Theanine
L-Theanine | |
| Clinical data | |
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| Other names | γ-L-Glutamylethylamide |
| Dependence liability | None |
| Routes of administration | Oral |
| Drug class | dietary supplement |
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| Pharmacokinetic data | |
| Onset of action | about 1 hour |
| Elimination half-life | Capsule ~1.2 hours Green Tea ~0.8 hours |
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| CompTox Dashboard (EPA) | |
| ECHA InfoCard | 100.019.436 |
| Chemical and physical data | |
| Formula | C7H14N2O3 |
| Molar mass | 174.200 g·mol−1 |
| 3D model (JSmol) | |
| Melting point | 174.20 °C (345.56 °F) |
| Boiling point | 215 °C (419 °F) |
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Theanine /ˈθiːəniːn/, also known as L-theanine, L-gamma-glutamylethylamide, or N5-ethyl-L-glutamine, is a non-proteinogenic amino acid similar to the proteinogenic amino acids L-glutamate 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. It constitutes about 1–2% of the dry weight of green tea leaves.
The name theanine usually refers to the enantiomer L-theanine, which is the form found in tea leaves from which it is extracted as a powder. The right-handed enantiomer, D-theanine, is less-studied.
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. In 1964 Japan approved its unlimited use in all foods (including chocolates, soft drinks, and herb teas) except infant food, while since 2007 it is considered to be safe at doses up to 250 milligrams (mg) per serving by the US Food and Drug Administration.
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.