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Deals

5-HTP and global cognition: grade C

Limited evidence. Direction: No effect.

C LimitedSingle research groupShort-term only

Educational guidance, not medical advice

Why this grade

Rubric condition met: One small single-blinded trial with an untreated control and no placebo, in older adults only; no group-by-time difference

In 30 cognitively healthy older adults, MoCA scores rose within the 5-HTP group over 12 weeks (26.6 to 27.6), but the control group also rose and the group-by-time interaction was not significant (p = 0.9343). Cognition was a secondary outcome, there was no placebo, and the authors ask for cautious interpretation.

How we grade evidence

Studies this grade rests on

The Impact of 5-Hydroxytryptophan Supplementation on Cognitive Function and Mood in Singapore Older Adults: A Randomized Controlled Trial.

Li S, Sutanto CN, Xia X. The Impact of 5-Hydroxytryptophan Supplementation on Cognitive Function and Mood in Singapore Older Adults: A Randomized Controlled Trial Nutrients, 2025. PMID 40944161

Result not recorded
Design
Single-blinded, 12-week parallel randomized controlled trial; control group took nothing (no placebo)
Sample
n = 30
Population
Cognitively healthy older adults in Singapore (66 ± 3 years)
Funding
National University of Singapore iHealthtech Microbiome in Health, Disease and Ageing (PubMed grant)

Search and history

Search (): TITLE:("5-hydroxytryptophan" OR "5-HTP") AND (ABSTRACT:"attention" OR ABSTRACT:"cognitive" OR ABSTRACT:"memory") AND (ABSTRACT:"placebo" OR ABSTRACT:"randomized")

  • Graded C (proposed): Proposed in the monograph draft
  • C to C (approved): Editor sign-off November 13, 2026: grade matches the editor-approved final page