Amino Acid

Theanine

Also known as: L-Theanine

Evidence

Amino acid from tea promoting calm focus without drowsiness. Alpha brain waves.

Last reviewed June 2026 · Evidence graded from peer-reviewed research, not editorial opinion. Educational only — not medical advice.

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Daily target & upper limit

200 mg / day

Theanine has an established daily reference intake. See best forms, label synonyms, upper-limit warnings, and top-scoring supplements:

Theanine dosage reference →

Primary uses

Anxiety relief
Calm focus
Stress
Sleep quality
Focus
Calm energy
Caffeine synergy

How it works

Increases alpha brain waves
Boosts GABA, serotonin, dopamine
Counteracts caffeine jitters

Dosage

Typical range: 100-400mg
Timing: As needed or with caffeine
With food: Either
Duration: Safe for regular use
Special populations: Caffeine users, daytime anxiety

Forms

Capsule
Suntheanine
Powder

Safety

Common side effects

Very well tolerated

Contraindications

None known

Products containing Theanine

Top-scoring supplements in our catalog that list Theanine on the label. Each product is graded on Formulate's ingredient-level rubric — dose accuracy, form, transparency, and third-party testing.

Nutricost

Caffeine + L-Theanine Capsules

Known interactions

Synergywith l-theanine
L-theanine smooths caffeine's effects

Evidence notes

Strong evidence for stress and anxiety

Grade A: Multiple well-designed human trials support the main claims.

Cited research for Theanine

Clinical studies referenced across Formulate guides that mention theanine. Each links to the full study page with PubMed source + the guides that cite it.

Related in Amino Acid

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Medical disclaimer. This page is educational and does not replace advice from a qualified healthcare provider. Individual needs and risks vary — consult a professional before starting, stopping, or combining supplements, especially if you are pregnant or nursing, taking medication, or managing a health condition.