Skip to content


The Power of Phenylalanine: The Amino Acid That Helps to Transform Your Health

The Power of Phenylalanine: The Amino Acid That Helps to Transform Your Health

Article At A Glance

Phenylalanine is an essential amino acid that cannot be synthesized in the body and is crucial for building proteins and maintaining bodily function.

Phenylalanine has many benefits, including enhancing cognitive function, improving mood, building proteins, stimulating growth hormone, and supporting weight loss.

Phenylalanine supplements can be incorporated into the diet through recovery formulas or pre-workout supplements, but precautions outlined in this article should be taken.

Product Recommendations
Isolated Supplement - L-Phenylalanine by Healthwise
Muscle Growth and Repair - Resurrect Growth and Recovery Matrix by UM Sports
Pre-Workout - Cross Eyed by Zombie Labs

Phenylalanine has gained significant popularity as a sports supplement due to its performance, recovery, and overall health benefits.

In this article, we aim to explore the science behind Phenylalanine, its various benefits, and the most effective methods of integrating it into a training regimen.

What is Phenylalanine?

Phenylalanine is an essential amino acid and cannot be synthesized in the body, making it necessary to consume it through diet or supplementation.

After ingestion, it converts to tyrosine and synthesizes essential molecules such as dopamine, norepinephrine, and epinephrine. Overall, Phenylalanine acts as a crucial building block for proteins, thus playing a pivotal role in maintaining optimal bodily function.

There are three forms of Phenylalanine:

  • L-phenylalanine is naturally present in protein-rich foods such as meat, fish, and dairy products, as well as some plant-based sources like soybeans and quinoa.
  • D-phenylalanine’s physiologic function remains largely unknown.
  • DL-phenylalanine is synthetically produced in a lab.

Benefits of Phenylalanine

Phenylalanine is an essential amino acid with many benefits for athletes and non-athletes.

  1. Enhances cognitive function: Phenylalanine may enhance cognitive function, improving memory, focus, and attention, making it an ideal supplement for athletes who need to stay focused and alert during training and competition.
    1. Enhances mood & cognitive function: Helps produce neurotransmitters such as norepinephrine and epinephrine, and dopamine, which play a key role in stress regulation, mood, and energy levels.  A deficiency in this important amino acid can cause a long list of symptoms, including confusion, depression, memory loss and low energy levels.
  • Builds proteins: Phenylalanine is one of the building blocks of proteins, and it plays a crucial role in synthesizing other amino acids, such as tyrosine and tryptophan.
  • Stimulates growth hormone: Phenylalanine stimulates the production of growth hormone, which is essential for muscle growth and repair.
  • Supports weight loss: Phenylalanine may reduce hunger and support weight loss efforts by suppressing appetite and increasing feelings of fullness.

Incorporating Phenylalanine Supplements

There are several ways to incorporate Phenylalanine into your diet through supplements. The recommended dose of L-phenylalanine for adults is 100-250 mg/kg by mouth daily for up to 3 months.

Option 1: Drink a recovery formula after a workout containing Phenylalanine and other amino acids to support muscle growth and repair.

Option 2: Take a pre-workout before exercise containing Phenylalanine to help increase your energy levels, mood, and alertness during exercise.


Phenylalanine is generally considered safe when taken in recommended doses. However, some people may experience side effects, such as headaches, nausea, and heartburn.

  • Phenylalanine supplements should not be taken by individuals with phenylketonuria (PKU), a rare genetic disorder that affects the body's ability to process phenylalanine.
  • Pregnant women should also avoid taking phenylalanine supplements, as there is insufficient safety information on the use of Phenylalanine and the developing fetus.
  • Phenylalanine may decrease the absorption of baclofen, a form of muscle relaxant medication used to treat muscle stiffness and tightness.
  • Levodopa interacts with PHENYLALANINE.
  • Levodopa is used for Parkinson disease and taking Phenylalanine in combination with this medication may worsen symptoms of Parkinson’s disease.
  • The competition of levodopa with Phenylalanine and tyrosine for intestinal transport pathways is probably the major effect of levodopa therapy on the metabolism of these amino acids.

It's important to talk to a healthcare professional before starting new supplements to ensure they are safe and appropriate for your needs.


Phenylalanine is an essential amino acid that is important to produce proteins and neurotransmitters in the body, making it beneficial for mood regulation, pain reduction, promoting weight loss, and maintaining skin health.

Phenylalanine supplements should be taken with caution and under the guidance of a healthcare provider, especially in individuals with PKU or during pregnancy.


  • Ajmera, R. (2021, November 12). Phenylalanine: Benefits, side effects, and Food Sources. Healthline. Retrieved May 8, 2023, from
  • Earp, J. E., Colon-Semenza, C., & LoBuono, D. L. (2023). Considerations for developing a targeted amino acid supplement for people with parkinson’s disease that promotes health while accounting for pathophysiology and medication interference. Nutrition Reviews.
  • (n.d.). Phenylalanine: Overview, uses, side effects, precautions, interactions, dosing and reviews. WebMD. Retrieved May 8, 2023, from


Teigen Faux, Exercise Physiologist (Honours)

Stephen Brumwell, Nutritionist (ANTA #40048) for Scientific Accuracy

Previous article Glutamine: Understanding the Basics of this Critical Amino Acid
Next article Leucine: Benefits, Doses and Side Effects Explained