L-theanine
An amino acid found in green tea, studied mainly in combination with caffeine: alertness without the jitters.
Benefits
- When combined with caffeine, it improves alertness and attention span over the following two hours (meta-analysis of 11 human trials)
- Reduces anxiety and depressive symptoms at a dose of 200 mg per day over 4 weeks
- Reduces the time it takes to fall asleep and minimises night-time awakenings
- Lowers the heart rate in stressful situations and counteracts the rise in blood pressure caused by caffeine
Precautions
Well tolerated at the doses studied. Caution is advised when taking medication for high blood pressure, as theanine may cause a slight reduction in blood pressure.
Recommended dosage
100 to 200 mg. When taken in combination with caffeine, the most commonly studied ratio is approximately 2:1 (200 mg of theanine to 100 mg of caffeine).
What the studies say
Cette étude a examiné les effets de la L-théanine sur les réponses au stress chez 12 participants. L'ingestion de L-théanine a entraîné une réduction de la fréquence cardiaque et des niveaux d'immunoglobuline A salivaire en réponse à une tâche de stress aigu par rapport à un placebo. Les résultats suggèrent que la L-théanine pourrait avoir des effets anti-stress en inhibant l'excitation neuronale corticale.
Kimura K, Ozeki M, Juneja LR, Ohira H. — Biological psychology (2007) — View the source study
For information only: not a substitute for medical advice. Dietary supplements are not a replacement for a varied, balanced diet. Learn more