L-theanine: what it is and how much people take
L-theanine is an amino acid found in tea leaves. Studies have looked at focus, stress and sleep, with small effects so far. Studies have usually used 100 to 400 milligrams a day. It has generally been well tolerated in trials.
General information, not medical advice. Check with a doctor or pharmacist before taking a supplement, especially if you are pregnant or breastfeeding, take any medicine, or are under 18.
How much people take
| What studies looked at | Studies have looked at focus, stress and sleep, with small effects so far. |
|---|---|
| Amounts studies used | 100 to 400 milligrams a day. |
| Official upper limit | None set |
Cautions and interactions
- It has generally been well tolerated in trials.
Dose questions
Quick answers
- What is L-theanine?
- L-theanine is an amino acid found in tea leaves.
- What has L-theanine been studied for?
- Studies have looked at focus, stress and sleep, with small effects so far.
- How much L-theanine do studies use?
- 100 to 400 milligrams a day.
- Is L-theanine safe?
- It has generally been well tolerated in trials.
Sources
- Published review (Frontiers in Nutrition)
https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2026.1922819/full
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