L-Theanine

L-Theanine is the major amino acid found in Camellia sinensis, the source of green tea. It is an analog of the excitatory neurotransmitter, glutamate, and thusly, binds to glutamate receptors. L-Theanine can antagonize various glutamate receptor subtypes as well as inhibit glutamine and glutamate transporters, which has been shown to be neuroprotective in animal models of focal cerebral ischemia. Further, L-theanine is reported to increase brain levels of dopamine, serotonin, GABA, nerve growth factor, and brain-derived neurotrophic factor.

White Crystalline Solid

ChEBI: L-Theanine is a N(5)-alkylglutamine where the alkyl group is ethyl. It has been isolated from green tea. It has a role as a neuroprotective agent, a plant metabolite and a geroprotector. It is a tautomer of a N(5)-ethyl-L-glutamine zwitterion.

L-Theanine is one of the active ingredients in green tea. It has a variety of physiological functions such as protecting nerves, lowering blood pressure, antioxidant, regulating immune response, improving cognitive ability and calming the mind. Therefore, L-Theanine helps to improve concentration and cognitive ability, improve immune function, reduce stress, relieve anxiety and depression symptoms, and improve sleep. In addition, studies have shown that L-Theanine also helps to alleviate symptoms in patients with high blood pressure and reduces the risk of pancreatic cancer in women.

Amino acid analog of glutamine and component of green tea. Shown to bind to AMPA, Kainate, NMDA and group I mGlu receptors. Displays neuroprotective effects in vivo . Promotes self-renewal of human embryonic stem cells (hESC).

There is some evidence L-theanine supplements may lower blood pressure. If you take one or more medications to lower blood pressure, you may want to avoid taking L-theanine. Due to its relaxing and sleep-supporting effects, L-theanine may also have an additive effect with some sedative medications. Avoid taking supplements containing D-theanine as it may prevent the absorption of L-theanine in the body. 

The tropical and temperate regions of Asian, African, South American countries are considered the main origin of tea plant [C. sinensis or Thea sinensis]. It is a member of Theaceae family. The majority members of Theaceae family are obtained from India, Sri Lanka, China, and Japan. The physiological properties and colour e.g. black, white, green, yellow or oolong tea strongly depends upon the degree of fermentation and processing conditions^[20]. L-theanine is mainly derived from a non-edible mushroom of Xerocomus badius, and C. sinensis. It is an amino acid which accumulates in the leaves of tea like C. sasanqua and C. japonica^[21]. In tea, L-theanine is responsible for a strong smell [aroma]in general and in particular it is linked with tea umami taste^[22]. From the compositional viewpoint, L-theanine comprises approximately 50% of the tea contents. Whereas, the dry tea contains 1-3% of L-theanine only, this higher or lower ratio of L-theanine can vary depending on several factors i.e. cultivation zone, production season, processing techniques, class of tea, time and type of harvest, etc^[27]. Additionally, the harvested tea at the beginning of summer is reported to have more theanine compared with tea harvested in late summer^[27]. Moreover, L-theanine concentration also depends on the type/class of tea. According to one study, a specific type of C. sinensis var. Sinensis has more L-theanine contents as compared to the C. sinensis var. Assamica^[23].