Managing Stress & Anxiety Levels with Phytochemical Compounds
Managing Stress & Anxiety Levels
with Phytochemical Compounds
Effects of Green Tea Amino Acid L-Theanine Consumption on the
Ability to Manage Stress and Anxiety Levels: a Systematic Review
The green tea amino acid, L-theanine (L-THE) is associated with several health benefits, including improvements in mood, cognition and a reduction of stress and anxiety-like symptoms.
This systematic review evaluated the effect of pure L-THE intake, in the form of orally administered nutritional supplements, on stress responses and anxiety levels in human randomised controlled trials.
Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist, 9 peer-reviewed journal articles were identified where L-THE as a supplement was compared to a control.
Our findings suggest that supplementation of 200-400 mg/day of L-THE
may assist in the reduction of stress and anxiety in people exposed to stressful conditions.
The reviewed studies presented evidence that green tea influences psychopathological symptoms (e.g. reduction of anxiety), cognition (e.g. benefits in memory and attention) and brain function (e.g. activation of working memory seen in functional MRI). The effects of green tea cannot be attributed to a single constituent of the beverage. This is exemplified in the finding that beneficial green tea effects on cognition are observed under the combined influence of both caffeine and l-theanine, whereas separate administration of either substance was found to have a lesser impact.
Despite this finding, longer-term and larger cohort clinical studies, including those where L-THE is incorporated into the diet regularly, are needed to clinically justify the use of L-THE as a therapeutic agent to reduce stress and anxiety in people exposed to stressful conditions.
Plant Foods Hum Nutr. 2020 Mar;75(1):12-23. doi: 10.1007/s11130-019-00771-5.