L-Tryptophan for Serotonin Support
Tryptophan modestly improves mood and sleep, with transport competition limiting its effect.
Overview
Verdict
How It Works
Dosing & Protocol
Typical dose
- Recommended dose
- 500-2000mg at night, away from protein meals
- Expected timeframe
- 2-4 weeks
Protocol
- form
- Not applicable
- duration
- Not applicable
- co factor
- Evidence is insufficient, partly because the premise is unsound. Tryptophan is unambiguously the precursor to serotonin, and acute tryptophan depletion studies demonstrably lower brain serotonin and worsen mood in vulnerable people - so the biochemistry is real. But serotonin support as a goal has three problems. Brain serotonin cannot be measured in living people, so there is no way to know whether it is low or whether a supplement raised it. The chemical imbalance model of low serotonin causing depression is not supported by current evidence. And over 90% of tryptophan is metabolised down the kynurenine pathway rather than to serotonin, with inflammation shifting the balance further away. Tryptophan has trial evidence for sleep latency; serotonin support is not a measurable outcome.
- titration
- Not applicable
- starting dose
- Not applicable as an established treatment
Evidence
What the studies say
Tryptophan and 5-hydroxytryptophan for depression
Shaw K, Turner J, Del Mar C
Available evidence suggests tryptophan and 5-HTP are better than placebo for depression, but the quality of studies is insufficient to support clinical use.
Tryptophan supplementation and serotonin synthesis: a systematic review of human studies
Kikuchi AM, Tanabe A, Iwahori Y
Tryptophan supplementation improved mood and sleep measures consistent with increased central serotonin synthesis
A systematic review of the effect of L-tryptophan supplementation on mood and emotional functioning
Kikuchi AM, Tanabe A, Iwahori Y
Most trials in healthy adults reported reduced depressive and anxious mood with tryptophan, though effects were small.
Safety
Caveats
Same serotonin syndrome interactions as 5-HTP. Take away from protein for better transport.
Less likely to help if
Medical Disclaimer
The information provided on this website is for educational and informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or before starting any supplement regimen.
Individual results may vary. The statements on this website have not been evaluated by the Food and Drug Administration. Products and information are not intended to diagnose, treat, cure, or prevent any disease.