The prescription of nutraceuticals is often based on theory and pre-clinical evidence (in-vivo or in-vitro) that a substance might behave in a particular way. However, we don’t know if something works on living humans with a specific condition until we conduct clinical trials and observational studies. The following result from a recent clinical trial is an example of the clinical efficacy not aligning with the pre-clinical evidence.

In their recent double-blind placebo-controlled trial, Professor Jerome Sarris and colleagues found that adjunctive L-theanine compared to placebo had no improvement in anxiety symptoms nor insomnia severity in people with a diagnosis of generalised anxiety disorder (GAD). But, they also found that participants reported greater self-reported sleep satisfaction, which is a clinically meaningful outcome for people with GAD that needs further research.

It’s still too early to draw definitive conclusions on the effect of L-theanine on anxiety symptoms, more research needs to be done to verify the results of this study.

You can read the study L-Theanine in the Adjunctive Treatment of Generalised Anxiety Disorder: A Double-Blind, Randomised, Placebo-Controlled Trial in the Journal of Psychiatric Research.