What is DL-Phenylalanine?

Phenylalanine is one of the essential amino acids, meaning that it is only available to the body through food. It is mainly found in the following foods:

• pumpkin seeds
• poultry
• chicken egg
• unpolished rice
• pork
• Salmon
• Peas
• walnuts

Phenylalanine is needed to build proteins and is also the precursor for many hormones that regulate various functions in the body; among other things, it is needed for proper brain, nerve and cardiovascular function.

DL-phenylalanine (DLPA) is a mixture of the essential amino acid L-phenylalanine and the equivalent amount of the mirror-symmetrical form D-phenylalanine.

Health Benefits of L-Phenylalanine

// Phenylalanine is an essential amino acid that the body needs to produce the happiness hormone dopamine, among other things. Due to its role as an important precursor to dopamine, scientific findings also suggest that it is able to improve our performance, especially in stressful situations. //

In the human body, L-phenylalanine is used to produce proteins, but its role in the production of neurotransmitters is even more important.

Tyrosine is formed by the hydroxylation of phenylalanine, a process in which the enzyme phenylalanine hydroxylase acts as a catalyst.

Tyrosine performs many important functions in your body, including the formation of hormones such as thyroxine and Insulin, as well as neurotransmitters and catecholamines (the “happiness hormone” dopamine, as well as noradrenaline and adrenaline). The latter act as messenger substances that stimulate nerve cells.

The neurotransmitters control our “emotional and mental apparatus” and regulate vital functions such as heart rate and blood pressure.
Researchers were able to prove in a study that an increased concentration of L-phenylalanine, as the first intermediate step of dopamine, seems to have a positive effect on our mood and also improves concentration – especially in stressful situations (cf. https://www.ncbi.nlm.nih.gov/pubmed/10633491 and https://www.ncbi.nlm.nih.gov/pubmed/7794222).

L-phenylalanine and the mirror-symmetrical form D-phenylalanine can also be converted into the neurotransmitter phenylethylamine (PEA). This interesting amino acid has the potential to produce a stimulating and mood-enhancing effect (cf. Sabelli HC, Javaid JI. Phenylethylamine modulation of affect: therapeutic and diagnostic implications. J Neuropsychiatry Clin Neurosci. 1995 Winter;7(1):6-14).

PEA is released by brain cells when you are euphoric or in love. Chocolate, for example, contains relatively high amounts of PEA. Other foods that have a significant PEA content include salami, pickled herring and cheddar cheese.

There is evidence that low PEA levels can lead to a melancholic mood. Human clinical trials have shown that PEA supplementation has the potential to improve mood (see Davis BA, O'Reilly RL, Placatka CL, Paterson IA, Yu PH, Durden DA. Effect of dietary phenylalanine on the plasma concentrations of phenylalanine, phenylethylamine and phenylacetic acid in healthy volunteers. Prog Neuropsychopharmacol Biol Psychiatry. 1991;15(5):611-23).

Clinical studies have also shown that taking a DLPA supplement can improve mood. Whereas L-phenylalanine would have to be supplemented in relatively high doses of up to 10 g/day, in the case of DLPA a dose of 200 mg/day is sufficient for initial positive effects (cf. Fischer E, Heller B, Nachon M, Spatz H. Therapy of depression by phenylalanine. Preliminary note. Arzneimittelforschung. 1975 Jan;25(1):132; Beckmann H, Strauss MA, Ludolph E. Dl-phenylalanine in depressed patients: an open study. J Neural Transm. 1977;41(2-3):123-34; Beckmann H, Athen D, Olteanu M, Zimmer R. DL-phenylalanine versus imipramine: a double-blind controlled study. Arch Psychiatr Nervenkr (1970). 1979 Jul 4;227(1):49-58).

Studies have shown that the administration of DL-phenylalanine can reduce symptoms such as fatigue and irritability when used in addition to conventional treatment methods. The following mechanism underlies this effect: Phenylalanine makes it more difficult for enzymes to work, which in turn contribute to the breakdown of endorphins and enkephalins. Therefore, the endorphin level is higher after consuming phenylalanine. (cf. http://www.jbc.org/content/264/22/12849.full.pdf). This means that, among other things, less GABA is released, which in turn correlates with an increased release of the happiness hormone dopamine.

About one-third of the D-phenylalanine in DLPA is converted to L-phenylalanine. The remaining D-phenylalanine may have other unique effects than L-phenylalanine. For example, D-phenylalanine (DPA) has shown effects in experimental models of the body's pain-relieving endorphin system that suggest it could be used to treat chronic pain, inflammation, and drug addiction.

Possible side effects

People suffering from the rare genetic disorder phenylketonuria (PKU) must avoid any form of phenylalanine. After conducting studies on patients who do not have this genetic defect, researchers concluded that taking L- and D-phenylalanine and DLPA in the usual doses does not cause any significant side effects and therefore there are no concerns about safety.