MSG naturally occurs in basically everything savory or meaty, so any side effects caused by artificial MSG would probably arise from consumption of natural foodstuffs too. In general we produce lots of glutamate ourselves too (it's one crucial aminoacid), so I honestly find it unlikely that dietary sources can have an influence on how much of it ends up in the brain, but given that there's no definitive science to back this it's all up for debate.

MSG does not cross the blood brain barrier in significant amounts.

I get sinus headaches from all things glutamate. MSG in chips, parmesan, tomatos, etc. Doubt it has anything to do with the brain but I can attest that there are dietary reactions to it.

Happy to submit to any study (because I would also like to know what is wrong with me).

Sorry to hear that. Food research is super hard. Lots of people definitely have sensitivities to foods (like gluten) that have real effects whose mechanisms are not well understood. e.g. epilepsy is often really well controlled by a keto diet - wtf?

Understanding your own body and managing your diet accordingly is a great thing to do. Sad that it sometimes gets attacked as unscientific. Just because scientists looked for a broad food mechanism and didn’t find it doesn’t mean these effects aren’t real.

AFAIK there are few rare occurrences where MSG can cause reactions akin to an allergy. It's not an allergy per se given that there's no immune reaction involved though.

This phenomenon is rare but well documented, albeit not very understood. Sucks though.

Is there a chance you are sensitive to the sodium part of MSG?

I believe that, in addition to the blood pressure issues some people have, some react quite strongly to higher salt levels in food.

I eat salt regularly, so probably not, and I can eat other (softer) cheeses, and I can eat potato chips but not flavored ones with MSG (this was actually how I discovered MSG might be a trigger). So I am very confident that it has to do with glutamate.

OK, fair enough. It was just something I was pondering.

One thing I know for a fact is that, the actual MSG, even in small liquid form is abrasive, more abrasive than liquid salt, that it can easily scratch metals. In liquid form, I believe that, microscopically, it is enough to cross between the blood-brain barrier. Also, upon ingestion, you get this sudden light-headedness feeling (of course, it varies) or obtuse feeling. The point is, if this material is abrasive enough that easily scratch metals, and can affect mental state, I think it might have been damaging to use (or for long-term), that you need to either stop using it, or lessen the use of it.

MSG is ionically bonded between the sodium and the glutamate ion. As soon as it's dissolved in water you no longer have MSG, you have a solution of sodium and glutamate ions. Chicken broth is also a solution high in sodium and glutamate ions. As far as the notion that even dissolved "in liquid form" it's abrasive, there's zero chance that that's true. It's an ionic compound, when it's dissolved in water, it's individual molecules floating around. Those glutamate ions also don't even really float around on their own either, water molecules are attracted to them and sort of ball up around them which is why reverse osmosis membranes can filter out sodium ions even though the pore size is much larger than the size of a sodium atom.

If you witnessed some MSG and some water causing a small scratch on some metal then either whatever you were using to rub it against the metal caused the scratch or it was something insoluble other than MSG that did it. Maybe silica was added as an anti-caking agent (which is completely safe, a tiny bit of sand dust is not going to hurt you if you aren't inhaling a bunch) and the particle size was coarse enough to leave a visible scratch, either way it's not possible for dissolved MSG to be abrasive.

But you don't have to take my word on the subject, here's a study on the subject. " Monosodium Glutamate in the Diet Does Not Raise Brain Glutamate Concentrations or Disrupt Brain Functions" https://www.karger.com/Article/FullText/494782

Well actually, there's no other way to rid yourself out of MSG, since it exists in tomatoes and anchovies for example.

You could replace MSG with carbon and it wouldn't change anything, so I hope that you're not basing anything important on that type of logic.