L-Theanine
L-theanine · theanine
The green-tea amino acid promoted for calm alertness and better sleep.
TipoSupplement / dietary
Il voto risponde a: What does the human evidence support for: Calm focus & sleep?
Grado
C
Limitata
Il voto misura la qualità dell'evidenza, non è un consiglio ad assumere o acquistare.
- Classe
- Amino acid
- Uso principale
- Calm focus & sleep
- Forza evidenza
- low
- Ultima revisione
- 2026-07-01
In sintesi
A safe, mild relaxant with modest evidence for 'calm focus' — especially paired with caffeine. Not a longevity molecule, but one of the more honest small-benefit supplements.
Cosa dice l'evidenza
L-theanine has small human trials suggesting it reduces subjective stress and, combined with caffeine, improves attention while smoothing caffeine's jitteriness. Some evidence points to better sleep quality (via relaxation rather than sedation). The effects are modest and short-term, and there is no aging or longevity outcome data. Grade C: a legitimate, low-risk 'calm without drowsiness' aid, not a healthspan intervention.
Studi chiave
- [1]
L-theanine and caffeine on attention · RCT
Improved attention and reduced caffeine jitter in combination.
Apri su PubMed ↗ - [2]
L-theanine, stress and sleep · review
Modest reductions in stress; sleep-quality signals.
Apri su PubMed ↗ - [3]
Meccanismo
Crosses the blood-brain barrier and modulates neurotransmitters (increasing GABA, serotonin, dopamine and alpha brain-wave activity), producing relaxation without sedation.
Sicurezza
Very well tolerated; no significant safety concerns at studied doses. Naturally present in tea. May mildly lower blood pressure.
Contesto dosaggio
Trials commonly use ~100–200 mg, often alongside ~100 mg caffeine for the focus effect. A cup of green tea provides much less.
Esempi di applicazione
- Taken ~100–200 mg, often with caffeine for calm focus.
- Also used before bed for relaxation without sedation.
- A gentle, low-risk 'nice to have', not a longevity active.
Nota dal campo
L-theanine is a rare supplement whose modest, honest claim roughly matches its modest, honest evidence. We grade it C and keep it in the 'nice, low-risk, not magic' bucket.