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L-Tyrosine
Cheap amino-acid precursor to dopamine, norepinephrine, and epinephrine that only works when those neurotransmitters are being burned…
Aliases (8)
Overview
What is L-Tyrosine?
L-tyrosine is a conditionally essential amino acid and the metabolic precursor to dopamine, norepinephrine, and epinephrine. It is used as a stress-buffer and acute cognitive-performance supplement.
Key Benefits
Preserves working memory and reaction time under acute stress (sleep loss, cold, multitasking), supports catecholamine recovery after stimulant or stressor exposure, and provides building blocks for thyroid hormone synthesis.
Mechanism of Action
Crosses the blood-brain barrier via LAT-1 and is hydroxylated by tyrosine hydroxylase to L-DOPA, then decarboxylated to dopamine, beta-hydroxylated to norepinephrine, and methylated to epinephrine — restoring catecholamine pools depleted by stress.
Pharmacokinetics
▸ Mixing & scoop math Powder
- • Mix into 8-16 oz cold water (or sports drink / protein shake). Most powders dissolve in < 30 sec with a brisk stir.
- • If using a shaker, add liquid first, then powder, then shake — minimizes foam and clumps.
- • Hot water is fine for most amino acids and creatine; avoid for heat-sensitive compounds (NAC degrades above ~60 °C).
- • Drink within 5-10 min of mixing — most powders are stable in solution but taste degrades.
Research Indications
The catecholamine pathway in plain English
Your body makes the "go-go-go" neurotransmitters — dopamine (DA), norepinephrine (NE), epinephrine (EPI) — from the amino acid tyrosine. …
Why it (usually) doesn't matter at baseline
Under normal conditions, TH is more-or-less saturated with tyrosine — there is plenty of substrate, and neurons aren't firing fast enough…
Why it matters under stress / sleep dep / cold
When neurons fire at high frequency (acute stress, sustained cognitive demand, hypothermia, sleep loss), several things happen that flip …
LAT-1 / LNAA competition at the blood-brain barrier
Tyrosine is a Large Neutral Amino Acid (LNAA). It crosses the BBB via the LAT-1 transporter, which is a competitive transporter — at phys…
NALT: marketing vs reality
N-Acetyl-L-Tyrosine has an acetyl group bolted onto the amino nitrogen, which makes it more water-soluble. Supplement marketing leans on …
Pharmacokinetics (oral L-tyrosine)
- Onset: Plasma tyrosine begins rising within 30-60 min on empty stomach - Peak: 90-120 min after dosing - Duration: Plasma elevation per…
Research Protocols
Disclaimer: These are commonly discussed research protocols and not medical advice.
Peptide Interactions
Modafinil works partly through DA reuptake inhibition (and broader monoamine + glutamate effects). Tyrosine provides substrate for the catecholamines that mo…
Classic stress-rescue stack. Caffeine = adenosine antagonism + indirect catecholamine release; theanine = sympathetic dampening / alpha-wave promotion; tyros…
Bupropion is a NDRI (NE + DA reuptake inhibitor). Combining with tyrosine is mechanistically additive — more substrate + better preservation of released cate…
Sulbutiamine restores prefrontal-cortex DA function via different mechanism (B1 derivative); the pair has anecdotal asthenia-rescue overlap. Both PRN tier.
Phenylpiracetam has dopaminergic/sympathomimetic activity; tyrosine substrate complements. Used by athletes pre-event in Russian protocols.
P5P is a cofactor for AADC (the enzyme that converts L-DOPA → DA) and for DBH (DA → NE). Adequate B6 status is a quiet prerequisite for tyrosine to actually …
Cofactors for tetrahydrobiopterin (BH4) regeneration. BH4 is required for TH activity. Iron deficiency is a hidden brake on tyrosine→DA conversion. Not a sup…
classical MAOIs (phenelzine, tranylcypromine), Emsam 9-12 mg patch, selegiline >10 mg oral. Hypertensive crisis risk. Hard contraindication.
LNAA competition crowds tyrosine off the LAT-1 transporter. If you're taking tyrosine for cognitive effect, separate from whey/meat by ≥2 hours.
competes hardest at LAT-1. Some users like the "DLPA" (DL-phenylalanine) supplement; combining DLPA + tyrosine in the same dose largely cancels the brain del…
competes at LAT-1 for BBB transport AND at AADC for conversion. Patients on levodopa should not supplement tyrosine.
theoretical-only interaction; no clinical data shows meaningful issue in euthyroid adults, but flag if the user ever ends up on levothyroxine.
Quality Indicators
Single-ingredient, COA-backed
Look for single-ingredient powders from vendors who publish a Certificate of Analysis.
Mixes cleanly
Should dissolve or suspend cleanly in water without large clumps once stirred.
Off taste or smell
Strong rancid, fishy, or chemical odors can indicate oxidation or contamination.
Color or texture change over time
A powder that yellows, clumps, or hardens over time may be hygroscopic and degraded.
What to Expect
- First doseFor stim-class powders: acute effect within 30-60 min.
- Week 1-2For volumizers (creatine, betaine): muscle fullness builds.
- Week 2-4Performance gains plateau into a new baseline.
- OngoingMaintenance dose continuous; cycle off only if specific indication.
Side Effects & Safety 6
Side Effects
- 1Generally very well tolerated
- 2Mild GI upset / nausea (especially on full stomach or at >3 g doses)
- 3Mild headache (tension or vascular flavor) — sometimes attributed to sudden NE elevation
- 4Jaw tension / mild anxiety (catecholamine elevation in users with already-high baseline arousal)
- 5Insomnia if taken too late in the day (catecholamine elevation persists 4-8 hr)
- 6BP elevation in users with pre-existing hypertension — usually small (<5 mm Hg) but real
When to Stop
- Hypertensive episode if combined with non-selective MAO inhibitors (MAOIs) — the cheese-reaction pathway. Tyrosine itself is the parent molecule of the catecholamine pathway; MAOI + high-dose tyrosine = unrestrained accumulation of catecholamines → hypertensive crisis. Hard contraindication with classical MAOIs (phenelzine, tranylcypromine) and with high-dose selegiline (>10 mg oral or 9-12 mg patch). Low-dose selegiline (1-2.5 mg) is theoretically safer due to MAO-B selectivity at that tier, but caution still warranted.
- Theoretical thyroid concern: Tyrosine is a precursor to thyroid hormone (T3/T4 are tyrosine derivatives iodinated at the phenol ring). In hyperthyroid or Graves' patients, theoretically additional substrate could nudge T4 synthesis upward — but in euthyroid adults the iodine-availability and TSH-feedback steps dominate over substrate availability, and clinically meaningful T4/T3 changes from tyrosine supplementation in healthy adults are not documented. In hypothyroid patients on levothyroxine the theoretical concern is opposite (could improve substrate for endogenous T4 if thyroid still functions) but still no controlled data. For the user (no thyroid issue, no levothyroxine), this is a noted-but-minor risk.
- Catecholamine-secreting tumor (pheochromocytoma): absolute contraindication. Patients with pheo should not supplement tyrosine.
- Melanoma: Tyrosine is a melanin precursor; in advanced metastatic melanoma, some clinicians historically restricted dietary tyrosine. Not a concern for healthy adults; flagged for completeness.
- First 1-2 PRN doses: check for headache, jaw tension, BP feel. If present at 2 g, drop to 1 g.
- Pre-training use: monitor whether subjective stress / arousal goes up uncomfortably. Lehr 2014 anger-increase signal is real for some users.
- With future selegiline addition: keep tyrosine to ≤1 g and confirm low-dose selegiline tier (1-2.5 mg) is genuinely MAO-B-selective. Avoid tyrosine entirely if Emsam patch tier (≥9 mg) ever enters the stack.
References
Attipoe et al., 2015, Mil Med — Rapid Evidence Assessment
10 RCTs + 4 CCTs, weak recommendation for tyrosine in cognitive stress
View StudyPomeroy et al., 2024, Stress — VR active-shooter drill
n=80, 2 g L-tyrosine reduced Stroop missed responses without changing stress markers
View StudyDeijen et al., 1999, Brain Res Bull — combat training cadets
2 g/day × 5 days, improved cognitive performance + reduced BP under stress
View StudyNeri et al., 1995 — extended wakefulness
tyrosine partially restored cognition during sleep deprivation
View StudyMagill et al., 2003 — tyrosine vs phentermine vs caffeine vs d-amphetamine
sleep-deprivation comparison
View StudyMahoney et al., 2007 — cold + working memory
150 mg/kg attenuated cold-induced WM decrement
View StudyEglin et al., 2019, J Physiol — older adults cold exposure
improved core temp maintenance during whole-body cooling
View StudyLehr et al., 2014, Psychoneuroendocrinology — anger under severe stress
counter-signal: tyrosine increased anger in high-severity stress paradigm
View Studyvan de Rest et al., 2017 — older adult dose-response
dose-dependent plasma tyrosine; non-monotonic cognitive effects
View StudyHoffer et al., 2003 — N-acetyl-L-tyrosine bioavailability
IV NALT raised plasma free tyrosine 0-25% vs 130-276% for oral L-tyrosine
View StudyNootropics Depot — L-Tyrosine vs NALT writeup
vendor-side acknowledgment of NALT inferiority
View StudyDaubner et al., 2011, PMC — Tyrosine hydroxylase regulation
TH phosphorylation, BH4 cofactor, rate-limiting role
View StudyFernstrom & Fernstrom — Aromatic amino acids in the brain
LAT-1 / LNAA competition mechanism
View StudyTaylor et al., 2014, Front Psychol — tyrosine + cognitive control + dopamine function
individual differences and dopamine-function dependence
View StudyJongkees et al., 2015, J Psychiatr Res — review of tyrosine in clinical/healthy populations under cognitive demands
narrative review confirming stress-condition pattern
View StudyHow was your experience with this compound?
Anonymous · one vote per session · results below at 5+ votes.
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