Amino Acid
Phenylalanine
SaveAn essential amino acid and precursor to tyrosine, which in turn produces dopamine, norepinephrine, and epinephrine. Available in L-, D-, and DL- forms with different applications.
Quick verdict
Adequate dietary intake supports catecholamine synthesis. Supplementation beyond dietary needs has limited evidence for cognitive or mood benefits in healthy individuals.
Evidence score
A rough internal score reflecting quantity, quality, and consistency of human evidence. Not a clinical recommendation.
What the research shows
L-phenylalanine is an essential amino acid obtained through diet. D-phenylalanine has been studied for pain (via enkephalinase inhibition) with mixed results. DL-phenylalanine has preliminary data for depression. Most individuals obtain sufficient phenylalanine from dietary protein.
Benefits
- Essential precursor in the catecholamine synthesis pathway
- DL-form has preliminary antidepressant data
- D-form may modulate enkephalin breakdown
Dosage notes
500–1500 mg/day if supplementing. Most people get sufficient amounts from dietary protein.
Side effects
- Headache
- Nausea
- Anxiety at high doses
- Contraindicated in PKU
Who should be cautious
Contraindicated in phenylketonuria (PKU). May interact with MAOIs and L-DOPA. Caution with anxiety disorders as it may increase catecholamine tone.
What this page cannot tell you
Supplementation is unlikely to benefit people with adequate protein intake. D-phenylalanine pain data is old and poorly replicated.
Leaderboard scores
- Mood40
- Focus35
- Energy30
- Pain30
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