L-theanine is one of the few natural molecules that has gotten as much attention as it has. L-theanine, which is also called glutamylethylamide, comes from the leaves of the green tea plant Camellia sinensis. It gives tea a unique and delicious taste. [R] But besides making food taste better, this amino acid has a wide range of possible health benefits that have researchers all over the world interested.

L-theanine, an amino acid found abundantly in green tea leaves, has captivated researchers with its potential health benefits. Beyond its taste, this remarkable compound holds promise for a range of applications. From its ability to improve mental focus and promote rest to its antioxidant, immunological, stress support, and hepatoprotective properties, [R] L-theanine has garnered attention as a research chemical with a multitude of potential benefits. In this article, we will explore the fascinating world of L-theanine and its potential impact in research settings.

Key Features

RCD.Bio offers L-Theanine with the following specifications:

  • A purity of 98%, verified by third-party laboratory testing.
  • Available in 50g powder form


  • CAS Number: 3081-61-6
  • Molar Mass: 174.200 g·mol−1
  • Chemical Formula: C7H14N2O3
  • IUPAC Name: (2S)-2-Ammonio-5-(ethylamino)-5-oxopentanoate or N-Ethyl-L-glutamine
  • Synonyms: γ-L-Glutamylethylamide

How L-Theanine Works?

L-Theanine is a compound that is quickly absorbed in the gastrointestinal tract through specialized transporters. Once absorbed, it starts to exert its effects on the brain. One of the notable effects of L-Theanine is its ability to enhance alpha waves in the brain, which are associated with a relaxed state. This can help promote a sense of calmness and relaxation. After oral administration, the peak absorption of L-Theanine in rats occurs within 0.5 to 2 hours.[R]

In the kidneys, L-Theanine undergoes hydrolysis, a process that breaks it down into two components: glutamic acid and ethylamine. These breakdown products are then excreted from the body. It is believed that L-Theanine crosses the blood-brain barrier, a protective barrier that separates the bloodstream from the brain, using a specific transport mechanism that prefers the amino acid leucine. Once in the brain, L-Theanine acts as a donor of glutamic acid, which is an important neurotransmitter.[R]
Numerous studies have explored the potential benefits of L-Theanine, particularly in terms of its anxiolytic effects. Anxiolytic agents are substances that can reduce anxiety and stress. Animal neurochemistry research has indicated that L-Theanine has a positive impact on various receptors in the brain. It has been found to have an affinity for receptors such as AMPA, Kainate, and NMDA, which are involved in regulating neurotransmission. Furthermore, L-Theanine has been shown to increase levels of important neurotransmitters in the brain, including serotonin, dopamine, and GABA. These neurotransmitters play crucial roles in mood regulation and relaxation. [R]

It is important to note that the effects of L-Theanine may vary among individuals, and further research is needed to fully understand its potential benefits.

The scientific basis behind the benefits of L-Theanine

Numerous research investigations and trials on animals suggest that l-theanine may have a number of benefits. Despite the fact that professionals consider it to be generally safe, there is currently a dearth of high-quality human studies to back up its benefits and its usage.

Antioxidant Properties and Neuroprotection

A study investigated the potential of L-theanine (LT) to alleviate peripheral neuropathy induced by Vincristine (VCR) in rats. VCR was administered to rats to induce neuropathy, while LT was given at different doses. The researchers evaluated nerve function using electrophysiological measurements and examined various biomarkers in the sciatic nerve related to oxidative stress, inflammation, and apoptosis. The results showed that VCR caused pain, decreased nerve conduction velocity, increased oxidative stress, and neuroinflammation. However, LT administration significantly reduced pain, oxidative stress, and inflammation, while also showing neuroprotective and anti-apoptotic effects. These findings suggest that LT could be a potential adjunctive treatment for VCR-induced neuropathy. [R]

It is worth noting that further research is necessary to fully understand the mechanisms underlying LT’s antioxidant and neuroprotective effects. Additionally, the study was conducted in rats, and its findings may not directly translate to humans. Therefore, more studies are needed to determine the efficacy and safety of LT as a potential treatment for neuropathy in humans.

Working Memory

L-Theanine’s possible impact on working memory was recently investigated in a randomized, double-blind, placebo-controlled experiment. A battery of cognitive tests called Cognitrax was used on mixed gender of test subjects between the ages of 50 and 69. L-theanine reduced reaction times for attentional tasks and enhanced working memory performance by raising the percentage of correct responses and lowering the percentage of omission errors. According to the findings of this study, l-theanine may aid in boosting attention, which would subsequently enhance working memory and executive functioning. [R]

It is important to note that further research is required to fully understand the underlying mechanisms by which L-Theanine exerts its effects on working memory. Additionally, the study was conducted on a specific demographic group, and its findings may not directly apply to individuals of different age groups or cultural backgrounds. Therefore, more extensive research, including studies involving diverse populations, is needed to validate and generalize these findings.

Stress and Anxiety

Anxiety and stress are common experiences that can significantly impact an individual’s overall well-being. While occasional stress is a normal part of life, chronic stress and anxiety can have detrimental effects on physical and mental health. Therefore, finding effective ways to manage and alleviate these symptoms is of great importance.

L-Theanine has been the subject of several studies investigating its potential benefits in reducing stress and anxiety. Four of the five randomized controlled trials in a study that included 104 participants revealed that L-theanine reduced anxiety and stress in people who were in stressful settings. [R]These findings suggest that L-Theanine may have a calming effect on the nervous system, helping individuals cope with stressful situations.

Another study, also published in the Journal of Clinical Psychiatry, focused on people with schizophrenia or schizoaffective disorder. According to the study, L-theanine relieved symptoms and lowered anxiety while promoting a balanced stress response. [R]

While these findings are encouraging, more research is necessary to establish the efficacy of L-Theanine as an option for managing stress and anxiety.


The combination of L-Theanine and caffeine has gained attention due to its potential synergistic effects on cognitive function. L-Theanine, an amino acid found in green tea leaves, is known for its potential calming properties and relaxation without causing drowsiness. Caffeine, on the other hand, is a well-known stimulant that can increase alertness and attention.

A recent study has shed light on the potential of L-Theanine and caffeine combined to improve focus, particularly in challenging tasks. The study focused on young adults as test subjects and explored the effects of consuming L-Theanine (97 mg) and caffeine (40 mg) together.[R]


The immune system plays a critical role in protecting the body from harmful pathogens and infections. Strengthening the immune system is essential for overall health and well-being, particularly in preventing and combating various diseases. 

The potential role of L-Theanine in strengthening the immune system has been explored in several studies. In a journal of beverages, a study found that L-theanine may reduce the occurrence of upper respiratory tract infections. [R]

Catechins and theanine were tested in a recent randomized control experiment to see how well they prevented influenza among healthcare test subjects. The study concluded that senior test subjects could potentially benefit from the ingestion of green tea catechins and L-Theanine as a means of preventing influenza infections. [R]


L-theanine has also been associated with improving the anti-tumor effects of numerous chemotherapy drugs. These encouraging findings lead researchers to believe that L-theanine may also enhance the anticancer effects of chemotherapy. [R]

Additionally, specific cancer studies have been reported to suppress the growth of cancer cells. It includes:

  • Lung Cancer [R]
  • Leukemia [R]
  • Liver Cancer [R]
  • Ovarian sarcoma [R]
  • Prostate Cancer [R]

The results showed that theanine had weak antiproliferative effects on cancer combined with moderate apoptotic, antimetastatic, anti-migration, and anti-invasion effects. To determine theanine’s effectiveness in the prevention and suppression of cancer and to clarify the underlying mechanisms in the in vivo setting, more research is required. [R]


Hypertension is a common health condition that can increase the risk of various cardiovascular problems. Finding natural and effective ways to manage blood pressure is crucial for maintaining overall health and reducing the risk of associated complications.

The study focused on individuals whose blood pressure tended to increase after engaging in specific mental activities. L-Theanine was administered to the test subjects, and its impact on blood pressure was observed. The results of the study revealed that L-Theanine had a beneficial effect on the participants. It helped mitigate the rise in blood pressure that occurred after completing the mental tasks, suggesting its potential in managing hypertension. [R]

Although the study showed promising results, it is important to note that further research is needed to confirm and expand upon these findings. 


L-Theanine, a compound found in green tea, has been the focus of studies examining its potential effects on sleep. Several findings suggest that L-Theanine may promote relaxation, which could contribute to sleep longer.

In one study, both animal and human subjects experienced improved sleep after consuming L-Theanine at dosages of 250 mg and 400 mg. These dosages were found to have a significant positive impact on sleep duration and quality. [R]

Another study found that a dosage of 200 mg of L-Theanine helped promote sleep by lowering the resting heart rate. By inducing a state of relaxation and reducing physiological arousal, L-Theanine may contribute to a more peaceful and restful sleep experience.[R]

L-theanine may make it easier for boys with attention deficit hyperactivity disorder (ADHD) to fall asleep. In a double-blind trial, the effects of L-theanine were investigated on 98 boys between the ages of 8 and 12. A randomized group was given chewable L-theanine pills twice a day at a dosage of 100 mg. The recipient group received a placebo. After six weeks, the L-theanine group slept for longer and more soundly. The results are encouraging, but more research is required before it can be deemed safe and advantageous, especially for children. [R]

Additionally, individuals with schizophrenia have reported improved sleep quality after taking L-Theanine. Sleep disturbances are common among individuals with schizophrenia, and L-Theanine may offer a potential avenue for addressing this issue.[R]

Preliminary studies suggest that L-Theanine may have positive effects on sleep. However, more research is necessary to establish its safety and effectiveness in different populations.


The information presented here is for educational purposes only and should not be construed as medical advice. L-Theanine is intended for laboratory research use only and is not intended for human consumption.

While L-theanine is generally considered safe, there are a few precautions to keep in mind.

If you have a known allergy or sensitivity to tea or its components.  Furthermore, there is limited information available on the safety of L-theanine during pregnancy or breastfeeding. 

The information presented here is for educational purposes only and should not be construed as medical advice. L-Theanine is intended for laboratory research use only and is not intended as a supplement or to treat or cure any disease in human

Potential side effects in subjects

It may cause headaches, trouble staying asleep, nausea, irritability, and stomach pain. [R]

Where Can I Buy L-theanine Online?

When buying L-theanine, it is important to choose a reputable seller who provides quality products. At, each product is accompanied by a third-party-issued Certificate of Analysis showing the identification, purity, and concentration of our product. Some also offer L-theanine double strength as a dietary supplement or vitamin similar to melatonin but offers L-theanine not as prescription drugs but for laboratory research use only.


L-theanine is an amino acid found in tea leaves, known for its potential health benefits.  L-theanine is rapidly absorbed in the gastrointestinal tract and can improve alpha waves in the brain, promoting to relaxation. It is believed to function as a donor of glutamic acid to the body and has shown anxiolytic effects in animal studies. 

Research suggests that L-theanine may have positive effects on working memory, stress relief, anxiety, focus, immunity, cancer, hypertension, and sleep. However, more high-quality human studies are needed to confirm these benefits. 

Precautions should be taken for individuals with tea allergies, underlying health conditions, or those taking medications that may interact with L-theanine. Limited information is available on its safety during pregnancy and breastfeeding. Possible side effects include headaches, sleep disturbances, nausea, irritability, and stomach pain. 


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If for any reason you are not completely satisfied with the product you receive, please contact us at [email protected]. Our team is dedicated to ensuring customer satisfaction and will be happy to assist you.

PLEASE NOTE: All products offered by are strictly intended for laboratory and research purposes only. They are not intended for use on animals or humans.