N-Acetyl L-Tyrosine (NALT)

Mechanism of action

Hydrolysed to free tyrosine in tissues, which then enters the standard catecholamine synthesis pathway. The acetyl group was intended to improve water solubility and BBB penetration, but pharmacokinetic studies show NALT is converted to free tyrosine with lower efficiency than direct oral tyrosine. Most of the NALT dose is excreted unchanged in urine.

History

N-acetyl-L-tyrosine was developed as a parenteral nutrition formulation because plain L-tyrosine has limited solubility for IV use. The supplement market adopted NALT under the assumption that the same advantages would apply to oral use, which doesn't follow pharmacokinetically. Multiple studies have shown plain L-tyrosine produces higher plasma tyrosine and stronger effects than NALT at equivalent doses.

Benefits

• Catecholamine support (less efficient than L-tyrosine)

  EVIDENCEC

  Pharmacokinetic studies.

• Pre-workout cognitive support in mixed blends

  EVIDENCEC

  Frequently included in pre-workout blends for tyrosine delivery; the bioavailability is real if smaller than plain tyrosine.

Side effects

• Mild GI upsetraremild

Cited research

• NALT pharmacokinetics vs L-tyrosine (Magnusson)1989
  PMID 2768070 ↗
• Acetylated amino acid bioavailability review2004
  PMID 15068944 ↗

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