Are tryptophan and 5-hydroxytryptophan effective treatments for depression? A meta-analysis

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#5-hydroxytryptophan #depressive-disorder #humans #randomized-controlled-trials-as-topic #treatment-outcome

Are tryptophan and 5-hydroxytryptophan effective treatments for depression? A meta-analysis

Shaw et al., 2002 | Aust N Z J Psychiatry | Meta Analysis

Citation

Shaw Kelly, Turner Jane, Del Mar Christopher. Are tryptophan and 5-hydroxytryptophan effective treatments for depression? A meta-analysis. Aust N Z J Psychiatry. 2002-Aug;36(4):488-91

Abstract

OBJECTIVE: To review the literature regarding the effectiveness of 5-hydroxytryptophan (5-HT) and L-tryptophan in the treatment of unipolar depression. METHODS: A systematic review of the literature from 1966 to 2000 using the search terms 'tryptophan', 5-hydroxytryptophan', '5-HTP', '5-HT' and 'depression'. We extracted and grouped data for meta-analysis by pooling odds ratios (OR) and relative risks where possible. RESULTS: One hundred and eight studies were located of which only two studies, one of 5-HT and one of L-tryptophan, with a total of 64 patients met sufficient quality criteria to be included. These studies suggest 5-HT and L-tryptophan are better than placebo at alleviating depression (Peto OR = 4.1, 95% CI = 1.3-13.2). However, the small size of the studies, and the large number of inadmissible, poorly executed studies, casts doubt on the result from potential publication bias, and suggests that they are insufficiently evaluated to assess their effectiveness. CONCLUSION: A large body of evidence was subjected to very basic criteria for assessing reliability and validity, and was found to largely be of insufficient quality to inform clinical practice. More well-designed studies are urgently required to enable an assessment of what may be an effective class of agents.

Key Findings

One hundred and eight studies were located of which only two studies, one of 5-HT and one of L-tryptophan, with a total of 64 patients met sufficient quality criteria to be included. These studies suggest 5-HT and L-tryptophan are better than placebo at alleviating depression (Peto OR = 4.1, 95% CI = 1.3-13.2). However, the small size of the studies, and the large number of inadmissible, poorly executed studies, casts doubt on the result from potential publication bias, and suggests that they ar

Outcomes Measured

  • depression

Population

Field Value
Population See abstract
Sample Size 64
Age Range See abstract
Condition depression

MeSH Terms

  • 5-Hydroxytryptophan
  • Depressive Disorder
  • Humans
  • Randomized Controlled Trials as Topic
  • Treatment Outcome
  • Tryptophan

Evidence Classification

  • Level: Meta Analysis
  • Publication Types: Journal Article, Meta-Analysis, Systematic Review
  • Vertical: 5-htp

Provenance

  • PMID: 12169147
  • DOI: (not available)
  • PMCID: Not in PMC
  • Verified: 2026-04-09 via PubMed E-utilities API

Source extracted via PubMed E-utilities API on 2026-04-09