L-Theanine - 60 Capsules | Pure Encapsulationsl Theanine features high quality theanine as Suntheanine, the brand which has been used in scientific studies. l Theanine is a constituent of green tea. Suntheanine provides only l theanine whereas other brands may not be as pure or active. In one study, only Suntheanine contained pure l theanine whereas generic brands contained D theanine. Research shows pure l theanine is better absorbed and metabolised. Each vegetarian capsule provides 200 mg