L-Theanine by HealthwiseHealthwise L Theanine Promote your relaxation without feeling drowsy and simply unwind with Healthwise L Theanine. As a common anxiety and stress relief, L Theanine is a great assistant on tough days. Although mostly found in great tea, this HealthWise supplement contains L Theanine derived from corn and is not known to cause agitation. L Theanine is also known to increase focus and attention is paired with caffeine. Anxiety and stress relief.