BS in Nutrition
Food Science and Nutrition Department
Mental health disorders are a universal issue and affect millions of individuals every day. Anxiety is the most common type of mental disorder, affecting social, physical, and cognitive health. Although clinicians usually suggest prescriptive medications, they carry side effects, are expensive, and only acutely alleviate symptoms. As a result, recent interest has been directed towards nonconventional dietary therapies, including tea and its constituent L-theanine, for anxiolytic effects. Tea is the most prevalent beverage consumed after water; it is historically and globally accepted. The purpose of this literature review is to explore whether tea and its constituent L-theanine carry anxiolytic effects. To identify research in human subjects, PubMed was searched for human studies from 1999 through 2014 of the relation between tea, its constituent L-theanine, and anxiety. Seven studies (2 cross-sectional, 5 clinical) were identified as relevant to measuring anxiety either subjectively or objectively. Three clinical studies showed an effect of tea and L-theanine on anxiety, however they lacked sufficient quality to give confidence of a cause-effect relationship. Stronger studies showed show an inconsistent relationship between tea and its constituent, L-theanine, on anxiety. Due to anxiety’s high prevalence and health consequences, more clinical trials using systematic measurements for assessing exposures and outcomes in a large number of subjects need to be undertaken. One key research question that persists is whether L-theanine in isolation is similar to L-theanine found in tea. More valid research is needed before definite conclusions can be made about the consumption of tea and its constituent, L-theanine, for anxiolytic properties.