amino acid Amino Acids Oral

L-Tyrosine

A conditionally essential amino acid that is a precursor to key neurotransmitters like dopamine and norepinephrine, often studied for cognitive and stress support.

Sci.L-Tyrosine 4-hydroxyphenylalanine n-acetyl l tyrosine tyrosol
2 forms
Oral

About L-Tyrosine

L-Tyrosine is a conditionally essential amino acid that serves as a fundamental biochemical precursor for the synthesis of the catecholamine neurotransmitters dopamine, norepinephrine, and epinephrine, as well as thyroid hormones and melanin. It is synthesized in the body from phenylalanine, but under conditions of physical stress, illness, or high cognitive demand, dietary or supplemental intake may become important. Its role in neurotransmitter synthesis underpins its primary research focus on cognitive function, stress resilience, and mood regulation.

Official resources

Fact sheets from the NIH Office of Dietary Supplements related to this ingredient group.

Dietary Supplement Label Database

Ingredient group data in NutriNav is aligned with the NIH Dietary Supplement Label Database (DSLD).

DSLD group id
251

At a glance

Suggested daily

No established RDA. Typical dietary intake from protein sources is estimated at 500-2000 mg/day. Supplemental doses in research often range from 500-2000 mg, taken acutely before cognitive stressors.

Max safe daily

No established UL. Doses up to 12 grams/day for short periods have been used in research with minimal side effects, but long-term safety data is limited.

Approval status

supplement

Compare All Forms

2 forms

Compare supplement forms of L-Tyrosine by absorption quality and what your body actually gets from each:

High Moderate Low
Form Absorption Steps to absorb Notes Action
L-Tyrosine (Free Form)

Amino acid precursor to key neurotransmitters. Supports cogn...

  • UNII: 42HK56048U
  • CAS: 60-18-4
 — — — View →
N-Acetyl L-Tyrosine (NALT)

Acetylated form of L-Tyrosine for improved absorption. Precu...

  • UNII: N1BQ8136N8
  • CAS: 537-55-3
  • Label category: synthetic
 — — — View →

Also appears on labels as

Additional names seen on supplement labels for forms of this ingredient (beyond the main aliases above).

(S)-Tyrosine, Acetyltyrosine, L-Tyrosine, N-Acetyltyrosine, NALT, Tyrosine

Type: Amino Acids

Building blocks of proteins. Essential amino acids must be obtained from diet, while non-essential can be synthesized by the body.

Absorption: Amino acids are generally well-absorbed. Some forms (like citrulline) are more effective than others (like arginine).

Interactions: Generally safe but high doses can cause digestive issues. Some amino acids can affect neurotransmitter levels.

Watch out for

Possible interactions or cautions — talk to a healthcare provider if unsure.

  • May interact with MAO inhibitors and certain antidepressants.

Potential Benefits

Benefits associated with L-Tyrosine forms:

Mood Support Focus and Alertness Physical Performance Cognitive Function (Under Stress) Cognitive Support Under Stress Cognitive Support Under Acute Stress

And 4 more benefits...

Potential Side Effects

Side effects associated with L-Tyrosine forms:

Gastrointestinal Upset How serious: Mild Headache How serious: Mild Gastrointestinal Discomfort How serious: low Potential Interaction with Thyroid Medication How serious: medium Increased Blood Pressure (Theoretical) How serious: low Insomnia or Restlessness How serious: low

What does the research say?

Research indicates that L-Tyrosine supplementation may enhance cognitive performance and resilience to stress, particularly in situations of high cognitive demand or physical stress.