in the 80s and early 90s) showed headache as one of the symptoms not associated with MSG (tingling and numbness were more closely associated).
I don't doubt you're able to give yourself a migraine, but I do doubt that you're controlling for MSG.
This might be one of the best-studied food safety questions in the literature.
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.
You can't do a double-blind expepriment on yourself, but you can simulate one.
Double refers to the fact that not only do the test subject not know what treatment they are getting (e.g. real or placebo), but also the staff who administer that treatment do not know: both are blind, hence double. This is important because if the administrators know, then something in their behavior such as body language could leak the information to the test subjects.
If administrator and test subject are the same person, it cannot be double. However, you can take steps to prevent yourself from knowing what you're taking, like preparing identical containers which are randomized and whatnot. If there is no second human there serving to you who could leak clues then it may be as good as double blind.
Prepare your two samples. Put them in identical containers. Attach sealed envelopes that record which one is which. Mix them up in such a way that you can't tell them apart anymore. Randomly mark one A and one B. Perform your experiment on A and B. Once you have the results, open the envelopes to find out which one was which.
Even the (rebutted, non-reproducing) studies that showed adverse reactions to MSG (in the 80s and early 90s) showed headache as one of the symptoms not associated with MSG (tingling and numbness were more closely associated).
I don't doubt you're able to give yourself a migraine, but I do doubt that you're controlling for MSG.
This might be one of the best-studied food safety questions in the literature.