Theanine

Theanine
	L-Theanine
Clinical data
Other names	γ-L-Glutamylethylamide
Dependence; liability	None
Routes of; administration	Oral
ATC code	none;
Legal status
Legal status	US: OTC; UN: Unscheduled;
Pharmacokinetic data
Onset of action	~1 hour
Elimination half-life	Capsule: ~1.2 hours ; Green Tea: ~0.8 hours
Identifiers
	IUPAC name (2S)-2-Ammonio-5-(ethylamino)-5-oxopentanoate or N-Ethyl-L-glutamine;
CAS Number	3081-61-6 ;
PubChem CID	439378;
DrugBank	DB12444;
ChemSpider	388498 ;
UNII	8021PR16QO;
KEGG	C01047;
ChEBI	CHEBI:17394 ;
ChEMBL	ChEMBL3039113;
CompTox Dashboard (EPA)	DTXSID80184817 ;
ECHA InfoCard	100.019.436
Chemical and physical data
Formula	C7H14N2O3
Molar mass	174.200 g·mol−1
3D model (JSmol)	Interactive image; Interactive image;
Melting point	174.20 °C (345.56 °F)
Boiling point	215 °C (419 °F)
	SMILES CCNC(=O)CC[C@H](N)C(=O)O; ; CCNC(=O)CCC(N)C(O)=O;
	InChI InChI=1S/C7H14N2O3/c1-2-9-6(10)4-3-5(8)7(11)12/h5H,2-4,8H2,1H3,(H,9,10)(H,11,12) ; Key:DATAGRPVKZEWHA-UHFFFAOYSA-N ;

Theanine /ˈθiːəniːn/, also known as L-γ-glutamylethylamide, N⁵-ethyl-L-glutamine, or γ-glutamylethylamide, is a bioactive, non-proteinogenic amino acid similar to the proteinogenic amino acids glutamic acid and L-glutamine. It is produced by certain plants such as the tea plant (Camellia sinensis), and by some fungi. Theanine was discovered in 1949 as a constituent of green tea and was isolated in 1950 from gyokuro tea leaves. Theanine constitutes about 1–2% of the dry weight of green tea leaves.

Theanine is sold as a dietary supplement. It is packaged in gelatin capsules, tablets, and as a powder, and may be an ingredient in branded supplements with caffeine. It is also used as an ingredient in food and beverages. Japan approved its unlimited use in all foods (including chocolates, soft drinks, and herb teas) except infant food in 1964, and the US Food and Drug Administration has considered it to be safe at doses up to 250 milligrams (mg) per serving since 2007.

In 2011, the European Food Safety Authority found there was insufficient evidence for a causal relationship between theanine consumption and improved cognitive function, alleviation of psychological stress, maintenance of normal sleep, or reduction of menstrual discomfort. A 2025 review found that theanine has been poorly studied to date, having inconsistent research quality and unreliable clinical trials.