Theanine: What is it? What is it for? Why is it used?

(including the well-known matcha tea), but also in the black one.

Shutterstock Theanine - Chemical Structure

Theanine possesses a structure very similar to that of the amino acid glutamine. At the same time, the chemical structure of theanine also has similarities with the structures of gamma-aminobutyric acid (or GABA) and glutamic acid, two very important neurotransmitters of our nervous system.

Theanine is a non-proteinogenic amino acid, which means that unlike glutamine and glutamic acid it is not incorporated into polypeptide chains (proteins).

Where is Theanine found?

As we have said, tea represents the main source of theanine, however, its presence has also been revealed in some plants belonging to the genus Camellia and in some fungi of the species Boletus badius (Xerocomus badius).

and anxiolytic;
  • Adjuvant properties of anticancer chemotherapy;
  • Hypotensive properties, observed only on experimental models;
  • Neuroprotective properties;
  • Immunomodulating properties.
  • What benefits has Theanine shown during the studies?

    Although most of the studies currently published on the clinical and biological efficacy of theanine are experimental in nature, the data obtained are certainly worthy of attention.


    Theanine and relaxation

    The best known and most publicized property of theanine concerns the alleged relaxing, anti-stress and anxiolytic effects. These properties seem to be attributable to the ability of this substance to act as an indirect substrate for the synthesis of GABA (the endogenous precursor of GABA is, in fact, glutamic acid). GABA - also known as gamma-aminobutyric acid - is a neurotransmitter to inhibitory action that promotes the sensation of relaxation Not surprisingly, many drugs with sedative, muscle relaxant, anticonvulsant and hypnotic action, act by stimulating the GABA receptors (in technical terms they are said to be its receptor agonists).

    Rapidly absorbed in the intestine and distributed in the tissues, theanine crosses the blood brain barrier without obstacles, increasing the levels of GABA and consequently recreating the so-called "sense of well-being".

    Its inhibitory or stimulatory effect on the release of serotonin seems less clear, which would be modulated according to the situation; the ability of theanine to favor the release of dopamine appears to be more certain.

    All the above actions would have resulted, in a relatively recent clinical trial, in a clear anxiolytic action, also observed through the "increase in" activity of the alpha brain waves, connected to the general state of rest and sedation.

    Particularly appreciated is the fact that theanine seems to exert its relaxing action without causing drowsiness or altering attention and concentration.

    Theanine and caffeine

    The sedative effect of theanine is able to counteract the excitatory properties of the caffeine present in tea or taken through other foods (guarana, mate, cola, coffee, etc.).
    In fact, caffeine acts as a competitive antagonist of adenosine receptors, increasing the levels of adrenaline and noradrenaline; consequently, it supports the body's metabolism, heart rate, attention threshold, blood pressure and the number of acts. respirators.

    Theanine, glutamic acid and the nervous system

    Recent studies have investigated the ability of theanine to inhibit the "excitatory toxicity" of glutamic acid.
    In fact, in addition to being a precursor of the "relaxing" inhibitory neurotransmitter GABA, glutamic acid as it is, at the level of the nervous system, is an excitatory neurotransmitter.
    Consequently, high concentrations of glutamic acid at the level of the cerebral synapses could favor the appearance of symptoms such as headache, hyper arousal, insomnia, dizziness, palpitations and hot flashes.

    The accumulation of glutamic acid in the brain would also appear to be responsible for the neuronal damage typical of progressive sclerosis (such as amyotrophic lateral sclerosis) and Alzheimer's disease.

    The efficacy of theanine in regulating the levels of glutamic acid in the brain, demonstrated in vitro and on experimental animals, seems to be linked to its modulatory effect at the level of the receptors of this neurotransmitter; in practice, given the structural analogy, theanine it could bind to the glutamic acid receptors stimulating them in a much lower way than the endogenous agonist, or even inhibiting them.

    Theanine and hypertension

    The modulatory activity towards the receptors for glutamic acid would partly justify the central antihypertensive action of theanine. This activity could, therefore, reduce both brain and heart damage related to hypertension.

    Theanine and chemotherapy

    According to research conducted mostly in vitro, theanine could enhance the effect of various anticancer drugs, such as doxorubicin. This synergy would therefore determine:

    • A "more effective antitumor action;
    • Greater success of drug therapy, in particular, in cancers such as ovarian sarcoma and liver metastases;
    • A reduction in the potential side effects of chemotherapy;
    • An improvement in the patient's quality of life.

    However, before a "possible therapeutic application of this type, further studies are needed."

    or as an additive.

    Uses of Theanine in Food Supplements

    Theanine is not a drug and is currently part of the composition of several food supplements used for:

    • Promote relaxation while maintaining attention and concentration;
    • Promote the quality of sleep (in these cases, it is often associated with plant extracts with a sedative and relaxing effect);
    • Balance the stimulating effects of other substances contained in supplements, such as caffeine;
    • Promote attention and concentration.

    Note: within food supplements, theanine is present as L-theanine; in other words, only the L enantiomer is present.

    Did you know that ...

    Theanine is also included in the composition of food supplements for veterinary use whose use is intended for horses, to promote relaxation of the animal.

    Use of Theanine as Food Additives

    Sometimes, theanine is used as an additive to reduce the bitter taste of certain foods. This is possible thanks to the particular taste it possesses.

    . Most of them are formulated in the form of tablets or capsules which are usually swallowed whole with water. But theanine supplements can also be found in the form of oral drops. In any case, for the correct method of taking it is always good to refer to the instructions on the product.

    In what dosage is Theanine taken?

    Indicatively, the dose of theanine usually used is 100-200 mg per day. However, it is very important to respect the dosages indicated on the package and on the package leaflet of the food supplement that you want to take. If in doubt, it is advisable to contact your pharmacist or doctor.


    Furthermore, it should be noted that the use of theanine at the same time as chemotherapy therapy should be strictly supervised by medical personnel and, in any case, must not be carried out without first asking the opinion of one's oncologist or doctor.

    and other hypnotic drugs.

    In any case, other interactions cannot be ruled out; therefore, if you are undergoing drug therapies or are taking other supplements or products of any kind, before taking theanine it is advisable to ask your doctor for advice.

    in sensitive individuals. For this reason, in the event of any unusual effects following the intake of theanine or products containing it, it is advisable to discontinue its use and inform your doctor.


    However, once again the importance of contacting your doctor is reiterated before taking any type of supplement or product containing theanine.

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