Theanine
Encyclopedia
Theanine also gamma-glutamylethylamide or 5-N-ethyl-glutamine, is an amino acid
and a glutamic acid
analog commonly found in tea
(infusions of Camellia sinensis
), primarily in green tea
, and also in the basidiomycete mushroom Boletus badius
and in guayusa
. More specifically, this compound is called L-theanine, being the levorotary enantiomer
. In 1950, the tea laboratory of Kyoto successfully separated theanine from gyokuro
leaf, which has high theanine content. Theanine is an analog to glutamine
and glutamate, and can cross the blood-brain barrier
. It is sold in the US as a dietary supplement, and is FDA confirmed as Generally recognized as safe
(GRAS). The Japanese Ministry of Health and Welfare approved the use of theanine for universal consumption in 1964.
, theanine has psychoactive
properties. Theanine has been shown to reduce mental and physical stress
, and improves cognition and mood in a synergistic manner with caffeine
.
While structurally related to the excitatory neurotransmitter glutamate, theanine only has weak affinity for the glutamate receptor on postsynaptic cells. Rather, its primary effect seems to increase the overall level of the brain inhibitory transmitter GABA
. Theanine also increases brain dopamine
levels and has a low affinity for AMPA
, kainate
and NMDA receptor
s. Its effect on serotonin
is still a matter of debate in the scientific community, with studies showing increases and decreases in brain serotonin levels using similar experimental protocols. It has also been found that injecting spontaneously hypertensive mice with theanine significantly lowered levels of 5-hydroxyindoles in the brain. Researchers also speculate it may inhibit glutamic acid
excitotoxicity
. Theanine also promotes alpha wave
production in the brain.
Studies on test rats have shown even repeated, extremely high doses of theanine cause little to no harmful psychological or physical effects. Theanine showed neuroprotective effects in one rat study.
A placebo-controlled trial has shown adding theanine to ongoing antipsychotic
medication is helpful in reducing some symptoms of schizophrenia
.
Several beverage manufacturers are selling drinks containing theanine and are marketing them as drinks to help people focus and concentrate, while other manufacturers claim relaxing and tranquillizing properties.
L-Theanine has been shown to both reduce the time that it takes a person to fall asleep as well as decrease the number of nighttime awakenings.
, included a four-week trial with 11 coffee drinkers and 10 tea drinkers, who consumed 600 milliliters of coffee or black tea daily. Blood sample analysis found the production of antibacterial proteins was up to five times higher in the tea drinkers, an indicator of a stronger immune response.
consumed by the average Japanese tea drinker per day contains about 20 mg of the substance, there are no studies measuring the amount of theanine being extracted by typical preparation methods, or the percentage lost by discarding the first infusion. Therefore, with the Japanese being exposed to possibly much less than 20 mg per day, and Europeans presumably even less, pharmacological reactions to drinks typically containing 50 mg of theanine per 500 millilitres cannot be excluded, in the opinion of the BfR. Such reactions could include impairment of psychomotor
skills and amplification of the sedating effects of alcohol and hypnotics.
In 2006, a study found no consistent, statistically significant treatment-related adverse effects on behavior, morbidity, mortality, body weight, food consumption and efficiency, clinical chemistry, hematology
, or urinalysis
in rats fed high doses of theanine for 13 weeks. Large studies in humans have not been undertaken.
Amino acid
Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...
and a glutamic acid
Glutamic acid
Glutamic acid is one of the 20 proteinogenic amino acids, and its codons are GAA and GAG. It is a non-essential amino acid. The carboxylate anions and salts of glutamic acid are known as glutamates...
analog commonly found in tea
Tea
Tea is an aromatic beverage prepared by adding cured leaves of the Camellia sinensis plant to hot water. The term also refers to the plant itself. After water, tea is the most widely consumed beverage in the world...
(infusions of Camellia sinensis
Camellia sinensis
Camellia sinensis is the species of plant whose leaves and leaf buds are used to produce Chinese tea. It is of the genus Camellia , a genus of flowering plants in the family Theaceae. White tea, green tea, oolong, pu-erh tea and black tea are all harvested from this species, but are processed...
), primarily in green tea
Green tea
Green tea is made solely from the leaves of Camellia sinensis that have undergone minimal oxidation during processing. Green tea originates from China and has become associated with many cultures throughout Asia. It has recently become more widespread in the West, where black tea is traditionally...
, and also in the basidiomycete mushroom Boletus badius
Boletus badius
Boletus badius , and commonly known as the Bay Bolete is an edible, pored mushroom from Europe and North America...
and in guayusa
Ilex guayusa
Ilex guayusa is an Amazonian tree of the holly genus, native to the Ecuadorian Amazon Rainforest. One of three known caffeinated holly trees, the leaves of the guayusa tree are dried and brewed like a tea for their stimulative effects....
. More specifically, this compound is called L-theanine, being the levorotary enantiomer
Enantiomer
In chemistry, an enantiomer is one of two stereoisomers that are mirror images of each other that are non-superposable , much as one's left and right hands are the same except for opposite orientation. It can be clearly understood if you try to place your hands one over the other without...
. In 1950, the tea laboratory of Kyoto successfully separated theanine from gyokuro
Gyokuro
Gyokuro is a fine and expensive type of green tea from Japan. It differs from the standard green tea known as sencha , because it is grown under the shade rather than the full sun. Another Japanese green tea that is shaded during growth is kabusecha , which differs from gyokuro in the length of...
leaf, which has high theanine content. Theanine is an analog to glutamine
Glutamine
Glutamine is one of the 20 amino acids encoded by the standard genetic code. It is not recognized as an essential amino acid but may become conditionally essential in certain situations, including intensive athletic training or certain gastrointestinal disorders...
and glutamate, and can cross the blood-brain barrier
Blood-brain barrier
The blood–brain barrier is a separation of circulating blood and the brain extracellular fluid in the central nervous system . It occurs along all capillaries and consists of tight junctions around the capillaries that do not exist in normal circulation. Endothelial cells restrict the diffusion...
. It is sold in the US as a dietary supplement, and is FDA confirmed as Generally recognized as safe
Generally recognized as safe
Generally recognized as safe is an American Food and Drug Administration designation that a chemical or substance added to food is considered safe by experts, and so is exempted from the usual Federal Food, Drug, and Cosmetic Act food additive tolerance requirements.-History:On January 1, 1958,...
(GRAS). The Japanese Ministry of Health and Welfare approved the use of theanine for universal consumption in 1964.
Effects on the brain
Able to cross the blood-brain barrierBlood-brain barrier
The blood–brain barrier is a separation of circulating blood and the brain extracellular fluid in the central nervous system . It occurs along all capillaries and consists of tight junctions around the capillaries that do not exist in normal circulation. Endothelial cells restrict the diffusion...
, theanine has psychoactive
Psychoactive drug
A psychoactive drug, psychopharmaceutical, or psychotropic is a chemical substance that crosses the blood–brain barrier and acts primarily upon the central nervous system where it affects brain function, resulting in changes in perception, mood, consciousness, cognition, and behavior...
properties. Theanine has been shown to reduce mental and physical stress
Stress (medicine)
Stress is a term in psychology and biology, borrowed from physics and engineering and first used in the biological context in the 1930s, which has in more recent decades become commonly used in popular parlance...
, and improves cognition and mood in a synergistic manner with caffeine
Caffeine
Caffeine is a bitter, white crystalline xanthine alkaloid that acts as a stimulant drug. Caffeine is found in varying quantities in the seeds, leaves, and fruit of some plants, where it acts as a natural pesticide that paralyzes and kills certain insects feeding on the plants...
.
While structurally related to the excitatory neurotransmitter glutamate, theanine only has weak affinity for the glutamate receptor on postsynaptic cells. Rather, its primary effect seems to increase the overall level of the brain inhibitory transmitter GABA
Gabâ
Gabâ or gabaa, for the people in many parts of the Philippines), is the concept of a non-human and non-divine, imminent retribution. A sort of negative karma, it is generally seen as an evil effect on a person because of their wrongdoings or transgressions...
. Theanine also increases brain dopamine
Dopamine
Dopamine is a catecholamine neurotransmitter present in a wide variety of animals, including both vertebrates and invertebrates. In the brain, this substituted phenethylamine functions as a neurotransmitter, activating the five known types of dopamine receptors—D1, D2, D3, D4, and D5—and their...
levels and has a low affinity for AMPA
AMPA receptor
The α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor is a non-NMDA-type ionotropic transmembrane receptor for glutamate that mediates fast synaptic transmission in the central nervous system . Its name is derived from its ability to be activated by the artificial glutamate analog AMPA...
, kainate
Kainate receptor
Kainate receptors, or KARs, are non-NMDA ionotropic receptors which respond to the neurotransmitter glutamate. They were first identified as a distinct receptor type through their selective activation by the agonist kainate, a drug first isolated from red algae Digenea simplex. KARs are less well...
and NMDA receptor
NMDA receptor
The NMDA receptor , a glutamate receptor, is the predominant molecular device for controlling synaptic plasticity and memory function....
s. Its effect on serotonin
Serotonin
Serotonin or 5-hydroxytryptamine is a monoamine neurotransmitter. Biochemically derived from tryptophan, serotonin is primarily found in the gastrointestinal tract, platelets, and in the central nervous system of animals including humans...
is still a matter of debate in the scientific community, with studies showing increases and decreases in brain serotonin levels using similar experimental protocols. It has also been found that injecting spontaneously hypertensive mice with theanine significantly lowered levels of 5-hydroxyindoles in the brain. Researchers also speculate it may inhibit glutamic acid
Glutamic acid
Glutamic acid is one of the 20 proteinogenic amino acids, and its codons are GAA and GAG. It is a non-essential amino acid. The carboxylate anions and salts of glutamic acid are known as glutamates...
excitotoxicity
Excitotoxicity
Excitotoxicity is the pathological process by which nerve cells are damaged and killed by excessive stimulation by neurotransmitters such as glutamate and similar substances. This occurs when receptors for the excitatory neurotransmitter glutamate such as the NMDA receptor and AMPA receptor are...
. Theanine also promotes alpha wave
Alpha wave
Alpha waves are neural oscillations in the frequency range of 8–12 Hz arising from synchronous and coherent electrical activity of thalamic pacemaker cells in humans...
production in the brain.
Studies on test rats have shown even repeated, extremely high doses of theanine cause little to no harmful psychological or physical effects. Theanine showed neuroprotective effects in one rat study.
A placebo-controlled trial has shown adding theanine to ongoing antipsychotic
Antipsychotic
An antipsychotic is a tranquilizing psychiatric medication primarily used to manage psychosis , particularly in schizophrenia and bipolar disorder. A first generation of antipsychotics, known as typical antipsychotics, was discovered in the 1950s...
medication is helpful in reducing some symptoms of schizophrenia
Schizophrenia
Schizophrenia is a mental disorder characterized by a disintegration of thought processes and of emotional responsiveness. It most commonly manifests itself as auditory hallucinations, paranoid or bizarre delusions, or disorganized speech and thinking, and it is accompanied by significant social...
.
Several beverage manufacturers are selling drinks containing theanine and are marketing them as drinks to help people focus and concentrate, while other manufacturers claim relaxing and tranquillizing properties.
L-Theanine has been shown to both reduce the time that it takes a person to fall asleep as well as decrease the number of nighttime awakenings.
Immune system benefits
L-Theanine may help the body's immune response to infection by boosting the disease-fighting capacity of gamma delta T cells. The study, published in 2003 by the Brigham and Women's HospitalBrigham and Women's Hospital
Brigham and Women's Hospital is the largest hospital of the Longwood Medical and Academic Area in Boston, Massachusetts. It is directly adjacent to Harvard Medical School of which it is the second largest teaching affiliate with 793 beds...
, included a four-week trial with 11 coffee drinkers and 10 tea drinkers, who consumed 600 milliliters of coffee or black tea daily. Blood sample analysis found the production of antibacterial proteins was up to five times higher in the tea drinkers, an indicator of a stronger immune response.
As a supplement
In 2003, the German Federal Institute for Risk Assessment (Bundesinstitut für Risikobewertung, BfR) objected to the addition of isolated theanine to beverages. The institute stated the amount of theanine consumed by regular drinkers of tea or coffee is virtually impossible to determine. While it was estimated the quantity of green teaGreen tea
Green tea is made solely from the leaves of Camellia sinensis that have undergone minimal oxidation during processing. Green tea originates from China and has become associated with many cultures throughout Asia. It has recently become more widespread in the West, where black tea is traditionally...
consumed by the average Japanese tea drinker per day contains about 20 mg of the substance, there are no studies measuring the amount of theanine being extracted by typical preparation methods, or the percentage lost by discarding the first infusion. Therefore, with the Japanese being exposed to possibly much less than 20 mg per day, and Europeans presumably even less, pharmacological reactions to drinks typically containing 50 mg of theanine per 500 millilitres cannot be excluded, in the opinion of the BfR. Such reactions could include impairment of psychomotor
Psychomotor
Psychomotor can refer to:* Psychomotor learning* Psychomotor retardation* Psychomotor agitation...
skills and amplification of the sedating effects of alcohol and hypnotics.
In 2006, a study found no consistent, statistically significant treatment-related adverse effects on behavior, morbidity, mortality, body weight, food consumption and efficiency, clinical chemistry, hematology
Hematology
Hematology, also spelled haematology , is the branch of biology physiology, internal medicine, pathology, clinical laboratory work, and pediatrics that is concerned with the study of blood, the blood-forming organs, and blood diseases...
, or urinalysis
Urinalysis
A urinalysis , also known as Routine and Microscopy , is an array of tests performed on urine, and one of the most common methods of medical diagnosis...
in rats fed high doses of theanine for 13 weeks. Large studies in humans have not been undertaken.
See also
- gamma-GlutamylmethylamideGamma-Glutamylmethylamidegamma-Glutamylmethylamide, also known as GMA, N-methyl-L-glutamine, and metheanine, is an amino acid found in green tea, which is structurally related to L-theanine and L-glutamine....
- Green teaGreen teaGreen tea is made solely from the leaves of Camellia sinensis that have undergone minimal oxidation during processing. Green tea originates from China and has become associated with many cultures throughout Asia. It has recently become more widespread in the West, where black tea is traditionally...