L-theanine, also known as L-γ-glutamylethylamide and N⁵-ethyl-L-glutamine is a non-protein amino acid that’s naturally occurring in some plants and fungus. Theanine is the name given to L-theanine when it is used as a food supplement, which is permitted in many international locations. Most famously L-theanine was found to be an active ingredient in green tea…