L-Tryptophan

L-tryptophan is a serotonin precursor studied for sleep and mood. Dosing and safety context matter.

Overview

What is L-tryptophan?

L-tryptophan is an essential amino acid that the body uses to make serotonin and niacin (vitamin B3). It is found in many protein-rich foods.

Dosage

A typical dose of L-tryptophan is 500 mg per day.

The typical diet provides around 1-2 grams daily.

Effect graph

Effect heatmap

Possible clinical benefit at 4 stars or greater.


Insomnia	★★★★★	Low
Depression	★★★★★	Low
Seasonal affective disorder (SAD)	★★★★★	Low
Premenstrual dysphoric disorder (PMDD)	★★★★★	Low
Helicobacter pylori (H. pylori)	★★★★★	Low
Gout	★★★★★	Low
Fibromyalgia	★★★★★	Low
Athletic performance	★★★★★	Low
Migraine	★★★★★	Low
Myofascial pain syndrome	★★★★★	Very Low / None
Cognitive impairment	★★★★★	Very Low / None
Bruxism	★★★★★	Very Low / None

Weakest

Strongest

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SupplementDEX Database

12 conditions for and rated at least stars. All purchase bands. No minimum star filter.

Athletic performanceView condition →

Athletic performance

Reconsider purchase★★★★★

How we scored this

Effect SizeLowEvidenceLowTrustMedium

Some studies show that taking L-tryptophan (about 300 mg twice a day) before exercise can boost power output in the final part of exercise by around 5% without making you feel more tired.

Evidence Review

Some studies show that taking L-tryptophan (about 300 mg twice a day) before exercise can boost power output in the final part of exercise by around 5% without making you feel more tired.
However, other research found that higher doses taken during exercise did not improve endurance in trained athletes.
L-tryptophan may help some aspects of athletic performance but not all.

Browse 2 studies

RCTL-tryptophan supplementation can decrease fatigue perception during an aerobic exercise with supramaximal intercalated anaerobic bouts in young healthy men2010

In sportsmen performing aerobic exercise with supramaximal intervals, L-tryptophan supplementation reduced fatigue perception during exercise versus placebo.

Effect: Benefit
Population: Men
Avg age: ~21

RCTIngestion of branched-chain amino acids and tryptophan during sustained exercise in man: failure to affect performance1995

An RCT of 10 endurance-trained men found sucrose drinks with tryptophan or BCAA during 70–75% VO2max cycling for ~122 min did not alter time to exhaustion or fatigue mechanisms.

Effect: No Benefit
Dose: 3 g/day
Population: Athletes

BruxismView condition →

Bruxism

Do not purchase★★★★★

How we scored this

Effect SizeVery Low / NoneEvidenceLowTrustMedium

In a very small study, taking a high dose of L-tryptophan (50 mg/kg body weight daily) for 8 days did not reduce teeth grinding at night compared with a placebo.

Evidence Review

In a very small study, taking a high dose of L-tryptophan (50 mg/kg body weight daily) for 8 days did not reduce teeth grinding at night compared with a placebo.
This suggests L-tryptophan alone is unlikely to help with sleep-related teeth grinding.

Browse 1 study

RCTTryptophan supplementation for nocturnal bruxism: report of negative results1991

In 8 nocturnal bruxists, 50 mg/kg L-tryptophan for 8 days did not significantly reduce bruxing activity versus placebo in a crossover trial.

Effect: No Benefit
Duration: 8 days
Dose: 50 mg/kg
Population: Adults

Cognitive impairmentView condition →

Cognitive impairment

Do not purchase★★★★★

How we scored this

Effect SizeVery Low / NoneEvidenceLowTrustMedium

In older adults with mild memory problems, taking a supplement containing L-tryptophan plus omega-3 fatty acids, vitamin E, soy phospholipids, and melatonin every night for 12 weeks led to small improvements in thinking and sense of smell compared to a placebo.

Evidence Review

In older adults with mild memory problems, taking a supplement containing L-tryptophan plus omega-3 fatty acids, vitamin E, soy phospholipids, and melatonin every night for 12 weeks led to small improvements in thinking and sense of smell compared to a placebo.
People who took the supplement improved slightly on a memory test, while those who took placebo got worse.
It is not clear which ingredient is responsible for the benefit.

Browse 1 study

RCTEffects of a diet integration with an oily emulsion of DHA-phospholipids containing melatonin and tryptophan in elderly patients suffering from mild cognitive impairment2012n=11

In 25 elderly adults with MCI, 12 weeks of DHA-phospholipid emulsion with melatonin and tryptophan did not significantly improve cognition versus placebo.

Effect: No Benefit
Duration: 12 weeks
Population: Older adults
Participants: 11
Avg age: ~86±6

DepressionView condition →

Depression

Reconsider purchase★★★★★

How we scored this

Effect SizeLowEvidenceMediumTrustMedium

L-tryptophan is not recommended for treating depression because there is little solid evidence that it works, and it may rarely cause serious side effects like serotonin syndrome.

Evidence Review

L-tryptophan is not recommended for treating depression because there is little solid evidence that it works, and it may rarely cause serious side effects like serotonin syndrome.
Some older studies suggest it could help when taken with certain older antidepressants, but it's not clear if it helps with newer medications.
Taking it together with antidepressants that affect serotonin can be dangerous and result in serotonin syndrome.

Browse 2 studies1 meta-analysis

MetaClinician guidelines for the treatment of psychiatric disorders with nutraceuticals and phytoceuticals: The World Federation of Societies of Biological Psychiatry (WFSBP) and Canadian Network for Mood and Anxiety Treatments (CANMAT) Taskforce2022

WFSBP/CANMAT 2022 guidelines rated acetyl-L-carnitine as not recommended for ADHD based on Grade A evidence from meta-analyses and RCTs.

RCTPotentiation of the antidepressant action of clomipramine by tryptophan1976n=24

In 24 patients with endogenous depression, clomipramine plus tryptophan showed faster mood improvement than clomipramine plus placebo after 12 days.

Effect: Benefit
Duration: 3 weeks
Population: Patients with depressive disorders
Participants: 24

FibromyalgiaView condition →

Fibromyalgia

Reconsider purchase★★★★★

How we scored this

Effect SizeLowEvidenceLowTrustMedium

Early research in women with fibromyalgia shows that adding small amounts of L-tryptophan and magnesium to a Mediterranean diet for about 4 months helps reduce anxiety, mood problems, eating issues, and dissatisfaction with body image.

Evidence Review

Early research in women with fibromyalgia shows that adding small amounts of L-tryptophan and magnesium to a Mediterranean diet for about 4 months helps reduce anxiety, mood problems, eating issues, and dissatisfaction with body image.
However, it does not appear to improve sleep.
It's not known if the effects come from tryptophan, magnesium, or both together.

Browse 1 study

RCTPsychological and Sleep Effects of Tryptophan and Magnesium-Enriched Mediterranean Diet in Women with Fibromyalgia2020n=22

In 22 women with fibromyalgia, a tryptophan and magnesium-enriched Mediterranean diet improved psychological symptoms and sleep versus control diet.

Effect: Benefit
Duration: 16 weeks
Population: Women
Participants: 22
Avg age: 49±5

GoutView condition →

Gout

Reconsider purchase★★★★★

How we scored this

Effect SizeLowEvidenceLowTrustMedium

Early clinical studies show that taking a powder containing small amounts of L-tryptophan (0.2 g) and glycine (3 g) each night for 6 weeks can lower blood uric acid levels by a small amount.

Evidence Review

Early clinical studies show that taking a powder containing small amounts of L-tryptophan (0.2 g) and glycine (3 g) each night for 6 weeks can lower blood uric acid levels by a small amount.
This includes people with uric acid levels high enough to risk gout.
It's not clear if tryptophan, glycine, or both together cause this benefit.

Browse 1 study

RCTSerum Uric Acid-Lowering Effects of Combined Glycine and Tryptophan Treatments in Subjects with Mild Hyperuricemia: A Randomized, Double-Blind, Placebo-Controlled, Crossover Study2019n=30

In 30 adults with mild hyperuricemia, 6 weeks of 3 g glycine plus 0.2 g tryptophan daily lowered serum uric acid from 7.1 to 6.7 mg/dL versus placebo.

Effect: Benefit
Duration: 6 weeks
Dose: 3.0 g/day
Population: Healthy adults
Participants: 30
Ages: 20–64

Helicobacter pylori (H. pylori)View condition →

Helicobacter pylori (H. pylori)

Reconsider purchase★★★★★

How we scored this

Effect SizeLowEvidenceLowTrustMedium

In people with stomach or duodenal ulcers caused by H.

Evidence Review

In people with stomach or duodenal ulcers caused by H. pylori infection, taking 250 mg of L-tryptophan twice daily along with standard ulcer medicine omeprazole for 3 weeks helped ulcers heal faster than omeprazole alone.
This could be because tryptophan increases certain natural substances in the body that protect and heal the stomach lining.

Browse 1 study

RCTMelatonin or L-tryptophan accelerates healing of gastroduodenal ulcers in patients treated with omeprazole2011n=42

In 42 patients with gastroduodenal ulcers on omeprazole, melatonin or L-tryptophan accelerated ulcer healing versus omeprazole plus placebo over 21 days.

Effect: Benefit
Duration: 21 days
Dose: 20 mg 2×/day
Population: Patients with gastroduodenal ulcers
Participants: 42

InsomniaView condition →

Insomnia

Reconsider purchase★★★★★

How we scored this

Effect SizeLowEvidenceMediumTrustMedium

Small studies suggest that taking L-tryptophan by mouth or through an IV can help people with insomnia fall asleep faster.

Evidence Review

Small studies suggest that taking L-tryptophan by mouth or through an IV can help people with insomnia fall asleep faster.
For example, 500 mg twice a day for 2 weeks helped those detoxing from certain drugs sleep better, though it didn't improve mood.
Taking 1 gram before bedtime may help decrease the time it takes to fall asleep and improve mood, but smaller doses don't seem to help.
A one-time IV dose of 5 grams also helped people fall asleep faster and sleep longer.

Browse 3 studies

RCTTryptophan for the sleeping disorder and mental symptom of new-type drug dependence: A randomized, double-blind, placebo-controlled trial2016n=40

In 80 detoxified new-type drug users, 1,000 mg/day tryptophan for 2 weeks improved sleep disorders and mental symptoms versus placebo.

Effect: Benefit
Duration: 2 weeks
Dose: 1000 mg/day
Population: Children/adolescents
Participants: 40
Ages: 18+

Clinical trialSleep-inducing effect of L-tryptophane1986n=10

In 10 patients with sleep disturbance, 5 g L-tryptophan IV reduced sleep latency versus saline placebo on the third night.

Effect: Benefit
Dose: 5 g/day
Population: Patients with sleep disturbance
Participants: 10

Controlled trialSleep induced by L-tryptophan. Effect of dosages within the normal dietary intake1979

In 15 mild insomniacs, 1 g L-tryptophan at bedtime significantly reduced sleep latency versus placebo; lower doses showed similar trends.

Effect: Benefit
Dose: 2 g/day
Population: Adults

MigraineView condition →

Migraine

Reconsider purchase★★★★★

How we scored this

Effect SizeLowEvidenceLowTrustLow

Early research shows that people who consume about 0.8 to 1 gram of L-tryptophan per day may be about half as likely to have migraines compared to those who consume less than 0.6 grams per day.

Evidence Review

Early research shows that people who consume about 0.8 to 1 gram of L-tryptophan per day may be about half as likely to have migraines compared to those who consume less than 0.6 grams per day.
This suggests eating more tryptophan might help prevent migraines.

Browse 1 study

ObservationalThe association between dietary tryptophan intake and migraine2019n=514

A case-control study of 514 migraineurs versus 582 controls found lower dietary tryptophan intake associated with migraine.

Effect: Benefit
Dose: 0.56 g/day
Population: Healthy adults
Participants: 514

Myofascial pain syndromeView condition →

Myofascial pain syndrome

Do not purchase★★★★★

How we scored this

Effect SizeVery Low / NoneEvidenceLowTrustMedium

In one study, taking 3 grams of L-tryptophan daily along with diet changes did not reduce chronic jaw pain compared to no treatment.

Evidence Review

In one study, taking 3 grams of L-tryptophan daily along with diet changes did not reduce chronic jaw pain compared to no treatment.
Some other studies suggest tryptophan might help with facial pain, but overall the results are inconsistent.

Browse 2 studies

Controlled trialThe effect of L-tryptophan supplementation and dietary instruction on chronic myofascial pain1989

In chronic myofascial pain patients, L-tryptophan supplementation and dietary manipulation did not significantly reduce pain versus control.

Effect: No Benefit
Population: Patients with chronic myofascial pain

RCTThe effects of dietary tryptophan on chronic maxillofacial pain and experimental pain tolerance1982

In 30 chronic maxillofacial pain patients, 3 g/day tryptophan with a high-carbohydrate diet for 4 weeks did not significantly reduce pain versus placebo.

Effect: No Benefit
Duration: 4 weeks
Dose: 3 g/day
Population: Patients with chronic maxillofacial pain

Premenstrual dysphoric disorder (PMDD)View condition →

Premenstrual dysphoric disorder (PMDD)

Reconsider purchase★★★★★

How we scored this

Effect SizeLowEvidenceLowTrustMedium

In a study of women with premenstrual dysphoric disorder (PMDD), taking L‑tryptophan (6 grams per day) from ovulation until the third day of menstruation for three cycles worked better than placebo at easing mood problems like irritability, tension, mood swings, and low mood.

Evidence Review

In a study of women with premenstrual dysphoric disorder (PMDD), taking L‑tryptophan (6 grams per day) from ovulation until the third day of menstruation for three cycles worked better than placebo at easing mood problems like irritability, tension, mood swings, and low mood.
This suggests L‑tryptophan may help by boosting serotonin during the premenstrual phase.

Browse 1 study

RCTA placebo-controlled study of the effects of L-tryptophan in patients with premenstrual dysphoria1999n=37

In 37 women with PMDD, L-tryptophan 6 g/day for 17 days per cycle over 3 cycles significantly reduced dysphoria, mood swings, tension, and irritability versus placebo.

Effect: Benefit
Duration: 17 days
Dose: 6 g/day
Population: Women with PMDD
Participants: 37

Seasonal affective disorder (SAD)View condition →

Seasonal affective disorder (SAD)

Reconsider purchase★★★★★

How we scored this

Effect SizeLowEvidenceLowTrustMedium

A very small study found that taking L‑tryptophan (4–6 grams a day for 4 weeks) seemed to improve seasonal depression about as much as 2 weeks of light therapy.

Evidence Review

A very small study found that taking L‑tryptophan (4–6 grams a day for 4 weeks) seemed to improve seasonal depression about as much as 2 weeks of light therapy.
However, the study was too small to know if there is a real difference between the two approaches.

Browse 1 study

RCTEfficacy of light versus tryptophan therapy in seasonal affective disorder1998n=11

In 13 SAD patients, light therapy for 2 weeks or tryptophan for 4 weeks each improved depression scores, with 31% responding to tryptophan.

Effect: Benefit
Duration: 4 weeks
Population: Patients with depressive disorders
Participants: 11

Database Snapshot

Studies per condition

L-Tryptophan evidence base by condition

Most l-tryptophan research is concentrated in a handful of conditions.

Insomnia accounts for 3 of 17 studies (18%).
Athletic performance accounts for 2 of 17 studies (12%).
Depression accounts for 2 of 17 studies (12%).
Sparse coverage remains for Athletic performance, Depression, Myofascial pain syndrome.

Studies per year

L-Tryptophan publications over time

Dietary Sources

Top dietary sources

Food sources

Sources include Avocados, Bananas, Cheese, Chicken, Eggs, Fish, Milk, Nuts, Seeds, and Spinach.

Safety

Oral L-tryptophan is likely safe when used in doses of up to 5 grams per day for 21 days.

Frequently Asked Questions

References

Sources17 references

SupplementDEX uses only high-quality sources to determine supplement effectiveness.

SupplementDEX Database · Depression

2 references

1.SupplementDEX Database: Depression — Clinician guidelines for the treatment of psychiatric disorders with nutraceuticals and phytoceuticals: The World Federation of Societies of Biological Psychiatry (WFSBP) and Canadian Network for Mood and Anxiety Treatments (CANMAT) Taskforce2022
WFSBP/CANMAT 2022 guidelines rated acetyl-L-carnitine as not recommended for ADHD based on Grade A evidence from meta-analyses and RCTs.
View on PubMed 353116152022
2.SupplementDEX Database: Depression — Potentiation of the antidepressant action of clomipramine by tryptophan1976
In 24 patients with endogenous depression, clomipramine plus tryptophan showed faster mood improvement than clomipramine plus placebo after 12 days.
View on PubMed 9850491976

SupplementDEX Database · Athletic performance

2 references

3.SupplementDEX Database: Athletic performance — L-tryptophan supplementation can decrease fatigue perception during an aerobic exercise with supramaximal intercalated anaerobic bouts in young healthy men2010
In sportsmen performing aerobic exercise with supramaximal intervals, L-tryptophan supplementation reduced fatigue perception during exercise versus placebo.
View on PubMed 204025692010
4.SupplementDEX Database: Athletic performance — Ingestion of branched-chain amino acids and tryptophan during sustained exercise in man: failure to affect performance1995
An RCT of 10 endurance-trained men found sucrose drinks with tryptophan or BCAA during 70–75% VO2max cycling for ~122 min did not alter time to exhaustion or fatigue mechanisms.
View on PubMed 74732391995

SupplementDEX Database · Bruxism

1 reference

5.SupplementDEX Database: Bruxism — Tryptophan supplementation for nocturnal bruxism: report of negative results1991
In 8 nocturnal bruxists, 50 mg/kg L-tryptophan for 8 days did not significantly reduce bruxing activity versus placebo in a crossover trial.
View on PubMed 18121371991

SupplementDEX Database · Cognitive impairment

1 reference

6.SupplementDEX Database: Cognitive impairment — Effects of a diet integration with an oily emulsion of DHA-phospholipids containing melatonin and tryptophan in elderly patients suffering from mild cognitive impairment2012
In 25 elderly adults with MCI, 12 weeks of DHA-phospholipid emulsion with melatonin and tryptophan did not significantly improve cognition versus placebo.
View on PubMed 223340852012

SupplementDEX Database · Fibromyalgia

1 reference

7.SupplementDEX Database: Fibromyalgia — Psychological and Sleep Effects of Tryptophan and Magnesium-Enriched Mediterranean Diet in Women with Fibromyalgia2020
In 22 women with fibromyalgia, a tryptophan and magnesium-enriched Mediterranean diet improved psychological symptoms and sleep versus control diet.
View on PubMed 322249872020

SupplementDEX Database · Gout

1 reference

8.SupplementDEX Database: Gout — Serum Uric Acid-Lowering Effects of Combined Glycine and Tryptophan Treatments in Subjects with Mild Hyperuricemia: A Randomized, Double-Blind, Placebo-Controlled, Crossover Study2019
In 30 adults with mild hyperuricemia, 6 weeks of 3 g glycine plus 0.2 g tryptophan daily lowered serum uric acid from 7.1 to 6.7 mg/dL versus placebo.
View on PubMed 308457312019

SupplementDEX Database · Helicobacter pylori (H. pylori)

1 reference

9.SupplementDEX Database: Helicobacter pylori (H. pylori) — Melatonin or L-tryptophan accelerates healing of gastroduodenal ulcers in patients treated with omeprazole2011
In 42 patients with gastroduodenal ulcers on omeprazole, melatonin or L-tryptophan accelerated ulcer healing versus omeprazole plus placebo over 21 days.
View on PubMed 213620322011

SupplementDEX Database · Insomnia

3 references

10.SupplementDEX Database: Insomnia — Tryptophan for the sleeping disorder and mental symptom of new-type drug dependence: A randomized, double-blind, placebo-controlled trial2016
In 80 detoxified new-type drug users, 1,000 mg/day tryptophan for 2 weeks improved sleep disorders and mental symptoms versus placebo.
View on PubMed 274282012016
11.SupplementDEX Database: Insomnia — Sleep-inducing effect of L-tryptophane1986
In 10 patients with sleep disturbance, 5 g L-tryptophan IV reduced sleep latency versus saline placebo on the third night.
View on PubMed 37581291986
12.SupplementDEX Database: Insomnia — Sleep induced by L-tryptophan. Effect of dosages within the normal dietary intake1979
In 15 mild insomniacs, 1 g L-tryptophan at bedtime significantly reduced sleep latency versus placebo; lower doses showed similar trends.
View on PubMed 4695151979

SupplementDEX Database · Migraine

1 reference

13.SupplementDEX Database: Migraine — The association between dietary tryptophan intake and migraine2019
A case-control study of 514 migraineurs versus 582 controls found lower dietary tryptophan intake associated with migraine.
View on PubMed 312541812019

SupplementDEX Database · Myofascial pain syndrome

2 references

14.SupplementDEX Database: Myofascial pain syndrome — The effect of L-tryptophan supplementation and dietary instruction on chronic myofascial pain1989
In chronic myofascial pain patients, L-tryptophan supplementation and dietary manipulation did not significantly reduce pain versus control.
View on PubMed 27087251989
15.SupplementDEX Database: Myofascial pain syndrome — The effects of dietary tryptophan on chronic maxillofacial pain and experimental pain tolerance1982
In 30 chronic maxillofacial pain patients, 3 g/day tryptophan with a high-carbohydrate diet for 4 weeks did not significantly reduce pain versus placebo.
View on PubMed 67649351982

SupplementDEX Database · Premenstrual dysphoric disorder (PMDD)

1 reference

16.SupplementDEX Database: Premenstrual dysphoric disorder (PMDD) — A placebo-controlled study of the effects of L-tryptophan in patients with premenstrual dysphoria1999
In 37 women with PMDD, L-tryptophan 6 g/day for 17 days per cycle over 3 cycles significantly reduced dysphoria, mood swings, tension, and irritability versus placebo.
View on PubMed 107210421999

SupplementDEX Database · Seasonal affective disorder (SAD)

1 reference

17.SupplementDEX Database: Seasonal affective disorder (SAD) — Efficacy of light versus tryptophan therapy in seasonal affective disorder1998
In 13 SAD patients, light therapy for 2 weeks or tryptophan for 4 weeks each improved depression scores, with 31% responding to tryptophan.
View on PubMed 97162751998

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On this page

Overview Dosage Effect graph Effect heatmap SupplementDEX Database Database Snapshot Dietary Sources Safety Frequently Asked Questions References