In a sense, caffeine makes me more hyped and therefore makes me speak faster and we all know what happends when we speak fast............... we stutter more xD I find it somewhat difficult to relax myself so to speak while I am speaking when I have drunk caffeine/coffee a few hours ago. So in that sense Theanine helps with being more relaxed and that may make you more fluent but do not except it to be a cure if you normally are anxious while speaking anyways. (Not for you but for the people reading.) What is your observation OP?