Independent reviews · Updated weekly Editorial & affiliate disclosures
HFL Health Findings Lab™

L-Tyrosine

An amino acid precursor to dopamine and norepinephrine, clinically used to preserve cognitive function and memory under acute physiological or psychological stress.

Evidence-Based
Fact-Checked
Updated: Oct 16, 2026
Share this ingredient:
Clinical Profile

Quick Reference

Scientific Rating
4.6
/ 5.0
Standardized Form
L-Tyrosine or N-Acetyl L-Tyrosine (NALT)

L-Tyrosine is a conditionally essential amino acid that crosses the blood-brain barrier. Once in the brain, it acts as the direct rate-limiting precursor to the catecholamine neurotransmitters: dopamine, norepinephrine, and epinephrine. During periods of acute stress, intense physical exertion, or sleep deprivation, the brain rapidly depletes its catecholamine stores. Supplementing with L-Tyrosine provides the raw material needed to maintain neurotransmitter synthesis, thereby preventing the cognitive decline, brain fog, and mood crashes associated with stress-induced depletion.

Clinical Summary

Supported by robust clinical trials demonstrating its ability to preserve working memory, mental flexibility, and executive function during acute stressors like extreme cold, high altitude, or sleep deprivation.

Dosage Guidelines

500mg to 2,000mg taken 30 to 60 minutes before an acute stressor. Best absorbed on an empty stomach.

Safety & Side Effects

Very safe at standard doses. Extremely high doses may cause mild gastrointestinal upset, headache, or restlessness.

Known Interactions

Contraindicated for individuals taking MAOIs (Monoamine Oxidase Inhibitors) or prescription thyroid hormones (e.g., levothyroxine), as it can dangerously elevate blood pressure or alter thyroid hormone synthesis.

Scientific References

Medical Disclaimer

The information provided in this clinical review is for educational and informational purposes only. It is not intended to be a substitute for professional medical advice, diagnosis, or treatment.

*These statements have not been evaluated by the Food and Drug Administration (FDA). This product or ingredient is not intended to diagnose, treat, cure, or prevent any disease.

Always consult your physician or other qualified health provider with any questions you may have regarding a medical condition, or before beginning any new diet, fitness, supplement, or treatment regimen, especially if you have pre-existing medical conditions or are taking prescribed medications.

Share this ingredient:

Get new reviews in your inbox — weekly, never spammy.

Join our community of readers who use Health Findings Lab to cut through supplement marketing noise.