Best L-Theanine Supplements (2026) — Ranked by Cost per Effective Dose
Top pick for L-Theanine: NOW Foods L-Theanine 200mg with Inositol (120ct) — 200mg per 1 capsule, $0.22/day. Our best-value pick.
All L-Theanine Supplements Compared
All 3 products sorted by cost per clinically-effective daily dose (lowest first). Dose, certification, and pricing verified against NIH DSLD and manufacturer data.
| Product | Brand | Dose / Serving | Cost / Day | Certification | Pick | Buy |
|---|---|---|---|---|---|---|
| NOW Foods L-Theanine 200mg with Inositol (120ct) | NOW Foods | 200mg / 1 capsule | $0.22 | None | Best Value | Buy |
| Sports Research Suntheanine L-Theanine (200mg, 60ct) | Sports Research | 200mg / 1 softgel | $0.32 | Non-GMO Verified | Budget Pick | Buy |
| Thorne Theanine (200mg, 90ct) | Thorne | 200mg / 1 capsule | $0.36 | NSF Certified for Sport | Quality Pick | Buy |
Our Picks
Best Value: NOW Foods L-Theanine 200mg with Inositol (120ct)
200mg per 1 capsule. $0.22/day. 120 servings per container at $25.99.
Quality Pick: Thorne Theanine (200mg, 90ct)
200mg per 1 capsule. NSF Certified for Sport. $0.36/day. 90 servings per container at $32.00.
Budget Pick: Sports Research Suntheanine L-Theanine (200mg, 60ct)
200mg per 1 softgel. Non-GMO Verified. $0.32/day. 60 servings per container at $18.95.
How We Rank L-Theanine Supplements
Every product is evaluated on three criteria:
- Cost per clinically-effective daily dose. Not cost per pill or cost per bottle. We calculate what it actually costs per day to take the dose used in clinical trials.
- Third-party certification. USP Verified, NSF Certified for Sport, and ConsumerLab Approved indicate independent testing for purity, potency, and contaminants.
- Bioavailable form. We prioritize products using the specific chemical form shown to be most effective in published research.
Rankings are not influenced by affiliate commissions. We earn the same commission regardless of which product you choose. Read our full methodology.
Personalize Your L-Theanine Choice
Not sure which l-theanine supplement is right for you? Use our free tools:
- DNA Supplement Analyzer — upload 23andMe or AncestryDNA data to check for genetic variants affecting l-theanine metabolism. Runs entirely in your browser.
- Lab Results Interpreter — enter your blood test values to get personalized dosing recommendations.
- Supplement Stack Builder — build a complete protocol based on your age, sex, medications, and goals.
- Supplement Audit — already taking l-theanine? Check if you have the right form and dose.