NuMedica L-Theanine Relaxation and Stress Relief. Naturally occurring, unique amino acid found in green tea leaves. NuMedica's L-Theanine is Suntheanine the most respected source and the one which has been used in scientific studies. L-Theanine may promote a sense of relaxation without causing drowsiness. It has also been found to promote healthy cellular function and reduce feelings of stress and anxiousness. L-Theanine may be useful in reducing the negative side effects of caffeine. Recommended Use: Take one capsule one or two times per day or as directed by your healthcare practitioner.