I think the scientific approach of isolating a specific element in that way might be problematic because it ignores interactions with other ingredients and food preparation methods.
I would not have thought that isolation would be problematic, unless you are aware of a specific interaction of MSG with some other food ingredients that worsens the effects of MSG.
How detailed were your tests? I think some people:
* react to the excess gluten that is often added to supermarket bread to increase volume and consistency,
* others may be reacting to folic acid added to non-organic flour,
* some may have problems with modern hybridized wheat but no trouble with one or more heirloom wheats (such as Spelt, Kamut, or Red Fife),
* while still others have trouble with modern baked bread but don't have any difficulty with properly made, long fermented sourdough bread (organic preferably just in case other additives are causing problems.)
Through my testing of different gluten-containing foods, what I found was by far the worse culprit (in terms of the severity of the depression it precipitated), was any sources thickened with wheat flour (for example, a curry dish whose source is thickened with wheat flour, or a salad dressing thickened with wheat flour).
Then the next severe was supermarket bread. I have not specifically tested different bread types though.
The least severe was the wheat found in pasta (
durum wheat).
(I think the Kamut®
Khorasan wheat you mentioned is very similar to durum wheat: one appears to be
Triticum turgidum subsp. durum, and the other
Triticum turgidum ssp. turanicum.)
I am not sure why wheat flour was by far the worst, but I wonder if it is because flour comprises very fine particles, which in effect may have a larger surface area, and so places more gluten in contact with my intestinal surfaces, and the immune system apparatus found therein. But this is just a guess; I really do not know the answer.
The only thing I found of comparable severity to sources thickened with wheat flour was wheat beer (beer made with wheat rather than malted barley). Wheat beer tastes lovely, but boy did cause me nasty depression.
I had gluten sensitivity all my life, but only discovered it when I was 25 years old (from doing an exclusion diet). From then on I cut out all gluten, and this was something of a revolution in my life, because I no longer would suffer from these bouts of depression and dysphoria that would mysteriously appear in the evening.
However, since getting ME/CFS, around the age of 40, although my depression and anhedonia are at higher levels as a result (comorbid symptoms to ME/CFS),
I no longer seem to be gluten sensitive. That is to say, now with ME/CFS, I can eat gluten containing foods without them triggering an 8 hour bout of depression that they invariably did previously.
Why this change occurred is a mystery to me.
Dr Fasano's research on non-celiac gluten sensitivity I find very interesting (see
this post).