L-Theanine
The Zen Amino
L-Theanine is a naturally occurring amino acid found almost exclusively in green tea. Revered for centuries in Japanese and Chinese cultures, it’s known for promoting a calm, focused mental state—often described as “relaxed alertness.”
Modern research confirms what monks and tea masters have known for centuries: L-Theanine helps balance mood and focus, making it a favorite for those looking to stay grounded in high-stimulus environments or during mentally demanding tasks.
*The research below is provided for informational purposes only and does not refer to this specific product.
The Research:
Calm Focus and Mental Clarity
Study: Nobre, A. C., et al. (2008). L-theanine, a natural constituent in tea, and its effect on mental state.
Journal: Asia Pacific Journal of Clinical Nutrition
Key Takeaway: L-Theanine increased alpha brain wave activity (associated with relaxed wakefulness) and improved attention during cognitive tasks.
Why it matters: Supports use of L-Theanine for calm alertness and better task performance under pressure.
Anxiety and Stress Reduction
Study: Kimura, K., et al. (2007). L-Theanine reduces psychological and physiological stress responses.
Journal: Biological Psychology
Key Takeaway: A single dose of L-Theanine significantly reduced heart rate and salivary cortisol during stress-inducing tasks.
Why it matters: L-Theanine may help reduce acute stress without impairing mental performance.
Enhanced Attention When Combined with Caffeine
Study: Haskell, C. F., et al. (2008). The effects of L-theanine, caffeine and their combination on cognition and mood.
Journal: Biological Psychology
Key Takeaway: L-Theanine combined with caffeine improved speed and accuracy in attention-switching tasks and reduced tiredness.
Why it matters: Ideal for consumers seeking clean, focused energy without overstimulation.
Sleep Quality Support
Study: Lyon, M. R., et al. (2011). Effects of L-theanine (Suntheanine®) on stress-related symptoms and cognitive functions in healthy adults.
Journal: Alternative Medicine Review
Key Takeaway: Participants taking L-Theanine reported better sleep quality and lower stress scores after four weeks.
Why it matters: Suggests L-Theanine supports deeper, more restorative sleep, even under stress.
Safety and Tolerability
Study: Yokogoshi, H., et al. (1998). Safety evaluation of L-theanine in rats and humans.
Journal: Bioscience, Biotechnology, and Biochemistry
Key Takeaway: L-Theanine was well tolerated at high doses with no adverse effects observed in animals or humans.
Why it matters: Confirms the safety of L-Theanine as a daily-use ingredient.