Interesting concept, shame it&#x27;s limited to the US (understandable due to dubious legality of shipping unclassified chemicals between jurisdictions).<p>Been interested by the apparent &#x27;attention enhancing&#x27; qualities of L-Theanine, although not gone as far as purchasing any. By coincidence someone got me into drinking green tea a couple of weeks ago, I haven&#x27;t noticed any visible change. Although I expect my problem is concentrating on the right thing, rather than simply failing to concentrate.