Synonyms/Common Names/Related Substances:
- Alpha-aminohydrocinnamic acid, beta-phenyl-alanine, Cari Loder regime, DLPA, D-phenylalanine, DL-phenylalanine, L-phenylalanine.
Clinical Bottom Line/Effectiveness
Brief Background:
- As a dietary supplement, phenylalanine is commercially available as L-phenylalanine, D-phenylalanine, and DL-phenylalanine. Of the two enantiomers of phenylalanine, L-phenylalanine is an essential amino acid for humans; proteins only contain this form of phenylalanine. The role in humans of the other enantiomer, D-phenylalanine, is uncertain. DL-phenylalanine is a synthetic product of 50% D-phenylalanine and 50% L-phenylalanine. In the 1960s there were medical publications of initial studies that described the dietary supplement's familiar use for depression, and in the 1970s medical documentation began for another familiar use, pain.
- Depression is a common use for L-phenylalanine or DL-phenylalanine. Pain is a common use for D-phenylalanine.
- The medical literature somewhat substantiates depression as a use for L-phenylalanine or DL-phenylalanine, whereas evidence is lacking for the effectiveness of D-phenylalanine for pain. For vitiligo, non-randomized trials describe the effectiveness of L-phenylalanine in combination with irradiation with ultraviolet A (UVA) or exposure to sunlight; some European studies report the effectiveness of this combination with the addition of a cream or gel of 10% phenylalanine but such topical preparations are not domestically available.
- Substantive adverse effects were that Parkinson's disease worsened with DL-phenylalanine, and tardive dyskinesia worsened with L-phenylalanine.
Dosing/Toxicology
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Precautions/Contraindications
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Interactions
Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy.
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Mechanism of Action
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History
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Evidence Table
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Evidence Discussion
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Products Studied
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Author Information
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References
Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.
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