L-Tyrosine
Also known as: Tyrosine, L-Tyrosine (Thyroid Support), 4-hydroxyphenylalanine
Overview
Precursor to dopamine, norepinephrine, and thyroid hormones. Supports focus and stress resilience.
Frequently Asked About L-Tyrosine
How much L-Tyrosine should I take?
When is the best time to take L-Tyrosine?
Should I take L-Tyrosine with food?
What is the best form of L-Tyrosine?
Does L-Tyrosine interact with medications?
What does L-Tyrosine pair well with?
Who should not take L-Tyrosine?
Compare Forms
3 formsDifferent chemical forms vary in absorption, side effects, and best use cases. Higher bioavailability scores indicate better absorption.
N-Acetyl-L-Tyrosine (NALT)
HIGH 85Acetylated form, often marketed as more bioavailable for cognitive use
💡 Better water solubility. Crosses BBB readily but conversion to free L-tyrosine is partial.
- • Easier to dose at lower amounts
- • Marketed as nootropic-friendly
- • Conversion to active L-tyrosine is incomplete (~30-50%)
- • More expensive
📝 Popular but not necessarily better than plain L-tyrosine for raising tyrosine levels.
Free-form L-Tyrosine
HIGH 100Plain L-tyrosine — what was used in nearly all military / cognitive-stress studies
💡 Excellent. Take on empty stomach, away from other amino acids that compete at BBB.
- • Cheapest
- • Best research evidence
- • Reliable effect at 500-2000 mg
- • Take on empty stomach (away from protein meals) for best effect
📝 Default choice. 500-2000 mg, 30-60 min before stressor or workout. Empty stomach.
DL-Phenylalanine (DLPA, Precursor)
GOOD 75Precursor amino acid that converts to tyrosine in the body
💡 Good. D-phenylalanine inhibits enkephalin breakdown (mood/pain), L-converts to tyrosine.
- • Dual action (mood + tyrosine pathway)
- • Endorphin support unique to D-form
- • Slower than direct tyrosine for cognitive use
- • Avoid if PKU
📝 Better for mood than acute cognitive stress. 500-1500 mg.
Dosage
As needed, cycling may help
High stress, cognitive demands
Research & Studies
We haven’t curated landmark studies for L-Tyrosineyet — one-click into the primary literature here. PubMed (RCTs) is usually the highest-signal starting point.
Mechanism of Action
- • Precursor to L-DOPA then dopamine
- • Supports norepinephrine synthesis
- • Thyroid hormone precursor
Evidence Quality
Supports catecholamine synthesis
Safety & Contraindications
- • Hyperthyroid caution
- • MAOIs
- • Hyperthyroidism
- • Insomnia if taken late
- • Anxiety at high doses
Consult healthcare provider
Safe
Interactions
- • MAOIs contraindicated
- • Thyroid meds
- • Works with B6 for conversion
- • Compete with other amino acids
Stacking & Synergies
Buying Guide
- • L-form
- • Take away from protein meals
- • Morning dosing best
- • Precursor, not hormone itself
- • Empty stomach away from protein
- • Supports both thyroid and dopamine
Top Products with L-Tyrosine
Highest-scored catalog products containing L-Tyrosine, ranked by our scoring engine.
Thyroid Health Complex (formerly Thyrocsin)Thorne94
BULK Pre-WorkoutTransparent Labs91
Emotion Balance SupportThorne90
Amino ComplexThorne87
Related Guides
In-depth guides covering L-Tyrosine — protocols, comparisons, and use cases.
More in Amino Acid
Other ingredients in the Amino Acid category.
Cite this page
Formulate Research Team. (2026, June). L-Tyrosine — Evidence-Based Supplement Guide. Formulate Supplement Encyclopedia. https://app.formulate-health.app/learning/supplements/l-tyrosine
Educational content based on published research and our scoring methodology. Not medical advice — consult a qualified healthcare provider before starting, stopping, or changing supplements, especially if you take medications, are pregnant, or have a medical condition.