Tryptophan

Established role in serotonin synthesis. Supplementation can improve sleep onset and mood in some populations, but 5-HTP is a more direct serotonin precursor.

A rough internal score reflecting quantity, quality, and consistency of human evidence. Not a clinical recommendation.

Tryptophan depletion studies clearly demonstrate its role in serotonin-dependent mood regulation. Supplementation trials show modest improvements in sleep latency and mood, particularly in individuals with lower baseline serotonin status. 5-HTP bypasses the rate-limiting tryptophan hydroxylase step.

• Essential precursor to serotonin and melatonin
• May improve sleep onset latency
• Supports mood in low-serotonin states

Sleep: 500–1000 mg before bed on an empty stomach. Mood: 1–3 g/day in divided doses.

• Drowsiness
• Nausea
• Serotonin syndrome risk with serotonergic drugs

Historical concern from the 1989 eosinophilia-myalgia syndrome outbreak (traced to a contaminated batch, not tryptophan itself). Avoid combining with SSRIs or MAOIs (serotonin syndrome risk).

Competition with other large neutral amino acids for brain uptake means effects depend on the protein context of the diet. 5-HTP may be more efficient for serotonin-specific goals.

• Sleep60
• Mood55
• Anxiety40