Supplement
Tryptophan is an essential amino acid found in protein foods, which the body uses to build proteins and to make serotonin and melatonin. People mostly look at it for sleep, and the evidence is moderate: trials found people fell asleep sooner, especially those with mild insomnia, and they also rated themselves sleepier. For mood the evidence is limited, with better results than placebo in mild-to-moderate depression but no benefit in severe depression.
- Updated
- How we grade
- Best evidence
- Grade B
- Conditions studied
- 4
- Outcomes
- 6
- Graded outcomes
- 0231
Evidence by condition
- Strong
- Moderate
- Limited
- Very limited
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Sleep Latency Doses ≥1g decrease sleep latency; best results in mild insomnia | Improves (the measure goes down) | Moderate effect | 800 people | |||
| Subjective Sleepiness Increased rated subjective sleepiness at doses ≥1g | Improves (the measure goes up) | Moderate effect | 400 people |
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Depression Symptoms (Mild-Moderate) Better than placebo for mild-moderate depression (Cochrane review) | Improves (the measure goes down) | Moderate effect | 300 people | |||
| Severe Depression Not effective for severe depressive symptoms | Improves (the measure goes down) | Small effect | 150 people |
Seasonal Affective Disorder
- SAD Symptoms: improves
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| SAD Symptoms As effective as light therapy for seasonal affective disorder | Improves (the measure goes down) | Moderate effect | 100 people |
Cognitive Function
- Memory: improves
| Grade | Outcome | Effect | Size | Studies | People | Studies list |
|---|---|---|---|---|---|---|
| Memory Memory improvements mainly in populations with serotonergic disturbances | Improves (the measure goes up) | Small effect | 200 people |
Key findings
- Sleep LatencyImproves (the measure goes down)
- Subjective SleepinessImproves (the measure goes up)
- Depression Symptoms (Mild-Moderate)Improves (the measure goes down)
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Third-party tested Tryptophan products, in the forms the graded studies used where we can match them.
- Grade B
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