Phenylalanine
L-phenylalanine (LPA) serves as a building block for the various proteins that are produced in the body. LPA can be converted to L-tyrosine (another amino acid) and subsequently to L-dopa, norepinephrine, and epinephrine. LPA can also be converted (through a separate pathway) to phenylethylamine, a substance that occurs naturally in the brain and appears to elevate mood.
- Reliable and relatively consistent scientific data showing a substantial health benefit.
- Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
- For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.
Our proprietary “Star-Rating” system was developed to help you easily understand the amount of scientific support behind each supplement in relation to a specific health condition. While there is no way to predict whether a vitamin, mineral, or herb will successfully treat or prevent associated health conditions, our unique ratings tell you how well these supplements are understood by the medical community, and whether studies have found them to be effective for other people.
For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.
This supplement has been used in connection with the following health conditions:
| Used for | Amount | Why |
|---|---|---|
Depression | 3 to 4 grams L-phenylalanine or 150 to 200 mg of DL-phenylalanine daily |  [2 stars] In one study, depressed people given L-phenylalanine experienced results comparable to those produced by an antidepressant. |
Low Back Pain | 1,500 to 2,500 mg per day of DL-Phenylalanine | [2 stars] Several studies suggest that a synthetic version of phenylalanine called D-phenylalaline, may reduce pain by decreasing the enzyme that breaks down endorphins. |
Pain | 1,500 mg daily | [2 stars] D-phenylalanine (DPA) decreases pain by blocking the enzymes that break down the body’s natural painkillers. Clinical studies suggest DPA may inhibit some types of chronic pain. |
Parkinson’s Disease | Consult a qualified healthcare practitioner | [2 stars] In one trial, D-phenylalanine (DPA) supplementation improved motor control and tremors in people with Parkinson’s disease. DPA should not be taken with L-dopa as it may interfere with the transport of L-dopa to the brain. |
Vitiligo | 50 mg daily per 2.2 lbs (1 kg) of body weight, with ultraviolet light exposure | [2 stars] L-phenylalanine, in conjunction with ultraviolet light exposure, may improve repigmentation of skin. |
Alcohol Withdrawal (Glutamine, L-Tyrosine, Multivitamin, L-Tryptophan) | Refer to label instructions |  [1 star] In double-blind research, alcoholics treated with L-tyrosine combined with DLPA (D,L-phenylalanine), L-glutamine, prescription L-tryptophan, plus a multivitamin had reduced withdrawal symptoms and decreased stress.
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Alcohol Withdrawal and Food Allergies | Refer to label instructions | as D,L-Phenylalanine (DLPA)[1 star] In double-blind research, alcoholics treated with DLPA (D,L-phenylalanine) combined with L-tyrosine, L-glutamine, prescription L-tryptophan, plus a multivitamin had reduced withdrawal symptoms and decreased stress.
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Osteoarthritis | Refer to label instructions | [1 star] Supplementing with D-phenylalanine (DPA) has been shown to reduce chronic pain due to osteoarthritis. DPA inhibits the enzyme that breaks down some of the body’s natural painkillers. |
Rheumatoid Arthritis | Refer to label instructions | [1 star] D-phenylalanine has been used with mixed results to treat chronic pain, including pain caused by rheumatoid arthritis. |
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The information presented by TraceGains is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. Self-treatment is not recommended for life-threatening conditions that require medical treatment under a doctor's care. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires December 2025.