Theanine

Theanine /ˈθiːəniːn/, commonly known as L-theanine and sometimes L-gamma-glutamylethylamide or N5-ethyl-L-glutamine, is an amino acid analogue of the proteinogenic amino acids L-glutamate and L-glutamine and is found primarily in particular plant and fungal species. It was discovered as a constituent of green tea in 1949 and isolated from gyokuro leaves in 1950, thus rendering it a natural product. It constitutes about 1–2% of the dry weight of green tea leaves. Theanine provides a unique brothy or savory (umami) flavor to green tea infusions.

Not to be confused with threonine, a distinct amino acid, or theine, an archaic synonym of caffeine.
Theanine
L-Theanine
Clinical data
Other namesγ-L-Glutamylethylamide
Dependence
liability		None
Routes of
administration		Oral
Drug classdietary supplement
ATC code
  • none
Legal status
Legal status
  • US: OTC
  • UN: Unscheduled
Pharmacokinetic data
Onset of actionabout 1 hour
Elimination half-lifeCapsule ~1.2 hours
Green Tea ~0.8 hours
Identifiers
  • (2S)-2-Ammonio-5-(ethylamino)-5-oxopentanoate or N-Ethyl-L-glutamine
CAS Number
PubChem CID
DrugBank
ChemSpider
UNII
KEGG
ChEBI
ChEMBL
CompTox Dashboard (EPA)
ECHA InfoCard100.019.436
Chemical and physical data
FormulaC7H14N2O3
Molar mass174.200 g·mol−1
3D model (JSmol)
Melting point174.20 °C (345.56 °F)
Boiling point215 °C (419 °F)
  • CCNC(=O)CC[C@H](N)C(=O)O

  • CCNC(=O)CCC(N)C(O)=O
  • 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) Y
  • Key:DATAGRPVKZEWHA-UHFFFAOYSA-N Y

The name theanine without a prefix generally implies the enantiomer, L-theanine, which is the form found in tea leaves and as a dietary supplement ingredient. The right-handed enantiomer, D-theanine, has been comparatively studied less.

Theanine is sold as a dietary supplement and is considered to be safe at doses up to 250 milligrams (mg) by the US Food and Drug Administration. 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.

Despite this, it is widely consumed in the form of gelatin capsules, tablets, and powder as a mild anxiolytic and sedative. It is often sold in branded supplements with caffeine.

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