l-theanine

L-theanine is a non-protein amino acid primarily found in green tea (Camellia sinensis), black tea, and certain mushrooms. It is available as a purified dietary supplement and has been granted generally recognized as safe (GRAS) status by the US FDA[3][7]. L-theanine crosses the blood-brain barrier and exerts neurophysiological effects including anxiolytic (anxiety-reducing) and calming actions through modulation of inhibitory neurotransmitters, selective serotonin and dopamine regulation, increased alpha brain wave activity, antagonism of glutamate receptors, upregulation of GABA levels, antioxidant effects via enhancement of SOD and CAT enzyme activities, anti-inflammatory properties through inhibition of NF-κB signaling pathways, neuroprotection against oxidative stress-induced damage, potential improvement in sleep quality and cognitive function[5][6][8]. Clinical evidence for its use in anxiety reduction or sleep disorders remains limited; most data are from preclinical or small human studies[3][5].

Brand names

Suntheanine

Other names

theanineγ-glutamylethylamidegamma-glutamylethylamide