Phenylalanine is an amino acid that helps the body to build proteins. Most commonly, cosumers find phenylalanine in gum. They notice the warning labels on products, which alerts them to the presence of phenylalanine and are concerned about its effects. It is not a risk to the majority of consumers; these warnings benefit people with phenylketonuria, a disease where the body cannot digest the chemical.

Phenylalanine occurs as a byproduct when the common sweetener aspartame breaks down in the body; manufacturers do not add the substance to products. Understanding phenylalanine is important to help answer questions regarding its safety, purpose, benefits, and its side effects.

chewing gum on table

What Is Phenylalanine?

Phenylalanine is a necessary amino acid not produced by the human body.

It is available in three forms:

  • L-phenylalanine – the natural form which occurs in various foods like meat, fish, eggs, cheese, and milk
  • D-phenylalanine – synthetic form of phenylalanine, it has the ability to inhibit the actions of enzymes that affect the brain and nervous system and is available only as an additive or supplement.
  • DL-phenylalanine – a combination of the 2 forms available in additive or supplement formula

For the majority of the population, phenylalanine in gum is not a health risk; however, those with the condition known as phenylketonuria, phenylalanine in gum made with aspartame may experience seizures or brain damage upon ingestion.

Phenylalanine is an amino acid and essential for humans since it is considered a building block of protein. Phenylalanine helps the body carry out important functions. Amino acids that are produced from phenylalanine make proteins and help with molecule conversion. Phenylalanine is also necessary for the production of epinephrine and norephedrine, most commonly known for being connected to the fight or flight response humans have when stressed.

Our bodies need dopamine to experience feelings of well-being, and phenylalanine aids in the production of dopamine. Because of this, there is speculation that phenylalanine can help in cases of depression, though research supporting this claim is inconsistent.

Phenylalanine can help with skin disorders and is used to treat certain types of pain. In fact, besides being present in food, phenylalanine can be prescribed as medication for people with specific health problems.

There are various groups who believe these products are dangerous and propose the banning of phenylalanine and aspartame.Individuals have asserted that consuming phenylalanine via aspartame has caused numerous ailments including headaches, nausea, dizziness, forgetfulness, and nervousness. While it is not possible to account for every individual’s experience, the U.S. FDA approves aspartame and phenylalanine in gum and other products.

Products that Contain Phenylalanine

While phenylalanine occurs naturally in foods, especially those with high proteins such as meat, eggs, milk, seafood, and cheese. Approximately 85% of chewing gums use aspartame, which breaks down into phenylalanine. This leaves consumers who wish to avoid phenylalanine in gum very few options.

Because phenylalanine is a byproduct occurring after the breakdown of aspartame, it does not appear as an ingredient. In the interest of protecting those with phenylketonuria, products which contain aspartame (and once broken down phenylalanine) carry the following warning:


Of course, there are products that contain phenylalanine as an additive, such as diet sodas, gum, and low-sugar or sugar-free products. Many of these products carry a warning that they contain phenylalanine, and since phenylalanine is in aspartame, any product that contains aspartame has phenylalanine in it.

Due to concerns over the effects of aspartame, assumptions are often made that phenylalanine is dangerous to consume. For most people, this simply isn’t true. Product warnings are there for the percentage of the population who suffer from phenylketonuria, also known as PKU.

This rare genetic disorder makes it impossible for the body to break down phenylalanine. Those diagnosed with PKU have to follow a lifelong diet that limits phenylalanine, hence the need for products with phenylalanine as an additive to be labeled.

Phenylalanine is present in some medications, so anyone with PKU needs to make sure that their over-the-counter and prescription drugs are free of it. Phenylalanine can also be prescribed for medical use.

Because aspartame is widely used, the brands of gum are extensive. The following is a list of commonly known gum varieties with phenylalanine. Remember that not all of these are sugar-free, yet they are required to have the warning and list aspartame as an ingredient.

  • BUBBLE YUM-Hershey, USA;
  • DUBBLE BUBBLE – Concord Confections, Canada;
  • JUICY FRUIT- Wrigley, Canada, USA;
  • MENTOS- Netherlands;
  • TRIDENT- Cadbury, Canada.

gumballs on a blanket

Dangers of Phenylalanine

  1. Persons with the disorder phenylketonuria must avoid products with aspartame and phenylalanine supplements as life-threatening conditions may occur if ingested. Those who have phenylketonuria should look for and heed all warning labels on gum and other products.
  2. Those taking certain medications, such as monoamine oxidase inhibitors or neuroleptics, should not consume phenylalanine.
  3. Persons who have tardive dyskinesia or other muscular movement disorders should avoid phenylalanine.
  4. Anyone who takes a medication containing the drug levodopa should not ingest phenylalanine.
  5. Those who have a sleep disorder should limit or avoid products with phenylalanine as they may worsen the sleep disorder or cause jitteriness.
  6. Persons who have reason to believe they have experienced an adverse reaction to aspartame or phenylalanine in the past should not consume these products.

Are there Benefits for Phenylalanine?

Phenylalanine in gum and other food products has a stigma that overshadows its positive attributes. Apart from its appearance in the body after ingestion of aspartame, phenylalanine (one of eight essential amino acids which the human body does not produce) is present naturally in high protein foods. In their natural form, they pose no harm to humans and are critical to the normal functioning of the central nervous system.

Synthesized phenylalanine supplements help improve memory, boost alertness, and enable the nervous system to operate efficiently. Additionally, doctors use phenylalanine to treat anxiety, depression, chronic pain, bipolar disorder, and hyperactivity. Various medical trials study its use for treating migraines and other headaches, arthritis, and menstrual cramps as well as a supplement for concentration and alertness.

Frequently Asked Questions Surrounding Phenylalanine

Is phenylalanine good for everyone?

Overall, in appropriate amounts, phenylalanine is considered safe for most people. However, there are exceptions. Those who have been diagnosed with phenylketonuria are not safe consuming phenylalanine. It’s considered toxic for them.

People who take medication for schizophrenia may also want to be careful when it comes to phenylalanine consumption. Tardive dyskinesia, a condition that causes the face and body to jerk and become stiff, can occur when a person is taking an antipsychotic to treat schizophrenia. Phenylalanine consumption may further aggravate the symptoms of tardive dyskinesia.

Can I get too much phenylalanine?

Unless there are special circumstances, not usually. It’s safe and necessary for most people to consume phenylalanine through food since it aids in important functions of the body.

If pregnant, should phenylalanine be consumed?

Phenylalanine supplements should not be consumed by pregnant women, but food containing phenylalanine is generally fine. An exception would be if a woman is found to have high phenylalanine levels.

When this is the case, a doctor will likely recommend the patient lessen her intake of phenylalanine through food because too much during pregnancy has been linked to birth defects.

How do I know if I suffer from PKU?

In the United States, most doctors perform PKU screenings at birth. A child will have blood taken from his foot to see if he has the condition before symptoms are even present.

Can I be allergic to phenylalanine even if I don’t have PKU?

It is possible to be allergic to a supplement form of phenylalanine. Reactions are typical for allergic responses and can include:

  • itching
  • swelling
  • trouble breathing

There are other milder side effects when taking phenylalanine in supplement form, and nerve damage can occur if more than 5,000 milligrams a day is consumed.


Some of the claims against phenylalanine in gum appear to be over-stated. The United States Food and Drug Administration has judged it to be safe for consumption unless an individual is afflicted with phenylketonuria. Furthermore, warnings are mandated for gum and all other products containing aspartame as it breaks down into phenylalanine.

While individual experiences and reactions differ, writing it off as dangerous seems unwarranted. If you have experiences or thoughts about phenylalanine in gum, please feel free to comment, tweet, or Facebook, as exchanging ideas can be helpful in expanding knowledge and understanding.

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