Also called theanine, L-theanine is a free amino acid found almost exclusively in tea plants, especially green tea. It is the predominant amino acid in green tea leaves. Specialists have found that L-theanine gives tea its characteristic umami or fifth taste. Tea tasters rate the umami taste most highly as it is considered to be the single most important determinant of tea quality. Theanine has also been discovered in a species of the edible mushroom Boletus badius. Theanine is also used in dietary supplements, particularly for mental alertness and weight loss. 

L-theanine is present in both black and green tea, although more common in the latter. It is responsible for tea’s relaxing effect. L-theanine is probably the most valuable tea component, as experts have shown that it is the single most important marker of quality in green tea. Scientific studies, performed using electroencephalography, have discovered that theanine mutes the effect of caffeine, which is why tea doesn’t have the jitteriness of coffee. Researchers have found that L-theanine works by supporting the formation of gamma-aminobutyric acid. Gamma-aminobutyric acid blocks the release of the neurotransmitters dopamine and serotonin to promote a state of deep relaxation and calm, while increasing sensations of pleasure. L-theanine has also been found to directly stimulate the production of alpha brain waves, which are associated with deep states of relaxation and enhanced mental clarity. A study demonstrated that L-theanine could help healthy people to feel more tranquil, and which could mean possible future benefit for treating anxiety disorders. Early evidence suggests that L-theanine could increase the effectiveness of certain chemotherapy medications and may decrease some of the side effects of such medications. 

Active reagent
The amino acid L-Theanine is the active reagent. It is believed to work in treatments for anxiety by increasing levels of gamma-aminobutyric acid (GABA), a brain chemical that is naturally calming. L-Theanine may also increase serotonin levels in the brain. It is thought that the substance may also protect nerves in the brain from damage seen with Alzheimer’s disease.  Scientists are currently investigating future uses of L-theanine for Alzheimer’s treatment or prevention.


  • Alpha Brain Waves – L-theanine promotes Alpha brain waves. The human brain has four wave patterns, each of them associated with a different state of mind: in Delta brain waves, you are sleeping deeply, in Theta brain waves, you are dozing away, in Alpha brain waves, you are relaxed yet alert, and in Beta brain waves, you are awake and very excited, anxious, or stressed. Alpha waves are ideal for concentration, and relaxation – in sport’s terminology, entering a state dominated by Alpha waves is known as entering “the zone.” Numerous human trials have shown that theanine can promote alpha brain waves, putting you in a relaxed, yet alert state without causing drowsiness.
  • Dopamine – Dopamine is a hormone that is associated with a feeling of well-being. It is a neurotransmitter that is released during pleasurable activities such as eating and sex. Further evidence of thiamine’s relaxing properties comes from studies that found that theanine increases dopamine levels in the brain.
  • Learning – Theanine increases concentration, a reason why monks and scholars incorporate tea drinking into meditation and study. It helps to relax your mind, allowing you to focus on the task at hand.
  • Blood Pressure – Studies show that theanine may bring high blood pressure back to normal. However, Theanine has no effect on normal blood pressure.
  • Immunity –  According to studies, L-Theanine also improves the body’s immune system. An antigen is a substance recognized as foreign by the body: bacteria, viruses and other harmful organisms all have antigens. T-Cells use these antigens to determine if the cells are foreign invaders or natural inhabitants. Studies have found that L-Theanine stimulates the production of antigens, increasing the body’s immunity against colds and flu.


  • Cancer: A study suggests that Theanine may help improve the quality of life of cancer patients by improving the efficacy of cancer drugs, and through its relaxing effects on the mind. Studies have found that theanine may have the following benefits for cancer patients – Increases the efficacy of anti-cancer drugs in tumors. Reduces the efficacy of anti-cancer drugs in other tissues and other side effects.Inhibits the growth of cancer tumors themselves. Hence, cancer patients may take theanine, either as a supplement or in tea form, to complement chemotherapy drugs and reduce their side effects.
  • Anxiety: The active component, Gamma-aminobutyric acid, blocks the release of the neurotransmitters dopamine and serotonin to promote a state of deep relaxation and calm. For an anxiety disorders, theanine may be used as a complementary medicine.
  • PMS: A study by the Institute of Traditional Medicine discovered that consuming 200 milligrams of theanine daily helps alleviate PremenstrualSyndrome.
  • Alzheimer’s Disease: It is thought that L-theanine might be beneficial for Alzheimer’s disease treatment and even prevention. This is because L-theanine seems to protect nerves in the brain from damage seen in Alzheimer’s disease.
  • Blood Pressure: Several studies suggest that L-theanine may be effective for lowering high blood pressure (hypertension).

Side effects
At this time, there are no known side effects of L-theanine. Most people consume L-theanine in tea form, and so there have been little studies on the long-term effect of L-theanine supplements on humans. If you experience any reactions to L-theanine, make sure to notify your healthcare provider, as he or she may want to report these problems. The L-theanine consumed in tea is considered safe – people have been drinking it for thousands of years!

L-Theanine is an amino acid found in tea that is known to calm the mind. By increasing alpha waves, its consumption puts the mind in a calm, relaxed state. L-Theanine is also known to lower blood pressure, boost the immune system and lessen the symptoms of PMS. Research on this essential chemical continues to bring to light further benefits, including using L-theanine as an alternative to Ritalin in children and adults, and as an anti-cancer agent in synergy with other cancer-fighting drugs. In tea, L-theanine mutes the negative side effects of caffeine, taking the edge off coffee and putting the drinker in an alert, but relaxed state.

Read more:
How to Calm Yourself Through A Storm
Hibiscus Tea: Health Enhancer And Natural Fat-Flush
Go Stress-Free With L-Theanine, The Naturally Relaxing Amino Acid