Best L-Tryptophan Supplements 2026: Cost per Effective Dose
Top pick for L-Tryptophan: BulkSupplements.com L-Tryptophan Capsules 500 mg — 1000mg L-tryptophan per 2 capsules (1,000 mg), Manufactured in a GMP facility, $0.17/day. Our best-value pick.
All L-Tryptophan Supplements Compared
All 6 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 |
|---|---|---|---|---|---|---|
| BulkSupplements.com L-Tryptophan Capsules 500 mg | BulkSupplements | 1000mg L-tryptophan / 2 capsules (1,000 mg) | $0.17 | Manufactured in a GMP facility | Best Value | Buy |
| Nutricost L-Tryptophan 500 mg (with BioPerine) | Nutricost | 1000mg L-tryptophan / 2 capsules (1,000 mg) | $0.25 | Manufactured in a GMP facility | Buy | |
| NOW Foods L-Tryptophan 1,000 mg Double Strength | NOW Foods | 1000mg L-tryptophan / 1 tablet (1,000 mg) | $0.30 | Manufactured in a GMP facility | Buy | |
| Source Naturals L-Tryptophan 500 mg | Source Naturals | 1000mg L-tryptophan / 2 capsules (1,000 mg) | $0.32 | Manufactured in a GMP facility | Buy | |
| NOW Foods L-Tryptophan 500 mg | NOW Foods | 1000mg L-tryptophan / 2 capsules (1,000 mg) | $0.35 | Manufactured in a GMP facility | Buy | |
| Doctor's Best L-Tryptophan 500 mg | Doctor's Best | 1000mg L-tryptophan / 2 capsules (1,000 mg) | $0.44 | Vegan, Non-GMO, Gluten-Free (label claims) | Buy |
In-Depth L-Tryptophan Guides
Go deeper on l-tryptophan — by goal, by form, and what the evidence actually supports:
Our Picks
Best Value: BulkSupplements.com L-Tryptophan Capsules 500 mg
1000mg L-tryptophan per 2 capsules (1,000 mg). Manufactured in a GMP facility. $0.17/day. 120 servings per container at $19.97.
How We Rank L-Tryptophan Supplements
Every product is evaluated on three criteria:
- Cost per day. Not cost per pill or cost per bottle — what it actually costs per day at the product's labelled serving. Where a category's servings differ in strength we flag it above the table, because cost per day is only comparable when the doses are.
- 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-Tryptophan Choice
Not sure which l-tryptophan supplement is right for you? Use our free tools:
- DNA Supplement Analyzer — upload 23andMe or AncestryDNA data to check for genetic variants affecting l-tryptophan 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-tryptophan? Check if you have the right form and dose.
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