Phenylalanine
Phenylalanine
Snapshot
Phenylalanine is an essential aromatic amino acid that serves as a precursor for neurotransmitters and regulates mood, cognition, and protein synthesis.
What is Phenylalanine?
Phenylalanine exists in two forms: L‑phenylalanine (proteinogenic) and D‑phenylalanine. L‑phenylalanine is incorporated into proteins and converted to tyrosine, while D‑phenylalanine exhibits analgesic properties.
Where It Comes From
Dietary sources include meat, fish, eggs, dairy, soy products, nuts, and seeds. Supplemental forms are available as free‑form L‑phenylalanine, DL‑phenylalanine (racemic mix), or as part of amino acid blends.
Key Nutrients & Compounds
L‑phenylalanine provides the substrate for tyrosine and downstream catecholamines (dopamine, norepinephrine, epinephrine). D‑phenylalanine modulates endorphin degradation, supporting pain tolerance.
Health Benefits
Phenylalanine supports neurotransmitter synthesis for mood, focus, and stress response; L‑phenylalanine may improve cognitive performance, while D‑phenylalanine can aid in mild pain relief by inhibiting enkephalinases.
Recommended Dosage
L‑phenylalanine: 500 mg to 1,500 mg daily, often divided; DL‑phenylalanine: 500 mg to 2 g daily, depending on therapeutic goal; adjust under healthcare guidance.
How to Use It
Take on an empty stomach or between meals to optimize uptake; split doses morning and midday to support daytime neurotransmitter production without affecting sleep.
Who Should Use It?
Individuals seeking natural mood and cognitive support, attention enhancement, or adjunctive pain management; avoid if prone to phenylketonuria (PKU) or uncontrolled hypertension.
Possible Interactions or Cautions
Contraindicated in PKU; may raise blood pressure in sensitive individuals; avoid concurrent MAO‑inhibitor use; high doses can cause headache, anxiety, or heart palpitations.
Final Thoughts
Phenylalanine is a versatile amino acid precursor for critical neurotransmitters and endorphin modulation, offering benefits for mood, cognition, and mild pain relief when used judiciously.
Scientific Studies
Fernstrom JD, Wurtman RJ. Brain serotonin content: physiological dependence on plasma tryptophan levels. Science. 1972;178(4059):414–416. https://doi.org/10.1126/science.178.4059.414
Lockwood AH, et al. Effects of phenylalanine administration on CNS tyrosine and dopamine. Am J Clin Nutr. 1986;44(3 Suppl):543–547. https://doi.org/10.1093/ajcn/44.3.543
Lejoyeux M, Adès J. Phenylalanine and depression: therapeutic implications. J Affect Disord. 1992;26(2):109–115. https://doi.org/10.1016/0165-0327(92)90074-F