Side-by-side comparison of mechanisms, dosing, interactions, and stacking potential.
| L-Theanine | L-Tyrosine | |
|---|---|---|
| Category | Amino Acids | Amino Acids |
| Standard Dose | 100-200mg daily (or as needed for acute anxiety/focus) | 500-2000mg daily |
| Timing | Flexible: morning for calm focus (stack with caffeine), before stressful events, or evening for relaxation/sleep onset. Onset: 30-60 minutes oral, 15-20 min sublingual. | Morning on empty stomach (competes with other large neutral amino acids for BBB transport). 30-60 min before stressful tasks or exercise. |
| Cycle Duration | ongoing or as needed | As needed or cycle 4-8 weeks on, 2 weeks off |
| Evidence Level | strong_human | strong_human |
L-Theanine (gamma-glutamylethylamide) crosses the blood-brain barrier via the large neutral amino acid transporter. It increases alpha brain wave activity (8-13 Hz, associated with relaxed alertness), enhances GABA, serotonin, and dopamine levels in the brain, and antagonizes glutamate excitotoxicity by blocking glutamate binding at AMPA, kainate, and NMDA receptors. It also increases BDNF and NGF expression, supporting neuroplasticity. The combination of glutamate antagonism and GABA/serotonin enhancement produces anxiolysis without sedation — a 'calm focus' state.
100-200mg daily (or as needed for acute anxiety/focus)
Flexible: morning for calm focus (stack with caffeine), before stressful events, or evening for relaxation/sleep onset. Onset: 30-60 minutes oral, 15-20 min sublingual.
ongoing or as needed
L-Tyrosine is the precursor amino acid for catecholamine neurotransmitter synthesis: tyrosine hydroxylase converts tyrosine to L-DOPA (rate-limiting step), which is then converted to dopamine, norepinephrine, and epinephrine. It is also the precursor for thyroid hormones (iodination of tyrosine residues on thyroglobulin produces T3/T4) and melanin (via tyrosinase). Under conditions of acute stress, catecholamine turnover increases dramatically, depleting brain tyrosine pools. Supplementation provides substrate to maintain catecholamine synthesis during stress, sleep deprivation, cold exposure, and cognitive demand.
500-2000mg daily
Morning on empty stomach (competes with other large neutral amino acids for BBB transport). 30-60 min before stressful tasks or exercise.
As needed or cycle 4-8 weeks on, 2 weeks off
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