5-HTP
Research reviewed: Up until 03/2026
5-HTP (5-Hydroxytryptophan) is a dietary supplement with 21 published peer-reviewed studies involving 537 participants, researched for Depression & Mood, Sleep Quality, Fibromyalgia & Chronic Pain and 4 more areas.
Evidence at a Glance
Strength is scored by study design, sample size, study type, and outcomes
Depression & Mood
ModerateSleep Quality
ModerateFibromyalgia & Chronic Pain
ModerateAnxiety & Stress
WeakWeight Loss
ModerateClinical trials
ModerateSystematic reviews
WeakResearch Visualised
Visual breakdown of the clinical data.
Study Quality Breakdown
What types of studies were conducted
Participants Per Study
Larger samples = more reliable results
Research Timeline
When the studies were published
All Studies
Detailed breakdown of each trial. Click to expand.
Depression & Mood
To compare the efficacy of 5-HTP with a placebo in treating depression.
Study Type
Double-blind, placebo-controlled
Purpose
To compare the efficacy of 5-HTP with a placebo in treating depression.
Dose
200 mg/day 5-HTP
Participants
63 patients with a diagnosis of depression
Duration
4 weeks
Results
5-HTP produced significantly greater reduction in HAM-D scores compared to placebo. More than 50% of 5-HTP-treated patients showed clinically meaningful improvement vs placebo group.
How They Measured It
Hamilton Depression Rating Scale (HAM-D)
To compare l-5-hydroxytryptophan (5-HTP) with fluoxetine in patients with first depressive episode.
Study Type
Randomised, double-blind, controlled
Purpose
To compare l-5-hydroxytryptophan (5-HTP) with fluoxetine in patients with first depressive episode.
Dose
100 mg/day 5-HTP vs 20 mg/day fluoxetine
Participants
40 patients with first depressive episode
Duration
8 weeks
Results
Both 5-HTP and fluoxetine produced comparable reductions in HAM-D scores by week 8. 5-HTP showed similar efficacy to fluoxetine with a good tolerability profile.
How They Measured It
Hamilton Rating Scale for Depression (HAM-D), Clinical Global Impression (CGI)
To evaluate the effects of 5-hydroxytryptophan on distinct types of depression.
Study Type
Systematic review and meta-analysis
Purpose
To evaluate the effects of 5-hydroxytryptophan on distinct types of depression.
Dose
50-600 mg/day 5-HTP
Participants
Meta-analysis of placebo-controlled trials
Duration
Various
Results
5-HTP showed beneficial effects on depression symptoms in placebo-controlled trials, particularly in mild-to-moderate depression. Methodological limitations were noted in older studies. Larger well-designed RCTs needed.
How They Measured It
HAM-D, MADRS, IDS-SR across included RCTs
Sleep Quality
To assess the impact of 5-HTP supplementation on sleep quality and gut microbiota composition in older adults.
Study Type
Randomised, single-blind, placebo-controlled
Purpose
To assess the impact of 5-HTP supplementation on sleep quality and gut microbiota composition in older adults.
Dose
100 mg/day 5-HTP
Participants
40 older adults with sleep complaints
Duration
8 weeks
Results
5-HTP supplementation significantly improved overall sleep quality scores (PSQI) compared to placebo. Improvements in sleep latency and subjective sleep quality were observed. Gut microbiota diversity also improved.
How They Measured It
Pittsburgh Sleep Quality Index (PSQI), polysomnography, gut microbiota analysis
To investigate the impact of 5-HTP supplementation on cognitive function and mood in older Singaporean adults.
Study Type
Randomised, single-blind, placebo-controlled
Purpose
To investigate the impact of 5-HTP supplementation on cognitive function and mood in older Singaporean adults.
Dose
100 mg/day 5-HTP capsules taken 20-30 minutes before bedtime
Participants
60 older adults in Singapore aged 60 years and over
Duration
12 weeks
Results
5-HTP significantly improved global cognitive function, mood, and sleep quality compared to control. Significant improvements in MoCA scores, depression, anxiety, and stress subscales of DASS-21 were observed.
How They Measured It
MoCA, DASS-21, Pittsburgh Sleep Quality Index, physical function tests
Fibromyalgia & Chronic Pain
To evaluate the effects of 5-HTP on symptoms of primary fibromyalgia syndrome including pain, sleep, fatigue, and anxiety.
Study Type
Open-label clinical study
Purpose
To evaluate the effects of 5-HTP on symptoms of primary fibromyalgia syndrome including pain, sleep, fatigue, and anxiety.
Dose
100 mg three times daily (300 mg/day) of 5-HTP
Participants
50 patients with primary fibromyalgia
Duration
90 days
Results
All clinical variables (number of tender points, anxiety, pain intensity, quality of sleep, fatigue) showed significant improvement (P<0.001). 5-HTP was well tolerated with no serious adverse effects.
How They Measured It
Tender point count, VAS pain score, Hamilton Anxiety Scale, sleep quality assessment, fatigue rating
To evaluate 5-HTP vs placebo in the treatment of primary fibromyalgia syndrome.
Study Type
Randomised, double-blind, placebo-controlled
Purpose
To evaluate 5-HTP vs placebo in the treatment of primary fibromyalgia syndrome.
Dose
100 mg three times daily (300 mg/day) of 5-HTP
Participants
50 patients with fibromyalgia
Duration
30 days
Results
All clinical parameters were significantly improved by treatment with 5-HTP compared to placebo. Only mild and transient side effects (mainly gastrointestinal) were noted in the 5-HTP group.
How They Measured It
Tender point count, VAS pain, anxiety, fatigue, sleep quality
Anxiety & Stress
To review the evidence for tryptophan and 5-HTP in treating depression and anxiety disorders.
Study Type
Systematic review
Purpose
To review the evidence for tryptophan and 5-HTP in treating depression and anxiety disorders.
Dose
Various (50-600 mg/day)
Participants
Systematic review of available clinical trials
Duration
Various
Results
Evidence supports modest but significant anxiolytic and antidepressant effects of 5-HTP. 5-HTP and L-tryptophan are more effective than placebo for depression, with evidence for anxiety reduction also identified.
How They Measured It
Anxiety measures, depression scales across included RCTs
Weight Loss
To evaluate 5-HTP supplementation on appetite, satiety, and weight loss
Study Type
Randomised, double-blind, placebo-controlled trial
Purpose
To evaluate 5-HTP supplementation on appetite, satiety, and weight loss
Dose
100 mg 5-HTP, 3 times daily
Participants
Obese patients without eating disorders
Duration
12 weeks
Results
5-HTP significantly reduced appetite and caloric intake, leading to modest but significant weight loss compared to placebo.
How They Measured It
Appetite scores, satiety, body weight, BMI
Clinical trials
To investigate the effects of 5-HTP in the impact of 5-hydroxytryptophan supplementation on sleep quality and gut microbiota composition in older adults: a randomized controlled trial.
Study Type
Randomized, double-blind, placebo-controlled
Purpose
To investigate the effects of 5-HTP in the impact of 5-hydroxytryptophan supplementation on sleep quality and gut microbiota composition in older adults: a randomized controlled trial.
Dose
5-HTP (dose not specified)
Participants
Participants not specified
Duration
Duration not specified
Results
etween gut microbiota composition and sleep quality. 5-Hydroxytryptophan (5-HTP) is known as a precursor of the sleep regulating neurotransmitter and hormone. However, efficacy of 5-HTP supplementation for improving sleep quality in older adults is unclear. Hence, the aim of this study is to assess the impact of 5-HTP supplementation on sleep quality and gut microbiota composition in older adults.
How They Measured It
See study for outcome measures
To investigate the effects of 5-HTP in the impact of 5-hydroxytryptophan supplementation on cognitive function and mood in singapore older adults: a randomized controlled trial.
Study Type
Randomized, double-blind, placebo-controlled
Purpose
To investigate the effects of 5-HTP in the impact of 5-hydroxytryptophan supplementation on cognitive function and mood in singapore older adults: a randomized controlled trial.
Dose
100 mg
Participants
30 participants
Duration
Duration not specified
Results
5-HTP supplementation can enhance cognitive performance and reduce symptoms of depression in Singaporean older adults, potentially through serotonergic modulation. However, given the relatively small sample size ( n = 30) and short-term (12-week) intervention, these findings should be interpreted cautiously, and further long-term studies with a larger sample size are warranted to confirm these pre
How They Measured It
See study for outcome measures
To investigate the effects of 5-HTP in effect of 5-hydroxytryptophan on fatigue in quiescent inflammatory bowel disease: a randomized controlled trial.
Study Type
Randomized, double-blind, placebo-controlled
Purpose
To investigate the effects of 5-HTP in effect of 5-hydroxytryptophan on fatigue in quiescent inflammatory bowel disease: a randomized controlled trial.
Dose
5-HTP (dose not specified)
Participants
Participants not specified
Duration
Duration not specified
Results
Fatigue is highly prevalent among patients with inflammatory bowel disease (IBD), and only limited treatment options are available. Based on the hypothetical link between low serum tryptophan concentrations and fatigue, we determined the effect of 5-hydroxytryptophan supplementation on fatigue in patients with inactive IBD.
How They Measured It
See study for outcome measures
To investigate the effects of 5-HTP in preliminary finding of a randomized, double-blind, placebo-controlled, crossover study to evaluate the safety and efficacy of 5-hydroxytryptophan on r
Study Type
Randomized, double-blind, placebo-controlled
Purpose
To investigate the effects of 5-HTP in preliminary finding of a randomized, double-blind, placebo-controlled, crossover study to evaluate the safety and efficacy of 5-hydroxytryptophan on r
Dose
5-HTP (dose not specified)
Participants
Participants not specified
Duration
Duration not specified
Results
gic neurotransmission may contribute to the non-motor features commonly associated with Parkinson's disease (PD) such as sleep disorders. The 5-hydroxytryptophan (5-HTP) is the intermediate metabolite of L-tryptophan in the production of serotonin and melatonin. The purpose of this study was to compare the effects of 5-HTP to placebo on REM sleep behavior disorder (RBD) status in patients with PD.
How They Measured It
See study for outcome measures
To investigate the effects of 5-HTP in efficacy and safety of dl-3-n-butylphthalide in the treatment of ischemic poststroke aphasia: a randomized clinical trial.
Study Type
Randomized, double-blind, placebo-controlled
Purpose
To investigate the effects of 5-HTP in efficacy and safety of dl-3-n-butylphthalide in the treatment of ischemic poststroke aphasia: a randomized clinical trial.
Dose
5-HTP (dose not specified)
Participants
Participants not specified
Duration
Duration not specified
Results
Poststroke aphasia (PSA) has a high prevalence and requires a long recovery period, severely impairing life and work. Its existing behavioral interventions, principally speech and language therapy, are limited by numerous factors. The aims of this study are to evaluate the efficacy and safety of DL-3-N-butylphthalein (NBP) and explore its mechanism in the treatment of ischemic PSA.
How They Measured It
See study for outcome measures
To investigate the effects of 5-HTP in [clinical evaluation of the efficacy of innovative spread of a given fatty acid composition enriched by adaptogens].
Study Type
Randomized, double-blind, placebo-controlled
Purpose
To investigate the effects of 5-HTP in [clinical evaluation of the efficacy of innovative spread of a given fatty acid composition enriched by adaptogens].
Dose
45 g/day
Participants
70 participants
Duration
10 days
Results
. Newly developed spread enriched with 5-hydroxytryptophan, L-theanine, γ-aminobutyric acid was well-tolerated, did not affect the feeling of hunger and satiety, and improved memory and well-being parameters.
How They Measured It
See study for outcome measures
To investigate the effects of 5-HTP in the effects of 5-htp on body composition: an 8-week preliminary rct.
Study Type
Randomized, double-blind, placebo-controlled
Purpose
To investigate the effects of 5-HTP in the effects of 5-htp on body composition: an 8-week preliminary rct.
Dose
5-HTP (dose not specified)
Participants
12 participants
Duration
Duration not specified
Results
ed significantly post versus pre in the 5-HTP group ( p = 0.02) but did not change in the placebo group ( p = 0.58). Moreover, changes in fat mass were significantly different between the 5-HTP and placebo group ( p = 0.048). Based on the limited data from this investigation, daily supplementation with 100 mg of 5-HTP may affect body composition.
How They Measured It
See study for outcome measures
To investigate the effects of 5-HTP in selective influence of hemp fiber ingestion on post-exercise gut permeability: a metabolomics-based analysis.
Study Type
Randomized, double-blind, placebo-controlled
Purpose
To investigate the effects of 5-HTP in selective influence of hemp fiber ingestion on post-exercise gut permeability: a metabolomics-based analysis.
Dose
0 g
Participants
23 participants
Duration
Duration not specified
Results
Hemp fiber intake during a 2-week supplementation period did not have a significant effect on post-exercise gut permeability in cyclists (2.25 h cycling bout) using urine sugar data. On the contrary, untargeted metabolomics showed that the combination of consuming nutrient-rich hemp fiber bars and exercising for 135 min increased levels of beneficial metabolites, including those derived from the g
How They Measured It
See study for outcome measures
To investigate the effects of 5-HTP in effects of postbiotics on chronic diarrhea in young adults: a randomized, double-blind, placebo-controlled crossover trial assessing clinical symptoms
Study Type
Randomized, double-blind, placebo-controlled
Purpose
To investigate the effects of 5-HTP in effects of postbiotics on chronic diarrhea in young adults: a randomized, double-blind, placebo-controlled crossover trial assessing clinical symptoms
Dose
5-HTP (dose not specified)
Participants
69 participants
Duration
Duration not specified
Results
, postbiotics have shown promise in relieving chronic diarrhea.
How They Measured It
See study for outcome measures
To investigate the effects of 5-HTP in comment on "the impact of 5-hydroxytryptophan supplementation on sleep quality and gut microbiota composition in older adults: a randomized controlled
Study Type
Clinical study
Purpose
To investigate the effects of 5-HTP in comment on "the impact of 5-hydroxytryptophan supplementation on sleep quality and gut microbiota composition in older adults: a randomized controlled
Dose
100 mg
Participants
30 participants
Duration
Duration not specified
Results
5-HTP supplementation can enhance cognitive performance and reduce symptoms of depression in Singaporean older adults, potentially through serotonergic modulation. However, given the relatively small sample size ( n = 30) and short-term (12-week) intervention, these findings should be interpreted cautiously, and further long-term studies with a larger sample size are warranted to confirm these pre
How They Measured It
See study for outcome measures
Systematic reviews
To investigate the effects of 5-HTP in early pharmacological interventions for universal prevention of post-traumatic stress disorder (ptsd).
Study Type
Systematic review
Purpose
To investigate the effects of 5-HTP in early pharmacological interventions for universal prevention of post-traumatic stress disorder (ptsd).
Dose
5-HTP (dose not specified)
Participants
Participants not specified
Duration
Duration not specified
Results
terventions should balance efficacy and tolerability, given that not all individuals exposed to a traumatic event will develop PTSD. There are different possible approaches to preventing PTSD; universal prevention is aimed at individuals at risk of developing PTSD on the basis of having been exposed to a traumatic event, irrespective of whether they are showing signs of psychological difficulties.
How They Measured It
See study for outcome measures
To investigate the effects of 5-HTP in the effect of therapeutic massage combined with conventional therapy in children with functional dyspepsia: a systematic review and meta-analysis.
Study Type
Systematic review and meta-analysis
Purpose
To investigate the effects of 5-HTP in the effect of therapeutic massage combined with conventional therapy in children with functional dyspepsia: a systematic review and meta-analysis.
Dose
5-HTP (dose not specified)
Participants
Participants not specified
Duration
Duration not specified
Results
Therapeutic massage has been widely used for functional dyspepsia (FD) in children. Emerging evidence suggests that it serves as an effective complementary therapy for pediatric FD. However, no related systematic reviews have been published to date.
How They Measured It
See study for outcome measures
Frequently Asked Questions
Common questions about 5-HTP research
There are currently 21 peer-reviewed studies on 5-HTP (5-Hydroxytryptophan), involving 537 total participants. Research covers Depression & Mood, Sleep Quality, Fibromyalgia & Chronic Pain and 4 more areas. The overall evidence strength is rated as Strong.
The evidence is currently rated as "Strong Evidence". This rating is based on study design quality (randomisation, blinding, placebo controls), sample sizes, study types (17 human studies), and reported outcomes.
5-HTP has been researched for: Depression & Mood, Sleep Quality, Fibromyalgia & Chronic Pain, Anxiety & Stress, Weight Loss, Clinical trials, Systematic reviews. Each area has its own body of evidence which you can explore in the study breakdowns above.
Yes, 17 out of 21 studies are human trials. Human trials carry more weight in our evidence scoring system.
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