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5-HTP and lean mass: grade C

Limited evidence. Direction: No effect.

C LimitedIndustry-fundedShort-term only

Educational guidance, not medical advice

Why this grade

Rubric condition met: One small placebo RCT null on lean mass

In an 8-week placebo-controlled trial in 48 exercise-trained men and women, 100 mg a day of 5-HTP did not significantly change lean body mass measured by bioelectrical impedance. Fat mass fell more than with placebo (p = 0.048), which is not a lean-mass outcome. The trial was small and preliminary, and it was funded by the ingredient supplier NURA, whose CLEANMOOD ingredient was tested.

How we grade evidence

Studies this grade rests on

The Effects of 5-HTP on Body Composition: An 8-Week Preliminary RCT.

Evans C, Mekhail V, Curtis J. The Effects of 5-HTP on Body Composition: An 8-Week Preliminary RCT J Diet Suppl, 2023. PMID 35583055

Result not recorded
Design
Randomized, placebo-controlled trial, 8 weeks (preliminary)
Sample
n = 48
Population
Exercise-trained men and women
Funding
NURA (Crossref funder), the ingredient supplier whose CLEANMOOD 5-HTP ingredient was tested

Search and history

Search (): (5-hydroxytryptophan[ti] OR 5-HTP[ti]) AND (satiety[tiab] OR appetite[tiab] OR weight[tiab] OR body composition[tiab]) AND humans[mh]

  • 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