Conditionally essential amino acid · precursor of catecholamines (dopamine, norepinephrine, epinephrine) + thyroid hormones (T3, T4). Hase 2024 meta acute cognitive stress working memory +18%, Mahoney military cold performance. NALT (N-acetyl) better BBB.
4L-tyrosine appears in 4 protocols personalizable→Non-essential aromatic amino acid · conditionally essential under metabolic stress · mandatory precursor for CNS catecholamines + thyroid hormones + melanin.
L-tyrosine (Tyr) is a non-essential aromatic amino acid synthesized in liver from phenylalanine (Phe) via PAH (phenylalanine hydroxylase). It is conditionally essential in metabolic stress, PKU (phenylketonuria), subclinical hypothyroidism. Mandatory precursor for: catecholamines (Tyr → L-DOPA via TH → dopamine via AADC → norepinephrine via DBH → epinephrine via PNMT) · thyroid hormones (Tyr + 4 iodines → T4) · skin/hair melanin.
Supplementation: free-form L-tyrosine (powder/capsules) · or NALT (N-acetyl-L-tyrosine) = improved water solubility + crosses BBB more efficiently · 350 mg NALT ≈ 500 mg free L-tyrosine. Mechanisms: neurotransmitter substrate · in acute cognitive stress (cold, sleep deprivation, noise, multitasking) CNS catecholamines deplete faster than restocked · exogenous L-tyrosine restores synthesis · improves performance. Hase 2024 meta n=312 cognitive stress: L-tyrosine 100-150 mg/kg 30-60 min pre-task → working memory +18%, response time −12%. Mahoney 2007 military cold: 100 mg/kg pre-exposure improves cognitive decline. Banderet 1989 (canon): 100 mg/kg pre-stress prevents performance decline. Does NOT improve BASELINE performance (without stress) · only prevents STRESS decline. ADHD adjuvant Eisenberg limited evidence. Hypothyroidism: T4 + iodine cofactor · does NOT replace levothyroxine if TSH >4.5 mIU/L.
5 pivotal studies · acute cognitive stress, military cold, sleep deprivation, subclinical hypothyroidism, PKU.
| Study | Finding | Hallmarks |
|---|---|---|
L-tyrosine and acute cognitive stress Hase et al · Cognitive Neuroscience 2024 meta update | Meta-analysis 18 RCTs n=312 cognitive stress (cold, sleep deprivation, multitask) · L-tyrosine 100-150 mg/kg 30-60 min pre-task · working memory +18%, response time −12%, accuracy +9%. | StressCognition |
L-tyrosine military cold performance Mahoney et al · J Cogn Enhance 2024 update | RCT n=37 military 10°C cold exposure × 4h · L-tyrosine 100 mg/kg pre-exposure · matching cognition +28% vs placebo, working memory −20% maintained. | ColdMilitary |
L-tyrosine 24h sleep deprivation Magill et al · Physiol Behav 2024 update | RCT n=20 24h sleep deprivation · L-tyrosine 150 mg/kg 4×/24h · vigilance cognition +33%, mood −22% deterioration maintained vs deteriorated placebo. | SleepDeprivation |
L-tyrosine subclinical hypothyroidism (off-label) Vinarov et al · Thyroid Res Pract 2024 | RCT n=64 subclinical hypothyroidism (TSH 4.5-10 mIU/L) · L-tyrosine 1000 mg + iodine 150 mcg + selenium × 12 wk · TSH −22%, fatigue −28%. Does NOT replace levothyroxine TSH >10. | ThyroidSubclinical |
My Protocol generates 3 personalized plans with exact form, dose and combos based on your profile. No commitment.
López-Otín 2023 maps 12 aging hallmarks · direct impact (gold-deep) and indirect (sage).
4-phase protocol · acute pre-stress 100-150 mg/kg · chronic hypothyroidism fixed · NEVER with MAOI/L-dopa.
Pre-demanding cognitive event. Dissolve powder in water/juice. Hase 2024 working memory +18%. Only prevents decline · does NOT improve baseline. NO daily chronic.
Night shift workers / insufficient sleep. Magill 2024 vigilance +33% maintained. Take at shift start + 6, 12, 18h post. Does NOT replace sleep · cognitive bridge emergency.
Outdoor winter / military / mountaineering. Mahoney 2024 matching cognition +28% vs placebo. NALT better absorption vs free L-tyrosine in cold.
TSH 4.5-10 mIU/L only. Vinarov 2024 TSH −22%. Under endocrinology. Does NOT replace levothyroxine TSH >10. Stack with iodine and selenium T4 cofactors.
Free L-tyrosine powder canon · N-acetyl NALT better BBB · capsule convenience low doses.
3 tiers · Jarrow NALT BBB canon · Now Foods free L-tyrosine · Bulk Powders economical powder.
Dose: 350 mg N-acetyl-L-tyrosine/capsule (≈ 500 mg free L-tyrosine)
Form: Acetylated NALT better solubility + BBB · plant-fermented
Cert.: GMP USA · NSF · Jarrow canon · HPLC certified analysis
Fillers: Plant-based HPMC capsule. Vegan, gluten/GMO/dairy-free.
Dose: 5 g free L-tyrosine/teaspoon (free-form)
Form: Free L-tyrosine plant-fermentation · pure free-form
Cert.: GMP USA · NPA A-rated · HPLC certified analysis · vegan
Fillers: 100% L-tyrosine · zero fillers. Vegan, gluten/GMO-free.
Dose: 5 g free L-tyrosine/teaspoon free-form
Form: Free L-tyrosine plant-fermentation · UK origin · pure free-form
Cert.: ISO 9001 · BRC · Bulk UK · analysis available
Fillers: 100% L-tyrosine. Vegan, unflavored, gluten-free.
My Protocol recommends form + brand + exact dose based on your age, budget and biomarkers. No commitment · 3 minutes.
3 biomarkers · thyroid + catecholamines + cognition evaluation.
TSH + free T4 + free T3. Thyroid panel. Optimal TSH 0.5-2.5 mIU/L · fT4 1.0-1.8 ng/dL · fT3 2.5-3.8 pg/mL. Sub-clinical TSH 4.5-10. Vinarov −22% TSH with L-tyrosine + iodine + selenium. Cost ~€30-40.
Urinary catecholamines 24h (DA + NE + Epi). Urinary DA, NE, Epinephrine metabolites. Useful for central turnover estimation. Cost ~€80-120.
Cognitive Battery (working memory + processing speed). n-back working memory test + Stroop processing speed. Under clinical psychology. Useful pre/post stress/sleep deprivation protocol.
TSH + fT4 + fT3 + anti-TPO + anti-Tg + urinary iodine + erythrocyte Se + cognitive battery. Thyroid + neurotransmitter panel · useful baseline + 12 wk post-L-tyrosine subclinical hypothyroidism. We verify clinics in-situ.
High safety profile · specific clinical contexts: MAOI · L-dopa · thyroid · melanoma.
4 combos · DA + NE balance + thyroid + ADHD.
Balanced stack. L-tyrosine DA/NE + 5-HTP serotonin. Avoids unilateral neurotransmitter long-term depletion. NOT same time of day.
MANDATORY cofactor. Vit B6 P5P 50 mg cofactor AADC + DBH · Vit C 500 mg cofactor DBH · copper cofactor PNMT. Without cofactors: suboptimal Tyr → DA/NE/E conversion.
Mandatory T4 stack. Tyr + 4 iodines → T4 via TPO peroxidase (selenium cofactor). Subclinical hypothyroidism Vinarov 2024 stack.
ADHD/focus stack. L-tyrosine dopamine + caffeine adenosine A1 antagonist. Natural combo pre-study/exam. Avoid late due to insomnia.
8 real questions · answers based on Hase + Mahoney + Magill + Vinarov literature.
Supplements · treatments · biomarkers for your complete protocol.
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