Here’s some quick food for thought: isn’t it funny that we consider MSG a bad thing (due to it being monosodium glutamate, and glutamate is an excitatory neurotransmitter), and many people have problems with it-yet the two most beneficial gut symbionts we know of actually consume MSG and metabolize it into GABA, which is the brain neurotransmitter that is calming and inhibitory…almost like MSG sensitivity could be a marker for poor levels of Lactobacillus and Bifidobacteria, isn’t it? And, people sensitive to MSG often have problems with excitotoxicity, where the brain is overstimulated by the MSG. Almost like? yes, not enough inhibitory GABA. hmmm.
When that chemical you avoid, is food to your good gut bacteria…
The Symbiont Factor Blog 
Nice article on gut food