N-Acetyl L-Tyrosine (NALT)

More soluble but likely less effective than plain L-tyrosine for raising plasma tyrosine. Standard L-tyrosine is generally preferred.

A rough internal score reflecting quantity, quality, and consistency of human evidence. Not a clinical recommendation.

Pharmacokinetic data suggests NALT is largely excreted unchanged in urine rather than being efficiently deacetylated to free tyrosine. The improved solubility does not appear to translate into better bioavailability. Most cognitive studies used plain L-tyrosine, not NALT.

• Higher water solubility for mixing convenience
• Same theoretical catecholamine precursor role as L-tyrosine

300–600 mg if used, though plain L-tyrosine at 500–2000 mg is generally preferred.

• Same profile as L-tyrosine
• Headache
• GI discomfort

Same precautions as L-tyrosine. The higher cost relative to L-tyrosine is not justified by the evidence.

Marketing claims of superior bioavailability are not supported by pharmacokinetic data. Plain L-tyrosine is the better-studied and likely more effective form.

• Focus50
• Stress45
• Energy35