Interesting, thanks for sharing your experience. I googled a bit and found this : While glutamate is the brain’s most important excitatory neurotransmitter, L-theanine binds to the same brain cell receptors and blocks them to glutamate’s effects. This action produces inhibitory effects.1,2 That inhibition to brain overactivity has a calming, relaxing effect in which anxiety fades.3 http://www.lifeextension.com/magazine/2016/3/brain-benefits-of-l-theanine/page-01 (Dont shoot me, yeah, the URL looks not that scientific) If i remember correctly, us stutterers have overactivity in the speech motor complex and underactivity in the auditory. So it would kind of make sense. More uneducated guesses? Opinions? Im gonna try it out too in a week or so.