Comparison
L-Tyrosine vs L-Tryptophan
L-Tyrosine
Amino acid precursor to dopamine, norepinephrine, and epinephrine. Effective for cognitive performance under stress.
L-Tryptophan
Essential amino acid precursor to serotonin and melatonin. Used for sleep and mood support.
| Field | L-Tyrosine | L-Tryptophan |
|---|---|---|
| Category | amino-acid | amino-acid |
| Dose range | 500–2000mg | 500–2000mg |
| Half-life | 2h | 2h |
| Onset | 60min | – |
| Evidence | EVIDENCEA | EVIDENCEB |
| Safety | ●●●●● | ●●●●● |
| Legal (US) | USOTC | USOTC |
| PubMed refs | 480 | 1700 |
The comparison in plain English
Two precursor amino acids that compete for the same transporter (LAT-1) into the brain. Tyrosine is the precursor for dopamine and norepinephrine, focus, motivation, stress resilience. Tryptophan is the precursor for serotonin and melatonin, mood and sleep.
Bottom line
Take Tyrosine in the morning on an empty stomach, Tryptophan in the evening with carbohydrates. Co-ingesting them is counterproductive because they compete.
Choose L-Tyrosine if
You need acute catecholamine support, cognitive performance under stress, sleep deprivation, demanding work. 500–2000mg AM.
Choose L-Tryptophan if
You need serotonin or sleep support. 500–2000mg evening with carbs to facilitate transport.