UserX
My brother has the same feeling that many have had. There are folks who are known
Mono-Sodium-Glutamat (Natrium Glutamat) sensitive not having an issue with Superfood or Brewer's yeast at all.
MSG is an isolated chemical; brewer's yeast while high in glutamate has many other amino acids in its profile prohibiting an unbalanced absorption of any single AA. In our brains we have AA transporters that act as a gateway to the CSF (brain fluid) aka the blood-brain barrier. These transporters have a staturation point where they are "booked" and cannot let more AA's in. That's why when you take melatonin (derivative of tryptophan) or tyrosine you need to not eat protein with them so that you keep all the transporters open to get the drug like effect. Once you eat other AA's you won't get the absorption necessary to produce a drug-like effect.
I still think the label 'yeast nutrient' is different from 'nutritional yeast' because items that would contain yeast nutrient are probably heavily processed while nutritional yeast (at least the brand that I have) is very minimally processed.
I asked Doc Fuhrman whether brewer's yeast could have a neurotoxic effect. He said unless I was eating ridiculous amounts of it by itself, he didn't see it as a problem as long as the brand I was getting didn't have a whole bunch of bulls*&t added to it. The brewer's yeast I get is from Lewis labs and its minimally processed and just brewer's yeast. Its also NON-fermentable. Superfood herbdoc.com and Vitalerb's
http://devoted.to/drchristopher nutritional yeast, as you know, are minimally processed.
As I go through med-school I've learned that when people make statements they need to back it up in some way. That way you can understand their logic and make a decision as to whether you agree with them or not. For instance, flavor enhancers are not all bad.
Mono-Sodium-Glutamat (Natrium Glutamat) is an unnatural isolate developed in a lab that has definite neurotoxicity (proven to destroy neural retinal cells). It was originally derived from a seaweed called Kombu that is used in traditional asian cooking as a flavor enhancer. I would have no reservations eating something "enhanced" with kombu, I would however, have issues with MSG. The end all be all is that if I sawsome proof or at least some sort of logic that was reasonable enough to demonstrate that a Lewis Lab's type nutritional yeast is neurotoxic I would stop. But I haven't and like you I was concerned about it and did some research on it and came to the conclusion that its fine. This could always change.
If you do come across some good logic or proof, feel free to send it my way. One last thing I have been using about 2.5 servings of Brewer's yeast almost everyday for around 3 years now. I have never had a side-effect (headaches, dizziness, confusion, etc...) after eating it OR any withdrawal effects when occasionally I would go off of it for a week or 2. You would figure that something that is neurotoxic would effect a sensitive person like me with side effects or at least some withdrawal symptoms when I would stop eating it.
Mike
http://www.bobmantz.com