Also known as: tryptophan
Latest evidence update: 2025-11-28
Strongest in Consistency (78). Held back by Recency (34).
Solid mix of RCTs with some methodological gaps.
Good cross-study replication, some imprecision.
Tens of thousands of participants pooled across studies.
Studies agree on direction of effect.
Mostly pre-2020 research; updates may be needed.
No per-outcome numbers yet for this one. Each finding's direction and strength is shown in the research below.
Areas where research points to a consistent direction of effect. The strength of evidence is graded; the size of the effect is not quantified.
Recommended: 500mg before bed
ProtocolEngine provides general health information based on published research. This is not medical advice. Consult a healthcare professional before starting any supplement or health protocol.
May help reduce depressive symptoms when used alongside antidepressant medications
May help reduce symptoms of bipolar mania when added to standard psychiatric treatment
Improves sleep quality and reduces nighttime awakenings when combined with melatonin and vitamin B6
May improve emotional processing and mood by reducing negative emotional bias in middle-aged women
Helps lower elevated uric acid levels when combined with glycine, particularly in people with mild hyperuricemia