L-Theanine: Uses, Dosage, How it Works, and More

L-Theanine Powder

In a world where stress is a common denominator for us all, natural remedies to support mental and physical well-being are increasingly useful. Enter L-Theanine, an exceptional amino acid known for its ability to promote relaxation and sharpen focus. 

This article delves into what L-Theanine is, its uses, research-backed benefits, its synergistic effects with caffeine, how it works, and safety considerations. Arm yourself with knowledge and navigate the world of supplements with confidence, making informed choices for a calmer, more focused, and well-balanced you.


What is L-Theanine? 

L-Theanine is an amino acid primarily found in tea leaves, and most abundantly in green tea. Unlike most amino acids, it is not used to build proteins but is known for its unique ability to promote relaxation without sedation. This makes it an exceptional supplement for those seeking calmness and improved mental clarity.


Uses of L-Theanine

L-Theanine, with its unique properties, has a variety of applications that extend beyond basic stress reduction. Here's a more detailed exploration of its diverse uses:

Enhanced Cognitive Function

Focus and Concentration 

L-Theanine, known to improve focus and concentration [1], is particularly useful in tasks that require sustained attention.

Memory Support 

There is evidence suggesting that L-Theanine may aid in working memory [16] and recall, making it beneficial for studying or complex cognitive tasks.

A study [2] published in the Journal of Medicinal Food in 2022 has shed light on the cognitive benefits of L-Theanine. The research findings suggest that L-Theanine may play a significant role in improving attention, which in turn enhances working memory and executive functions. This study adds to the growing body of evidence supporting the positive impact of L-Theanine on mental performance, particularly in areas critical for day-to-day cognitive tasks and decision-making.

Stress and Mood Management

Reducing Stress 

One of the primary uses of L-Theanine is to reduce psychological and physiological stress, helping individuals maintain calmness in high-pressure situations.

A recent study [3] has indicated that L-Theanine could play a significant role in promoting mental health, especially in the general population experiencing stress-related issues and cognitive impairments. The findings from this study highlight L-Theanine's potential as an effective natural supplement for enhancing mental well-being and functioning, offering a promising option for those grappling with the challenges of stress and cognitive difficulties.

Mood Improvement 

By modulating neurotransmitters, L-Theanine can have a positive impact on mood, possibly helping to alleviate symptoms of mild mood disorders [3].


Sleep and Relaxation

Improving Sleep Quality

Though not a sleep inducer, L-Theanine can help improve the quality of sleep by promoting relaxation and reducing the time it takes to fall asleep.

A study [4] published in the Journal of the American College of Nutrition in 2015 highlights the unique qualities of L-Theanine as a natural aid for sleep. The research points out that L-Theanine effectively promotes relaxation without leading to drowsiness, distinguishing it from traditional sleep inducers. Instead of acting as a sedative, L-Theanine enhances sleep quality through its anxiolytic (anxiety-reducing) properties. This comprehensive review supports the notion that L-Theanine is a safe and natural option for improving sleep, offering a valuable alternative for those seeking non-sedative aids to improve their sleep quality.

Promoting Relaxation Without Drowsiness

Unlike many relaxants, L-Theanine can induce a state of calm alertness [4], making it suitable for daytime use.


Physical Health

Cardiovascular Health 

Preliminary studies suggest that L-Theanine may have a beneficial effect on blood pressure and overall cardiovascular health [6].

Immune System Support 

Early research indicates that L-Theanine might boost the immune system, although more research is needed in this area.

A study [7] has shown that L-Theanine, a compound found in tea leaves, could have significant benefits for the immune system based on various cell and animal studies. It appears that L-Theanine helps regulate the body's immune responses, particularly in areas like inflammation, nerve damage, the intestinal tract, and even in tumor conditions. This is achieved through its influence on certain immune cells known as γδT lymphocytes, its role in the production of glutathione (a key antioxidant), and its impact on the release of various cytokines and neurotransmitters, which are important in the body's immune and nervous systems. Essentially, L-Theanine could play a crucial role in maintaining and regulating immune health at multiple levels.

L-Theanine For Mental Health

Anxiety and Panic Attacks 

L-Theanine has been used to help manage symptoms of anxiety and panic attacks due to its calming effects.

A study [8] has found that L-Theanine may help improve brain function, particularly in the hippocampus, which is a part of the brain important for memory and emotion. The study suggests that this benefit might be due to L-Theanine's ability to alter levels of certain chemicals in the brain, specifically glutamate and methionine. These changes appear to have a calming effect, potentially making L-Theanine helpful for reducing anxiety and managing panic attacks. However, the researchers note that more investigation is needed to fully understand how L-Theanine achieves these effects. This finding is significant as it indicates that L-Theanine could be a natural aid for those struggling with anxiety and panic attacks, by enhancing brain function in areas crucial for emotion regulation.


Some studies suggest potential benefits for depressive symptoms, but L-Theanine should not replace conventional treatment.

A recent study [9] explored the effects of L-theanine, at a dose of 2 mg/kg, on the brain chemistry of rats exhibiting signs of depression. The study used a model known as chronic unpredictable mild stress (CUMS) to simulate depressive-like behaviors in these rats. The results were promising, showing that L-theanine significantly improved these depressive behaviors. Specifically, it increased the levels of important neurotransmitters – serotonin (5-HT), norepinephrine, and dopamine – in key brain areas involved in mood regulation, such as the prefrontal cortex, nucleus accumbens, hippocampus, and striatum. Notably, in the hippocampus, dopamine levels saw a significant rise post L-theanine treatment.

These findings suggest that L-theanine could potentially have antidepressant-like effects, possibly by influencing these monoamine neurotransmitters in critical brain regions associated with depression. In simpler terms, L-theanine might help alleviate symptoms of depression by positively affecting the brain's chemical balance, particularly enhancing the levels of neurotransmitters that influence mood and emotional well-being.

Special Populations

Children with ADHD

There is emerging research suggesting that L-Theanine may help improve attention and self-regulation in children with ADHD.

A recent study [10] has found that taking 400 mg of L-Theanine daily is safe and can help improve sleep quality in boys who have ADHD. Sleep issues are often seen in those with ADHD, and poor sleep can even contribute to the condition. Therefore, L-Theanine could be a valuable addition to the treatment of ADHD in children, offering a safe way to enhance sleep without the use of traditional sleep medications.


For older adults, L-Theanine may be beneficial for maintaining cognitive health and managing age-related stress.

Everyday Well-being

Daily Stress Management

It is commonly used by individuals in high-stress jobs or lifestyles to manage daily stress and maintain a balanced mood.

Meditation and Yoga

Some use L-Theanine to enhance the relaxation and focus required for meditation and yoga practices.

L-Theanine with Caffeine Studies and Benefits

Matcha and Green Tea Leaves

Combining L-Theanine with caffeine, a common practice in nootropic supplements, has been shown to have synergistic effects. Studies indicate that this combination can:

  • Enhance cognitive performance more effectively than caffeine alone
  • Reduce the jitteriness and increased heart rate often associated with caffeine intake
  • Improve attention and reaction time

 A study [11] published in Nutritional Neuroscience in 2010 found that when L-Theanine and caffeine are taken together, they significantly improve cognitive performance. Specifically, the study showed that a combination of 97 mg of L-Theanine and 40 mg of caffeine not only enhanced accuracy in tasks requiring attention switching but also increased the participants' self-reported alertness.

Additionally, this combination was effective in reducing feelings of tiredness. These findings suggest that this specific amount of L-Theanine and caffeine can be particularly helpful in improving focus and attention during demanding mental tasks.

 Another study [5] published in the Journal of Medicinal Food revealed that a single dose of L-Theanine can notably enhance attention and working memory. Specifically, the study found that participants who took L-Theanine showed improved reaction times in attention-focused tasks, like the Stroop test. Additionally, they performed better in working memory tasks, with an increase in correct answers and a decrease in missed responses. Overall, this study suggests that L-Theanine could be beneficial in boosting attention, working memory, and executive functions, making it a promising supplement for cognitive enhancement.

Ideal L-Theanine to Caffeine Ratio

The optimal ratio of L-Theanine to caffeine typically ranges from 2:1 to 1:1. Tonicc’s L-theanine supplement contains 200 mg serving of L-Theanine, it pairs best with 100-200mg of caffeine. This ratio is ideal for maximizing the benefits while minimizing potential caffeine-related side effects.

How L-Theanine Works: A Deeper Insight

L-Theanine’s effectiveness can be attributed to its unique ability to cross the blood-brain barrier and influence brain chemistry. Here's a more detailed look at its mechanisms of action:

L-Theanine and Neurotransmitter Regulation

  • GABA Enhancement: L-Theanine increases the levels of Gamma-Aminobutyric Acid [12] (GABA), a key inhibitory neurotransmitter known for its calming effects. This increase in GABA helps reduce neuronal excitability, leading to a state of relaxed alertness.

  • Dopamine and Serotonin Modulation: It also affects the levels of neurotransmitters like dopamine and serotonin, which play significant roles in mood regulation, emotional well-being, and cognitive function. By modulating these neurotransmitters, L-Theanine can enhance mood and cognitive abilities.

Alpha Brain Waves Stimulation

  • Promoting Relaxation: L-Theanine stimulates the production of alpha brain waves [13], which are associated with a state of “wakeful relaxation.” This is the brain state often found during meditation and is linked to enhanced creativity, focus, and a sense of peaceful alertness.

 Stress Hormone Reduction

  • L-theanine and Cortisol Regulation: L-Theanine may help in reducing [14] the levels of cortisol, the body's primary stress hormone. By mitigating the body’s stress response, it contributes to a sense of relaxation and well-being.

 L-Theanine’s Neuroprotective Effects

  • Protecting Brain Cells: There is evidence that L-Theanine possesses neuroprotective [15] properties. It may protect brain cells against damage from stress and age-related neurodegenerative diseases.


Safety and Known Interactions

L-Theanine is generally considered safe and well-tolerated. However, it’s important to note:

  • Caution is advised for pregnant or breastfeeding women due to a lack of extensive research on these groups.
  • People with certain medical conditions or those taking prescription medications should consult with a healthcare provider before starting L-theanine supplementation.


L-Theanine is a promising natural supplement for individuals looking to manage stress, improve cognitive function, and maintain a balanced mood. Its ability to promote relaxation without sedation, especially when combined with caffeine, makes it a suitable choice for those facing high-pressure environments. While its safety profile is favorable, as with any supplement, it should be used responsibly and ideally under the guidance of a healthcare professional. If you are looking for an easy way to incorporate L-Theanine, and other stress busting ingredients into your routine, check out Daily Vitality, our one pump liquid nootropic and adaptogen supplement. 




  1. Baba, Y., Inagaki, S., Nakagawa, S., Kaneko, T., Kobayashi, M., & Takihara, T. (2021). Effects of l-Theanine on Cognitive Function in Middle-Aged and Older Subjects: A Randomized Placebo-Controlled Study. Journal of medicinal food, 24(4), 333–341. https://doi.org/10.1089/jmf.2020.4803
  2. Baba, Y., Inagaki, S., Nakagawa, S., Kaneko, T., Kobayashi, M., & Takihara, T. (2021). Effects of l-Theanine on Cognitive Function in Middle-Aged and Older Subjects: A Randomized Placebo-Controlled Study. Journal of medicinal food, 24(4), 333–341. https://doi.org/10.1089/jmf.2020.4803
  3. Hidese, S., Ogawa, S., Ota, M., Ishida, I., Yasukawa, Z., Ozeki, M., & Kunugi, H. (2019). Effects of L-Theanine Administration on Stress-Related Symptoms and Cognitive Functions in Healthy Adults: A Randomized Controlled Trial. Nutrients, 11(10), 2362. https://doi.org/10.3390/nu11102362
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  6. Li, M. Y., Liu, H. Y., Wu, D. T., Kenaan, A., Geng, F., Li, H. B., Gunaratne, A., Li, H., & Gan, R. Y. (2022). L-Theanine: A Unique Functional Amino Acid in Tea (Camellia sinensis L.) With Multiple Health Benefits and Food Applications. Frontiers in nutrition, 9, 853846. https://doi.org/10.3389/fnut.2022.853846
  7. Chen, S., Kang, J., Zhu, H., Wang, K., Han, Z., Wang, L., Liu, J., Wu, Y., He, P., Tu, Y., & Li, B. (2023). L-Theanine and Immunity: A Review. Molecules (Basel, Switzerland), 28(9), 3846. https://doi.org/10.3390/molecules28093846
  8. Ogawa, S., Ota, M., Ogura, J., Kato, K., & Kunugi, H. (2018). Effects of L-theanine on anxiety-like behavior, cerebrospinal fluid amino acid profile, and hippocampal activity in Wistar Kyoto rats. Psychopharmacology, 235(1), 37–45. https://doi.org/10.1007/s00213-017-4743-1
  9. Shen, M., Yang, Y., Wu, Y., Zhang, B., Wu, H., Wang, L., Tang, H., & Chen, J. (2019). L-theanine ameliorate depressive-like behavior in a chronic unpredictable mild stress rat model via modulating the monoamine levels in limbic-cortical-striatal-pallidal-thalamic-circuit related brain regions. Phytotherapy research : PTR, 33(2), 412–421. https://doi.org/10.1002/ptr.6237
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  12. Raj, K., Gupta, G. D., & Singh, S. (2022). l-Theanine ameliorates motor deficit, mitochondrial dysfunction, and neurodegeneration against chronic tramadol induced rats model of Parkinson's disease. Drug and chemical toxicology, 45(5), 2097–2108. https://doi.org/10.1080/01480545.2021.1907909
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