Amino Acid
Theanine
Also known as: L-Theanine
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.
Every Theanine product we have scored
| # | Product | Score | Per serving |
|---|---|---|---|
| 1 | Nutricost Caffeine + L-Theanine Capsules | 97 A | $0.53 |
| 2 | Nootropics Depot L-Theanine Capsules | 95 A | $0.18 |
| 3 | Double Wood L-Theanine Supplement | 95 A | $0.17 |
| 4 | Momentous L-Theanine | 95 A | $0.67 |
| 5 | Nutricost L-Theanine Capsules | 95 A | $0.08 |
| 6 | BulkSupplements L-Theanine Powder | 94 A | $0.06 |
| 7 | NOW Foods L-Theanine Pure Powder | 94 A | $0.24 |
| 8 | Transparent Labs Fat Burner | 92 A | $0.92 |
| 9 | Life Extension Enhanced Stress Relief | 91 A | $0.70 |
| 10 | NOW Foods L-Theanine | 91 A | $0.16 |
| 11 | Thorne Theanine | 90 A | $0.76 |
| 12 | Transparent Labs BULK Pre-Workout | 90 A | $1.67 |
Scored on dose accuracy, form, label transparency and third-party testing. Per-serving cost is list price divided by servings per container. No brand pays to be listed or ranked.
Common questions
How much Theanine should I take?
The typical range is 100-400mg. Safe for regular use
When should I take Theanine?
As needed or with caffeine. Either.
Which form of Theanine is best?
Capsule — Common. Other forms in the catalog: Suntheanine, Powder.
Is Theanine safe?
Commonly reported: Very well tolerated. Serious warnings: None. No concerns
Which Theanine supplement scores highest?
Nutricost Caffeine + L-Theanine Capsules, at 97/100. Scored on dose accuracy, form, label transparency and third-party testing — no brand pays to be listed or ranked.
Daily target & upper limit
200 mg / dayTheanine 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
- 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.
Known interactions
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.
- Hidese S, Ogawa S, Ota M, et al. (2017)Acta Neuropsychiatrica
Effects of chronic l-theanine administration in patients with major depressive disorder: an open-label study
- Nobre AC, Rao A, Owen GN (2008)Asia Pacific Journal of Clinical Nutrition
L-theanine, a natural constituent in tea, and its effect on mental state
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.