5-HTP vs L-Tryptophan: Evidence and Safety | Dose Track
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5-HTP vs L-tryptophan: how do the serotonin precursors compare?

How they work · Evidence · EMS history · Safety

Short answer: L-tryptophan is an essential amino acid; the body turns it into 5-HTP and then serotonin.1 A Cochrane review pooled both for depression and found only two usable trials with 64 people, too weak to be conclusive.2 Tryptophan has small sleep data.3 A 1989 outbreak of a serious illness was traced to one maker's tryptophan.4

How do 5-HTP and L-tryptophan compare side by side?

From a Cochrane review, a sleep meta-analysis, a 5-HTP review and the CDC-led EMS investigation.
5-HTPL-tryptophan
What it isThe step between tryptophan and serotonin1An essential amino acid from food1
Depression evidencePooled with tryptophan: 2 trials, 64 people; better than placebo but not conclusive2Same pooled review2
Sleep evidenceNot covered in the sources checkedShorter time awake after first falling asleep, more so at 1 g a day or more; other sleep measures unchanged3
How much reaches the brainDepends on how much is turned into serotonin elsewhere first1Depends on enzymes that also send it down other pathways1
Main safety issueSerotonin syndrome and EMS discussed as risks11989 EMS outbreak tied to one maker4
FDA approvalSupplements are not approved before sale5Same5

Reviewed . Half-life figures are shown only where the value Dose Track uses agrees with the cited source.

What does the evidence show?

Depression: the Cochrane review found 108 trials of 5-HTP or tryptophan, but only two, with 64 patients in total, were good enough to include. They suggested a benefit over placebo, but the reviewers said the evidence was not good enough to be conclusive and that the clinical usefulness is limited because proven antidepressants exist.2

Sleep: a 2022 review of tryptophan pooled 4 of 18 articles. Tryptophan shortened time awake after falling asleep, more so at 1 g a day or more, but did not change other parts of sleep.3

We found no trial that compared 5-HTP directly with tryptophan. These are study protocols, not personalized advice; confirm any dosing with your prescriber.

What are the safety concerns?

  • EMS: in 1989, eosinophilia-myalgia syndrome, a serious inflammatory illness, was linked to tryptophan. In a Minnesota investigation, 29 of 30 patients whose source was known had taken tryptophan from a single maker, compared with 21 of 35 controls, and cases were tied to changes in that maker's manufacturing.4 The Cochrane reviewers said a link between these substances and EMS had not been ruled out.2
  • Serotonin syndrome: a 5-HTP review discusses it as a safety issue.1 Do not combine either with antidepressants or other serotonin-raising drugs without your prescriber.

More detail: the 5-HTP (5-Hydroxytryptophan) and L-Tryptophan guides.

This page summarizes labels and published studies. It is not personalized medical advice; confirm any dose or change with your prescriber.
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Frequently asked questions

Is 5-HTP stronger than L-tryptophan?+
No trial has compared them. The Cochrane review pooled both because there were so few good trials.2
Can I take 5-HTP with an SSRI?+
Not without your prescriber. 5-HTP raises serotonin, and a review discusses serotonin syndrome as a risk.1
Does tryptophan help sleep?+
A small meta-analysis found it shortened time awake after falling asleep, more so at 1 g a day or more, but did not change other sleep measures.3
What happened with tryptophan in 1989?+
An outbreak of eosinophilia-myalgia syndrome was traced mostly to tryptophan from one manufacturer made under changed conditions.4
Can I track these in Dose Track?+
Yes. Log each dose and time, and add mood or sleep notes.

Sources

  1. Turner EH, Loftis JM, Blackwell AD. Serotonin a la carte: supplementation with the serotonin precursor 5-hydroxytryptophan. Pharmacol Ther. 2006;109(3):325-338.
  2. Shaw K, Turner J, Del Mar C. Tryptophan and 5-hydroxytryptophan for depression. Cochrane Database Syst Rev. 2002;(1):CD003198.
  3. Sutanto CN, Loh WW, Kim JE. The impact of tryptophan supplementation on sleep quality: a systematic review, meta-analysis, and meta-regression. Nutr Rev. 2022;80(2):306-316.
  4. Belongia EA, et al. An investigation of the cause of the eosinophilia-myalgia syndrome associated with tryptophan use. N Engl J Med. 1990;323(6):357-365.
  5. FDA. Questions and answers on dietary supplements.

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