About Phenylalanine
Essential amino acid and precursor to tyrosine, dopamine and norepinephrine. As a free-form supplement it overlaps heavily with dietary protein, so standalone supplementation adds little in people eating adequate protein. DL-phenylalanine (DLPA) has been promoted for chronic pain (endorphin/enkephalin sparing) and depression, but the trials are small, old and largely null on careful re-examination. CONTRAINDICATED in phenylketonuria (PKU). Grade low: mechanism is clear but clinical efficacy as a standalone supplement is unproven.
What Phenylalanine supports
- Precursor to tyrosine and dopamine/norepinephrine (mechanistic)
- DLPA marketed for pain and mood, but clinical evidence is limited and mixed
How much Phenylalanine to take
The RDA prevents deficiency. The effective range is what clinical trials used to actually move the outcome.
Effective
500–1500
mg
No established therapeutic supplement dose; nominal range for a blend component. DLPA (D,L-phenylalanine) pain/mood studies used ~150-1500 mg/day. Essential amino acid amply supplied by dietary protein.
Clinical evidence
Limited clinical evidence. Essential amino acid; standalone supplement evidence weak and largely null. Contraindicated in PKU.
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