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Amino acid

L-Tryptophan · L-Tryptophan

An essential amino acid that serves as a precursor to serotonin and melatonin.

B
Evidence grade
Human RCTs, biomarker outcomes

Short answer

Evidence is moderate for sleep improvement and mood support. Safety profile is good at typical doses.

Product and dose overview

L-Tryptophan (L-Tryptophan) is a amino acid with evidence grade B, meaning it is supported by human RCTs. We track 1 products containing L-Tryptophan. Typical doses range from 1000 to 1000 mg per serving. The top-ranked product scores 7.7 out of 10 on our composite scale (dose, evidence, price, testing, transparency). Prices range up to $45.00 per month.

Evidence grade: B Products in database: 1 Category: Amino acid

Top L-Tryptophan products

ProductBrandDosePrice/mo3rd-party testedScore
SureSleepDoNotAge1000 mg$45.00Yes7.7

Scores are editorial judgments, not a scientific standard. See how we score.

What it is

L-tryptophan is an essential amino acid your body cannot make. It is used to produce serotonin (mood) and melatonin (sleep).

Why people take it

Supplementing tryptophan can increase serotonin and melatonin production, which may improve sleep quality and mood.

Our verdict

Evidence is moderate for sleep improvement and mood support. Safety profile is good at typical doses.

Structure & class

L-tryptophan is the sole precursor to serotonin via tryptophan hydroxylase and aromatic L-amino acid decarboxylase, and subsequently to melatonin via acetylation and methylation.

Mechanism & clinical data

RCTs show modest improvements in sleep latency and quality at 1-2g/day. The serotonin pathway is well-established but effect sizes are small.

Pharmacokinetics

2-7 hours; metabolized via kynurenine and serotonin pathways.

Dose & forms

Trial dose
1000 mg
/ day
Range in trials
500 to 2000 mg
/ day
Common forms
Capsule, Powder

What to watch out for

Should not be combined with SSRIs or MAOIs due to serotonin syndrome risk. Quality matters: cheap forms may contain contaminants.

Where this dose comes from

The trial dose above is our editorial pick from the published human trials for this ingredient. We choose the dose that the best-available studies used on the endpoint most relevant to longevity. The range shows the lowest and highest doses tested in published trials. The landmark studies below are the papers we read to set it. You can click through and check our work.

When new trials publish, our automated sweeps flag them. If a new study materially changes the dose, we update it through editorial review and record the old dose, new dose, and the triggering study in every affected product's recommendation history. The dose is never changed automatically.

Regulatory status

EUPermitted as supplement
USGRAS
UKPermitted
CAPermitted as NHP

Timeline

Regulatory events, evidence grade changes, and key research milestones for L-Tryptophan, most recent first. Studies link to the paper; regulatory entries name and link the responsible authority.

  • 2025-04 Regulatory single source
    EU Court sharpens the bar for botanical health claims
    A Court of Justice of the European Union ruling in April 2025 further tightened the requirements for how botanical ingredients (herbs, plant extracts) can be marketed with health claims in the EU, effectively removing much of the flexibility of the on-hold list.
  • 2024-06 Regulatory confirmed
    EU report identifies 117 supplement substances as potential health risks
    The HoA Working Group on Food Supplements (26 European countries) published its first report evaluating 117 substances used in food supplements. Of these, 65 were assessed as likely novel foods, 6 were already regulated, 34 had insufficient data, and 12 were prioritized for Article 8 restriction under Regulation (EC) No 1925/2006. The 12 priority substances include ashwagandha, curcumin, melatonin, piperine, St. John's wort, coumarin, p-synephrine, maca, holy basil, Melaleuca, black cohosh, and L-tryptophan. The report drew on 1,500 RASFF alerts reviewed between 2017 and mid-2022.
    Source →
  • 2024 Research milestone
    HoA 2024 (BVL/NVWA, EU)
    26-country EU working group prioritized L-tryptophan for Article 8 restriction. Identified as exceeding normal dietary intake levels in supplement form, with potential health risks.
    Source →
  • 2006-12 Regulatory confirmed
    EU Health Claims Regulation adopted
    Regulation (EC) No 1924/2006 laid down harmonised rules for nutrition and health claims made on foods, including supplements. Only claims listed in the EU Register of authorised claims can be used. Rejected botanical claims are held in a separate on-hold list.
    Source →
  • 2005 Research milestone
    Hudson et al. 2005 (Prog Neuropsychopharmacol)
    1g tryptophan improved sleep quality and reduced wake time in adults with insomnia.
    Source →
  • 1997 Regulatory confirmed
    EU introduces the Novel Food Regulation
    Regulation (EC) No 258/97 required any food or food ingredient without a history of consumption in the EU before 15 May 1997 to be authorised before being placed on the market. This is the framework that captures NMN, spermidine as a supplement ingredient, urolithin A, and many other longevity actives.
    Source →

Landmark studies

Found in these products (1)

All products in our catalog that contain L-Tryptophan, ranked by our overall score. Ranking is editorial, never paid.

DoNotAge
SureSleep
Adaptogen
Ingredients listed
4 ingredients listedlargest listed: L-Tryptophan 1,000 mg
Price per serving
$1.50$45.00 · 30 servings
Testing
3rd-party listed · public lab certificate

Elemental vs compound: check label

Status as recorded in the catalog from brand materials; not independently verified by NO1GEVITY.

Score & research context 7.7/10

Editorial score, not proof that this product works. Research-dose calculations are not dosing advice.

100%
of trial dose
$1.73
per research-dose day, not label serving
0Trial dose2×
Catalog price · Confirm current price with donotage.org
Editorial guides

Buying guides and comparisons

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Product shelves
See all in Adaptogen (1)

See L-Tryptophan in context: the mechanism it acts through, the biomarker it moves, the products that dose it, and the trials that tested it.

View L-Tryptophan on the Longevity Map →

Frequently asked questions

What is L-Tryptophan?

L-tryptophan is an essential amino acid your body cannot make. It is used to produce serotonin (mood) and melatonin (sleep).

What dose of L-Tryptophan should I take?

The trial dose in published human studies is 1000 mg per day, with a range of 500 to 2000 mg per day. Always consult a qualified clinician before starting any supplement.

Is L-Tryptophan safe?

Should not be combined with SSRIs or MAOIs due to serotonin syndrome risk. Quality matters: cheap forms may contain contaminants.

What is the best L-Tryptophan supplement?

We track 1 products containing L-Tryptophan. The top-ranked product scores 7.7 out of 10 on our composite scale, which evaluates dose, evidence, price, third-party testing, and transparency. See the comparison table above. Scores are editorial judgments, not a scientific standard.

What is the evidence grade for L-Tryptophan?

L-Tryptophan has evidence grade B, meaning it is supported by human RCTs. Grade A means replicated human RCTs with hard endpoints. Grade B means human RCTs with biomarker outcomes. Grade C means mixed or small human trials. See our evidence grading methodology.

Independently checked

Data verification

Evidence grade
B
Human RCTs, biomarker outcomes
Research dose
1000 mg
Products tracked
1
Updated continuously
Safety signal
Should not be combined with SSRIs or MAOIs due to seroton...

Evidence grades are reviewed when new human RCTs are published. Product counts update automatically as new products are added. Dose ranges reflect published trial data, not brand recommendations. Read how we verify.