Cognitive & Mood Dietary supplement

L-Tyrosine

L-Tyr · Tyrosine

Evidence: Studied in humans. Example dose: finalize with a provider. Not a fact-check stamp.

500-2000 mg – 1,000-2,000mg fasted Oral As needed

L-Tyrosine is a non-essential amino acid synthesized in the body from phenylalanine. It serves as the direct precursor to the catecholamine neurotransmitters dopamine, norepinephrine, and epinephrine, as well as to thyroid hormones (T3, T4) and the skin pigment melanin. While endogenous synthesis is generally adequate, supplementation can boost catecholamine availability under conditions of acute stress, sleep deprivation, or cognitive demand - situations where catecholamine synthesis is rate-limited and tyrosine becomes functionally insufficient.

Quick Start

Route

Oral

Start low

1,000-2,000mg Oral

Frequency

As needed (1-3x daily) under stress

Timing

Anytime

Starting dose. 1,000-2,000mg — Fasted

Take on empty stomach - 30+ minutes before food (especially protein). Effective ~30-60 min after dose. For sleep deprivation or cognitive demand: take 30 min before the demanding task. Don't take with high-protein meals - LNAA competition blocks brain delivery.

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Start here. Every protocol below is ordered lowest-first. Begin at the smallest effective dose, hold about a week to assess tolerance, and step up only if needed.

Tiered Protocols · lowest first

Standard

Dopamine Support Under Stress

500-2000 mg · Oral · As needed

human clinical trial · Deijen et al. 1999 (Brain Res Bull)

Precursor to dopamine and noradrenaline. Best taken fasted.

500-2000 mg

As needed

Conservative start

1,000-2,000mg fasted · Oral · As needed (1-3x daily) under stress

conservative starter

1,000-2,000mg fasted

As needed (1-3x daily) under stress

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How it works

L-Tyrosine is the direct precursor to catecholamines via the rate-limiting enzyme tyrosine hydroxylase (TH). TH converts tyrosine to L-DOPA, which is then converted to dopamine. Dopamine is further converted to norepinephrine (in noradrenergic neurons) and norepinephrine to epinephrine (in adrenal medulla).

Under baseline conditions, TH is fully saturated with tyrosine and supplementation has minimal effect. Under acute stress (cold, sleep deprivation, intense cognitive load), catecholamine synthesis dramatically increases, depleting brain tyrosine pools and making TH activity tyrosine-limited. Supplementation in these conditions restores neurotransmitter availability and preserves cognitive function.

Tyrosine crosses the blood-brain barrier via the LAT1 transporter, competing with other LNAAs (phenylalanine, tryptophan, leucine, isoleucine, valine, methionine). High dietary protein dramatically reduces tyrosine BBB transport - hence the importance of fasted dosing.

Thyroid hormone synthesis: tyrosine residues on thyroglobulin are iodinated to form T3 and T4 in the thyroid gland. Adequate tyrosine is required for thyroid hormone production but supplementation rarely addresses thyroid issues unless intake is severely deficient.

Melanin synthesis: tyrosine is the substrate for tyrosinase, which produces melanin in melanocytes. This is largely cosmetic; supplementation does not meaningfully alter pigmentation.

What to expect

Early

Days 1–7

30-60 min post-dose: acute focus/alertness under stress.

Evidence

HumanModerate

AnimalPresent

In-vitroPresent

Each reference below was re-fetched from its PubMed record, and the quoted sentence was confirmed to appear in that abstract and to support the claim it sits under. Follow any of them to read the source.

Evidence boundary from the checked abstract: The results of this study also suggest that tyrosine is a relatively benign treatment at this dose.

The results of this study also suggest that tyrosine is a relatively benign treatment at this dose.

The effects of tyrosine on cognitive performance during extended wakefulness. Aviation, space, and environmental medicine · 1995 · PMID 7794222

Evidence scope. This entry supports only the exact statement quoted from the live abstract; it does not independently verify OnePin's displayed dose, route, frequency, formulation, population, or broader mechanism.

Claims we could not support

No abstract we checked supports these for this molecule at this route. That is not the same as saying they are false — it marks where the evidence is missing.

Dose/route: 1,000-2,000mg fasted; Oral; As needed (1-3x daily) under stress. No checked live PubMed abstract verified this exact displayed dose, route, and frequency for the same molecule/formulation and relevant population.

Primary safety claim: Mild jitteriness or anxiety at high doses (especially combined with caffeine). No checked live PubMed abstract directly verified this source-JSON safety claim at the displayed formulation, route, and regimen.

Interactions & stacking

Two different questions: what is documented about running these together, and what is documented about drawing them into the same syringe. A good pharmacological partner can still have to be pinned separately.

Documented together

Most nootropicsGenerally compatible with other cognitive support compounds. No direct conflicts with racetams, choline sources, etc.

CaffeineCaffeine increases catecholamine release; tyrosine provides substrate for replacement. Synergistic for sustained focus under stress without crash.

L-TheanineTheanine smooths catecholamine-driven anxiety while tyrosine supports performance. Common cognitive stack.

Vitamin B6 (P5P)B6 is required cofactor for aromatic amino acid decarboxylase (DOPA → dopamine). Supports tyrosine-to-dopamine pathway efficiency.

Keep separate

MAOIs (monoamine oxidase inhibitors)MAOIs prevent catecholamine breakdown. Tyrosine increases catecholamine substrate. Combined risk of hypertensive crisis. Strict avoidance recommended.

Levodopa (Parkinson's medication)Tyrosine and levodopa share LAT1 transporter for BBB transit. Tyrosine can reduce levodopa effectiveness. Discuss with neurologist.

Thyroid medications (theoretical)Tyrosine provides thyroid hormone substrate. In hyperthyroidism, may worsen condition. In hypothyroidism, unlikely to replace medication but not contraindicated.

High-protein meals (timing)Other LNAAs compete with tyrosine for BBB transport. Take fasted - dose effect substantially reduced if combined with protein.

Check any specific pair in the Stack & Interaction Checker, which answers both questions separately. Absence of a documented conflict is not evidence of safety.

Pharmacokinetics

Illustrative plasma concentration · 9 h

Half-life

~2 hours

Plasma. CNS effects persist 4-6 hours.

Peak · Tmax

~30-60 minutes

Oral fasted; ~2 hours with food (significantly reduced effect with food).

Elimination

~6-8 hours

For plasma clearance. Catecholamine substrate effects align with plasma curve.

Bioavailability

~70-90%

Oral fasted. Food (especially protein) reduces effective bioavailability for CNS application by 50%+ via LAT1 competition at BBB.

Duration of action

Acute stress-buffering effect: 4-6 hours per dose. No tissue accumulation - this is an acute, as-needed compound.

Clearance

Hepatic metabolism via tyrosine aminotransferase to fumarate and acetoacetate. Some renal excretion.

Storage. Store at room temperature (20-25C) in a cool, dry place. Powder is hygroscopic - keep tightly sealed. Capsules shelf-stable 2+ years.

Regulatory status

Classified as a dietary supplement in the US - no prescription required. Widely available. No FDA-approved medical indication. Used in PKU (phenylketonuria) management as essential nutrient.

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The guide & community

The complete L-Tyrosine walkthrough, real protocol discussion and coaching live inside the BlessUp community on Skool.

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