If you ask anyone why they prefer matcha over coffee, one of the most common answers involves how it makes them feel. People report feeling more focused but calm and energized but not anxious. That distinctive quality comes largely from a single compound called L-theanine.
L-Theanine Defined
L-theanine is a naturally occurring amino acid found almost exclusively in tea plants, particularly in Camellia sinensis, the plant used to make green tea, white tea, black tea, and matcha. It is not classified as an essential amino acid, but its effects on the brain and nervous system are well-documented and genuinely useful.
How L-Theanine Works in the Brain
L-theanine crosses the blood-brain barrier and influences neurotransmitter activity. It increases levels of gamma-aminobutyric acid (GABA), serotonin, and dopamine, which are chemicals associated with mood regulation, relaxation, and focus. It also promotes alpha brainwave activity, the state linked to calm alertness that you might experience during meditation or light creative work.
Synergy With Caffeine
L-theanine's most celebrated effect is its relationship with caffeine. On its own, caffeine can cause jitteriness, elevated heart rate, and anxiety for many people. When paired with L-theanine as it naturally is in matcha, the amino acid softens caffeine's stimulant effects, resulting in smoother, more sustained energy without the crash. Researchers call this the L-theanine and caffeine combination effect, and multiple studies support its benefits for attention, reaction time, and mood.
How Matcha Maximizes L-Theanine
Because matcha involves consuming the entire tea leaf rather than just steeping it, you get significantly more L-theanine per serving than you would from brewed green tea. Shade-growing the tea plants before harvest further increases L-theanine content, which is why high-quality ceremonial grade matcha tends to produce a more noticeably calm focus than lower-grade versions.
L-theanine is a big part of why matcha feels the way it does. It’s also a big part of why we take the ceremonial grade side of Shinzo Matcha so seriously. The better the leaf, the more L-theanine ends up in your cup.
Frequently Asked Questions
What does L-theanine do?
L-theanine promotes calm alertness by increasing GABA, serotonin, and dopamine levels and stimulating alpha brainwave activity. It reduces the jittery side effects of caffeine while sharpening focus and reducing stress.
How much L-theanine is in matcha?
A standard serving of matcha contains approximately 20 to 45mg of L-theanine (each ceremonial grade pack from Shinzo Matcha contains 3 grams of matcha/65mg of L-theanine), significantly more than brewed green tea due to whole-leaf consumption and the shade-growing process that boosts its production.
Is L-theanine safe to consume daily?
Yes. L-theanine as found in matcha is considered safe for daily consumption. It is a naturally occurring compound with a well-established safety profile and no known side effects at normal serving sizes.
Can I get L-theanine from regular green tea?
You can, but in smaller amounts. Because matcha involves consuming the entire ground leaf rather than steeping and discarding it, you get meaningfully more L-theanine from matcha per serving.
Sources
- Giesbrecht T, Rycroft JA, Rowson MJ, De Bruin EA. The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness. Nutr Neurosci. 2010;13(6):283-290. Available at: https://pubmed.ncbi.nlm.nih.gov/21040626/
- Kahathuduwa CN, Dassanayake TL, Amarakoon AMT, Weerasinghe VS. Acute effects of theanine, caffeine and theanine-caffeine combination on attention. Nutr Neurosci. 2017;20(6):369-377. Available at: https://pubmed.ncbi.nlm.nih.gov/26869148/
- Kelly SP, Gomez-Ramirez M, Montesi JL, Foxe JJ. L-theanine and caffeine in combination affect human cognition as evidenced by oscillatory alpha-band activity and attention task performance. J Nutr. 2008;138(8):1572S-1577S. Available at: https://pubmed.ncbi.nlm.nih.gov/18641209/
- Hidese S, Ogawa S, Ota M, et al. Effects of L-Theanine Administration on Stress-Related Symptoms and Cognitive Functions in Healthy Adults: A Randomized Controlled Trial. Nutrients. 2019;11(10):2362. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6836118/
- Dassanayake TL, Wickramasinghe AN, Kahathuduwa CN, Weerasinghe VS. High-dose L-theanine–caffeine combination improves neurobehavioural and neurophysiological measures of selective attention in acutely sleep-deprived young adults: a double-blind, placebo-controlled crossover study. Br J Nutr. 2025\. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC12491391/
Disclaimer: The statements in this blog post have not been evaluated by the Food and Drug Administration. The information provided here is for educational purposes only and should not be considered as medical advice. Consult with a qualified healthcare professional before making any dietary or lifestyle changes.