5-HTP

5-HTP is the immediate precursor to serotonin, bypassing the rate-limiting tryptophan hydroxylase step. B-grade evidence for depression and appetite reduction. CRITICAL SAFETY WARNING: Risk of serotonin syndrome when combined with SSRIs, MAOIs, or other serotonergic drugs - this combination can be life-threatening. Should not replace professional treatment for depression. May deplete catecholamines (dopamine, norepinephrine) with long-term use without co-supplementation. Derived from Griffonia simplicifolia seeds.

Quick Answer

What it is

5-HTP is the immediate precursor to serotonin, bypassing the rate-limiting tryptophan hydroxylase step. B-grade evidence for depression and appetite reduction.

Key findings

Grade B: Depression Symptoms (Depression)
Grade B: Appetite (Obesity)
Grade C: Weight (Obesity)

Safety

CRITICAL SAFETY WARNING: Risk of serotonin syndrome when combined with SSRIs, MAOIs, or other serotonergic drugs - this combination can be life-threatening.

ℹ️ Quick Facts: 5-HTP

Quick Facts: 5-HTP

Best Evidence:Grade B
Conditions Studied:7
Research Outcomes:11
Grade B Findings:2
Key Effect:Depression

Outcomes by grade:

7 conditions · 11 outcomes

Detailed Outcomes

Grade:

Effect:

Size:

Sort:

Depression Symptoms

Moderate improvement in depression symptoms

133 participants

moderate↓Improves

Appetite

Moderate decrease in appetite

39 participants

moderate↓Improves

Weight

Weight loss secondary to reduced appetite

39 participants

small↓Improves

Appetite

Reduced appetite in diabetics leading to weight loss

25 participants

moderate↓Improves

Weight

25 participants

↑Worsens

Sleep Terror Frequency

Reduced frequency of sleep terrors in children

45 participants

moderate↓Improves

Appetite

Moderate Decrease

20 participants

moderate↓Improves

Weight

20 participants

↑Worsens

Apathy

No effect on apathy in Parkinson's

1 study25 participants

none

Depression Symptoms

25 participants

↑Worsens

Cortisol

48 participants

↑Worsens

Evidence by Condition

Best grade per condition (each condition may have multiple outcomes)

BDepression

1 outcome · 7 studies

↓Depression SymptomsImproves

BObesity

1 outcome · 4 studies

↓AppetiteImproves↓WeightImproves

CType 2 Diabetes

1 outcome · 2 studies

↓AppetiteImproves↑WeightWorsens

CSleep Terrors

1 outcome · 1 study

↓Sleep Terror FrequencyImproves

CWeight Loss & Maintenance

1 outcome · 2 studies

↓AppetiteImproves↑WeightWorsens

DParkinson's Disease

1 outcome · 2 studies

Apathy↑Depression SymptomsWorsens

Research Citations (9)

The effects of oral 5-hydroxytryptophan administration on feeding behavior in obese adult female subjects

J Neural Transm

PMID: 2468734

Eating behavior and adherence to dietary prescriptions in obese adult subjects treated with 5-hydroxytryptophan

Am J Clin Nutr

PMID: 1384305

L -5-Hydroxytryptophan treatment of sleep terrors in children

Eur J Pediatr

PMID: 15146330

Effects of oral 5-hydroxy-tryptophan on energy intake and macronutrient selection in non-insulin dependent diabetic patients

Int J Obes Relat Metab Disord

PMID: 9705024

L-5-hydroxytryptophan induced increase in salivary cortisol in panic disorder patients and healthy volunteers

Psychopharmacology

PMID: 12073163

Effects of 5-hydroxytryptophan on distinct types of depression: a systematic review and meta-analysis.

Nutr Rev

PMID: 31504850

Comparative study of efficacy of l-5-hydroxytryptophan and fluoxetine in patients presenting with first depressive episode.

Asian J Psychiatr

PMID: 23380314

A functional-dimensional approach to depression: serotonin deficiency as a target syndrome in a comparison of 5-hydroxytryptophan and fluvoxamine.

Psychopathology

PMID: 1909444

Efficacy and safety of 5-hydroxytryptophan on depression and apathy in Parkinson's disease: a preliminary finding.

Eur J Neurol

PMID: 32067288

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