The Baseline Shift: How 4 Weeks of L-Theanine Enhances Mental Health and Verbal Focus
- 4 days ago
- 1 min read
A landmark 2019 study published in Nutrients conducted a randomized, double-blind, placebo-controlled crossover trial to investigate the long-term (4-week) effects of daily L-theanine supplementation. Unlike previous studies that focused on acute, one-time doses, this research measured how consistent use affects a non-clinical, healthy population.
The researchers analyzed 30 adults taking 200 mg/day of L-theanine and found significant improvements across three key mental health domains:
Reduction in Stress-Related Symptoms: Participants reported a statistically significant decrease in scores on the Self-rating Depression Scale (SDS) and the State-Trait Anxiety Inventory. This suggests that chronic use of L-theanine helps "lower the floor" of daily anxiety and mood fluctuations.
Improved Sleep Quality: Using the Pittsburgh Sleep Quality Index (PSQI), the study noted significant reductions in sleep latency (time to fall asleep) and sleep disturbances. Importantly, this was achieved without the use of sedative medications, highlighting L-theanine's role in supporting natural sleep architecture.
Cognitive Enhancement (Verbal Fluency): One of the study's most unique findings was an increase in verbal fluency and executive function. Participants showed a improved ability to recall words and process complex information, particularly those who started with lower baseline scores.
The study concluded that a daily 200 mg dose is a safe and effective way to bolster mental resilience and cognitive clarity in the general population.
Article: Effects of L-Theanine Administration on Stress-Related Symptoms and Cognitive Functions in Healthy Adults: A Randomized Controlled Trial
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