L-Theanine

Overall Health Benefits of L-theanine

• Improves Cognitive Function [1-13]
• Improves Mood [14-23]
• Fights Stress [24-27]
• Improves Sleep Quality and Fights Insomnia [28-34]
• Boosts Immune Function [35-42]
• Fights Cancer and Aids in Cancer Treatment [43-50]

How does L-theanine Work?

This amino acid impacts nerve impulses and aids in the release of brain neurotransmitters. A change in the process of nerve cell communication and balance of these brain chemicals is thought to positively affect overall mood and reduce stress levels.

Proven Health Benefits of L-theanine

Improves Cognitive Function

L-theanine is a nootropic or cognitive enhancer. Studies show that consumption of this compound can help improve various cognitive parameters:

1. In young adults, supplementation with 97 mg of L-theanine improved focus attention during a demanding cognitive task. [1]
2. In healthy male volunteers, L-theanine supplementation at dose of 200 mg improved cognitive and neurophysiological measures of selective attention. [2]
3. In men and women with mild cognitive impairment, a combination of L-theanine and green tea extract improved memory in a test assessing recognition and increased the levels of brain theta waves, an indicator of cognitive alertness. [3]
4. In healthy volunteers, L-theanine administration improved speed and accuracy of performance of the attention-switching task and reduced the rate of errors in the memory task. [4]
5. In healthy, young participants, L-theanine administration at a dose of 500 mg improved mental alertness and increased alpha activity in the electroencephalogram, which is indicative of improved attention. [5]
6. L-theanine administration at a dose of 250 mg led to faster reaction time and numeric working memory reaction time and improved sentence verification accuracy in healthy human subjects. [6]
7. In healthy volunteers, L-theanine supplementation improved working memory and performance task. [7]
8. In elderly persons with normal or slight cognitive dysfunction, ingestion of powdered green tea containing a high L-theanine concentration significantly reduced cognitive decline. [8]
9. A study found that L-theanine may provide effective prophylaxis and treatment for Alzheimer’s disease by preventing programmed cell death (apoptosis) of brain cells. [9]
10. In rats, ingestion of water containing 0.3% L-theanine for 3 weeks was associated with improved recognition memory. [10]
11. In animal models, L-theanine improved learning and memory possibly through its neuroprotective effects. [11]
12. In a mouse model of Alzheimer’s disease, L-theanine ameliorated memory impairment. [12]
13. In rats, ingestion of L-theanine for 3 weeks ad libitum improved learning and memory. [13]

Improves Mood

Numerous high quality studies show that L-theanine plays a key role in mood support by positively affecting the production of neurotransmitters:

1. In patients with major depressive disorder, L-theanine administration for 8 weeks improved depressive symptoms, anxiety, sleep disturbance and cognitive impairments. [14]
2. In patients with schizophrenia, supplementation with 400 mg L-theanine along with regular medications for 8 weeks resulted in significant reductions in anxiety and general symptoms of psychopathology. [15]
3. A dose of 250 mg per day of L-theanine also improved symptoms and sleep in schizophrenic patients. [16]
4. Combination of L-theanine and the hormone pregnenolone improved negative symptoms in schizophrenic patients. [17]
5. Administration of 200 mg of L-theanine was associated with increased brain alpha waves (stimulate creativity and reduce depression) and prolonged periods of relaxation. [18-19]
6. L-theanine may also help improve mood by stimulating production of the relaxing neurotransmitter Gamma-Aminobutyric Acid (GABA). [20]
7. In patients with generalized anxiety disorder, L-theanine treatment was associated with improved symptoms. [21]
8. In animal models, L-theanine supplementation reduced symptoms of anxiety. [22]
9. In a chronic unpredictable mild stress rat model, L-theanine ameliorated the depressive-like behaviors. [23]

Fights Stress

L-theanine does not only possess potent antidepressant and anti-anxiety properties, studies show that this powerful nootropic can also fight stress and its detrimental effects on the body:

1. In healthy participants, L-theanine administration reduced stress responses and cortisol levels. [24]
2. In participants who underwent a series of stress test, L-theanine intake resulted in anti-stress effects as evidenced by reduced heart rate and salivary immunoglobulin A. [25-26]
3. In healthy adults aged 18-40, L-theanine administration reduced subjective stress response. [27]

Improves Sleep Quality and Fights Insomnia

With its calming and anti-stress effects, L-theanine can benefit people suffering from sleeping difficulties. Studies show that administration of L-theanine has positive effects on sleep quality and quantity:

1. In patients with attention deficit hyperactivity disorder (ADHD), L-theanine treatment was associated with higher sleep percentage and sleep efficiency scores. [28-29]
2. In patients with schizophrenia, L-theanine treatment for 8 weeks improved sleep quality. [30]
3. In patients with major depressive disorder, L-theanine administration improved scores on Pittsburgh Sleep Quality Index (PSQI). [31]
4. In patients with generalized anxiety disorder, L-theanine treatment was associated with greater self-reported sleep satisfaction. [32]
5. In animal models, L-theanine treatment was associated with improved NREM (non-rapid eye movement) sleep. [33]
6. In rats, L-theanine reversed caffeine-induced sleep disturbances. [34]

Boosts Immune Function

L-theanine can also ward off a multitude of diseases. Studies show that L-theanine has immune-boosting properties:

1. In well-trained men, L-theanine supplementation once daily for 2 weeks restored natural killer cell activity. [35]
2. In long-distance runners, L-theanine supplementation for 7 days reduced the alteration of the immune state. [36]
3. A study found that L-theanine can significantly decrease the incidence of upper respiratory tract infections. [37]
4. In patients who had abdominal surgery, L-theanine treatment was associated with reduced intestinal inflammation. [38]
5. L-theanine improves immunity by boosting the activity of T cells, which are immune cells that protect against infection and tumors. [39-40]
6. One study found that regular consumption of L-theanine was associated with increased production of T cells. [41]
7. In rats, L-theanine administration at a dose of 400 mg/kg improved immune function by altering the Th2/Th1 cytokine balance, increasing dopamine levels, and decreasing corticosterone levels. [42]

Fights Cancer and Aids in Cancer Treatment

According to studies, L-theanine also has potent anti-cancer properties that can help combat various types of malignant cells in the body:

1. In patients undergoing chemotherapy, L-theanine reduced doxorubicin-induced adverse reactions. [43]
2. In gastrointestinal cancer patients, oral administration of L-theanine reduced the side effects of chemotherapy. [44]
3. In human liver cancer cell lines, L-theanine treatment greatly reduced cancer cell migration. [45]
4. In human lung cancer and leukemia cell lines, L-theanine treatment suppressed metastasis by targeting signaling pathways involved in cancer cell growth. [46-47]
5. In human liver and cervical cancer cell lines, L-theanine treatment induced programmed cell death. [48]
6. A study found that L-theanine may help suppress cancer growth and reduce cancer prevalence through its antioxidant properties. [49]
7. In mice with ovarian cancer, L-theanine enhanced the antitumor activities of chemotherapeutic drugs such as anthracyclines, cisplatin and irinotecan. [50]

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