What is l theaninel theanine is an amino acid which can be found naturally in green teabenefits of l theaninel theanine is a naturally occurring amino acid that can be found in small quantities in a variety of foods for maximum benefits however it is necessary to supplement the diet with additional sources of l theanine in order to enjoy its full effects although l theanine is found in green tea it does not contain caffeine l theanine powder contains 100 l theaninewho is l theanine suita