Neurobiological effects of the green tea constituent theanine and its potential role in the treatment of psychiatric and neurodegenerative disorders.
Level 5 - mechanism / opinion, no new human data
Narrative review synthesizing preclinical mechanisms and heterogeneous clinical findings without systematic methodology.
PubMed 23883567 · doi:10.1179/1476830513Y.0000000079
What was done
This was a narrative review synthesizing literature on the neurobiological, neurochemical, and pharmacological mechanisms of the green tea constituent theanine (n-ethylglutamic acid) and its potential clinical applications across psychiatric, cognitive, and neurodegenerative conditions.
What was found
The abstract provides no quantitative data or effect sizes. It reports that theanine crosses the blood-brain barrier and exhibits anxiolytic, cognitive-enhancing, and neuroprotective properties. Mechanisms and effects noted include upregulation of inhibitory neurotransmitters, possible modulation of serotonin and dopamine, increased brain-derived neurotrophic factor, alterations in NMDA-dependent and independent CA1 long-term potentiation, and selective increases in alpha brain wave activity during mental tasks. Potential therapeutic roles discussed include neuroprotection in cerebral infarct/injury, schizophrenia augmentation, depression models, ADHD, and theoretical applications in other psychiatric disorders.
Why it matters
This review outlines the multifaceted central nervous system mechanisms of theanine, summarizing evidence for its potential as a nutraceutical across psychiatric and neurological disorders.
Limits
As a narrative review, it lacks a systematic search protocol, formal quality assessment, or meta-analytic quantification. Much of the reviewed literature relies on animal models, mechanistic reasoning, or theoretical extrapolations rather than established human clinical trials. No sample sizes or numerical results are reported in the abstract.
Cited by
- supports L-theanine crosses the blood-brain barrier.