L-phenylalanine (LPA) serves as a building block for the various proteins that are produced in the body. L-phenylalanine can be converted to L-tyrosine and subsequently to L-dopa, norepinephrine, and epinephrine. L-phenylalanine can also be converted (through a separate pathway) to phenylethylamine, a substance that occurs naturally in the brain and appears to elevate mood.

D-phenylalanine (DPA) is not normally found in the body and cannot be converted to L-tyrosine, L-dopa, or norepinephrine. As a result, DPA is converted primarily to phenylethylamine (a potential mood elevator). DPA also appears to influence certain chemicals in the brain that relate to pain sensation.

DLPA is a mixture of the essential amino acid LPA and its mirror image DPA. LPA is found in most foods that contain protein. DPA does not normally occur in food, but when synthesized in the laboratory, half appears as LPA and half as DPA. The combination supplement (DLPA) is often used because both components exert different health-enhancing effects.

Although rare, individuals whose diets are very low in protein may develop a deficiency of L-phenylalanine. Benefits of supplementation are typically achieved in the absence of an outright deficiency.

DLPA has been used in amounts ranging from 75 to 1,500mg per day. Consistent toxicity in healthy people has not been reported with 1,500mg per day or less of DLPA, except for occasional nausea, heartburn, or transient headaches.

This compound can have powerful effects on mood and on the nervous system, and therefore DLPA should be taken only under medical supervision.

People with phenylketonuria must not supplement phenylalanine. Some research suggests that tardive dyskinesia patients may process phenylalanine abnormally. Until more is known, it makes sense for people with this condition to avoid phenylalanine supplementation.

Since DLPA competes with other amino acids for attachment on a common amino acid carrier in the body, it should not be taken with protein containing foods. Individuals taking prescription or over-the-counter medications should consult a physician before taking DLPA.


Phenylalanine can help with the following


Parkinson's Disease / Risk

D-phenylalanine (DPA) may be helpful for some individuals with Parkinson’s disease. [Arzneimittelforsch 26: pp.577-9, 1976]




Phenylalanine can affect depression via three separate pathways.


Rheumatoid Arthritis

The ‘D’ form of phenylalanine (DPA) has been used to treat chronic pain, including rheumatoid arthritis, with mixed effectiveness.



D-phenylalanine (DPA) has been used to treat the chronic pain of osteoarthritis with both positive and negative results.


Low Back Pain / Problems

The brain responds to pain signals by producing and activating morphine-like hormones called endorphins. This pain relief effect lasts for about 30 hours (longer than known analgesics), and without side effects when given frequently. It was discovered that d- and dl-Phenylalanine (DLPA), but not l-Phenylalanine, inhibit several of the enzymes responsible for endorphin destruction. DLPA appears to restore endorphin levels to a normal range, while simultaneously producing a reduction in pain. It often equals or exceeds morphine or other opiate derivatives in its effect and is non-addictive. Start with 500mg qd and work up to 3 or 4gm qd. This is a precursor for epinephrine and phenylethylamine (PEA). PEA has amphetamine-like stimulant properties. Chocolate contains high levels of PEA.


May do some good
Likely to help
May have adverse consequences



Compounds composed of hydrogen, oxygen, and nitrogen present in the body and in foods that form complex combinations of amino acids. Protein is essential for life and is used for growth and repair. Foods that supply the body with protein include animal products, grains, legumes, and vegetables. Proteins from animal sources contain the essential amino acids. Proteins are changed to amino acids in the body.


(Norepinephrine): A catecholamine hormone secreted from the adrenal medulla and post-ganglionic adrenergic fibers in response to hypotension or emotional stress.


D.L-Phenylalanine: A 50-50 mixture of d-phenylalanine and l-phenylalanine. May help alleviate chronic pain by increasing endorphin activity (the body s natural painkillers).

Amino Acid

An organic acid containing nitrogen chemical building blocks that aid in the production of protein in the body. Eight of the twenty-two known amino acids are considered "essential," and must be obtained from dietary sources because the body can not synthesize them.


(mg): 1/1,000 of a gram by weight.


Symptoms resulting from an inclination to vomit.

Nervous System

A system in the body that is comprised of the brain, spinal cord, nerves, ganglia and parts of the receptor organs that receive and interpret stimuli and transmit impulses to effector organs.


An inherited disease caused by a lack of an enzyme necessary for converting phenylalanine into a form the body can use.


Essential amino acid needed for the normal growth of infants and children. It is also needed for normal protein use all through life. Precursor to tyrosine which is used to manufacture certain hormones (epinephrine, norepinephrine, dopa, dopamine) which are important for the transmission of nerve impulses. As neurotransmitters, these substances are believed to influence mood, appetite control and memory. It is found in large amounts in milk, eggs, and other common foods.


A condition characterized by spasmodic, uncoordinated, or other abnormal movements; i.e., those which result from a reaction to phenothiazines.


A drug or medication that can legally be bought without a doctor's prescription being required.

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