Table of Contents

Phenylalanine Side Effects

Takeaways

  • Phenylalanine is an essential amino acid found in many foods and supplements
  • It’s generally safe for most people but can cause side effects in some
  • People with PKU must strictly limit phenylalanine intake
  • Common side effects include headaches, nausea, and anxiety
  • Rare but serious side effects may include seizures or allergic reactions
  • Consult a doctor before taking phenylalanine supplements

Understanding Phenylalanine

Phenylalanine is an essential amino acid that the human body needs to build proteins.[1] We obtain it through the foods we eat and sometimes through supplements. This amino acid plays a role in many bodily processes.

Phenylalanine exists in different forms. L-phenylalanine is the natural form, commonly found in foods like meat, fish, and eggs.[2] Our bodies can readily use this naturally occurring form.

D-phenylalanine is a synthetic version of phenylalanine that is created in a laboratory and is often included in supplements.[3] Some products contain a mixture of both L-phenylalanine and D-phenylalanine, called DL-phenylalanine.[4]

Types of Phenylalanine

L-Phenylalanine

L-phenylalanine is found naturally in many foods, and our bodies are well-equipped to process and use it. It is a component of the proteins present in many common foods.

L-phenylalanine is present in meats, dairy products, and eggs, as well as plant-based sources such as soy products and some nuts.[5] The body cannot produce it so we must get it from our diets or supplements.[6]

D-Phenylalanine

D-phenylalanine is created synthetically in laboratories. It is a mirror image of the L-form, and the body processes it through a different pathway than L-phenylalanine.[7]

Some people believe D-phenylalanine can help with pain management, however research on this is still underway.[8] It is not found naturally in food sources, so supplementation is the only source.[9]

DL-Phenylalanine

DL-phenylalanine is a blend of L-phenylalanine and D-phenylalanine. This combination of both forms is frequently found in dietary supplements.[10]

DL-phenylalanine is used for various reasons, including to potentially improve mood or help with pain, although more research is still being conducted to determine its full effects.[11]

Phenylalanine in the Body

The body utilizes phenylalanine in a multi-step process that starts in the digestive system. Once digested, it is absorbed into the bloodstream to be distributed throughout the body.

The liver converts most of the phenylalanine into another amino acid called tyrosine.[12] Tyrosine is important for producing crucial brain chemicals.[13]

Process Description
Digestion Breakdown of proteins containing phenylalanine
Absorption Phenylalanine enters the bloodstream
Conversion Liver changes phenylalanine to tyrosine
Utilization Body uses phenylalanine and tyrosine for various functions

Phenylalanine is involved in producing neurotransmitters, which are chemical messengers in the brain.[14] Dopamine and norepinephrine are two examples of neurotransmitters it helps to create.

Potential Benefits of Supplementation

Some people choose to take phenylalanine supplements to try and achieve certain health benefits. However, research on the effectiveness of this is showing mixed results.[15]

The potential benefits of using phenylalanine supplements may include:

  • Mood improvement
  • Pain relief
  • Skin condition treatment
  • ADHD symptom management

Some studies suggest phenylalanine might have a role in managing depressionand easing chronic pain, but more research is needed to confirm these potential benefits.[16]

Common Side Effects

Taking phenylalanine supplements may result in some side effects, although not everyone will experience them. It’s important to understand the potential risks.

Side effects are more likely to occur with larger doses of phenylalanine, as the body may have difficulty processing high amounts, which can lead to various symptoms.[17]

The most common side effects of phenylalanine are:

  1. Headaches
  2. Nausea
  3. Heartburn
  4. Anxiety
  5. Sleep problems

Side effects associated with phenylalanine supplements are typically mild and often resolve on their own.[18] Reducing the dosage can often help to manage these effects.

Rare but Serious Side Effects

Although less common, some individuals may experience severe reactions. These serious side effects require immediate medical attention because they can be dangerous if not treated.

Certain groups are more likely to experience serious side effects from phenylalanine supplements. Those with pre-existing health conditions or taking specific medications may be at increased risk.[19]

Rare, but serious side effects of phenylalanine may include:

  • Seizures
  • Allergic reactions
  • Severe mood changes
  • High blood pressure

If you experience any of these serious side effects, it’s important to stop taking phenylalanine and seek medical help right away. A doctor can assess your situation and provide appropriate guidance.

Interactions with Medications

Phenylalanine can interact with some medications, altering how they function or increasing the risk of side effects.[20] This makes it important to be cautious.

It is important to inform your doctor about all supplements you are taking, as this helps to avoid potentially harmful interactions with medications. This is particularly important when starting any new medications.

Medication Type Potential Interaction
MAO Inhibitors May increase risk of high blood pressure
L-dopa Might reduce effectiveness of Parkinson’s treatment
Thyroid medications Could interfere with absorption
Antipsychotics May alter effectiveness or side effects

Medication interactions can be complex and depend on several factors. Your doctor can help you understand your specific risk profile based on your medication and health history.

Risk Factors and Contraindications

Some individuals are at a higher risk of experiencing side effects from phenylalanine supplements. Certain health conditions make supplementation potentially risky. Knowing if you are in a high-risk group is crucial.

Health conditions that may increase the risks associated with phenylalanine use include:

  • Phenylketonuria (PKU)
  • Schizophrenia
  • Tardive dyskinesia
  • Pigmented melanoma

Pregnant women should exercise caution when using phenylalanine supplements. High levels of phenylalanine may potentially harm the developing baby.[21] It is essential to consult a doctor before taking supplements during pregnancy.

Phenylketonuria (PKU) and Phenylalanine

Phenylketonuria (PKU) is a rare genetic disorder in which people cannot properly process phenylalanine.[22] This can lead to a dangerous buildup of the amino acid in the body.

For those with PKU, even typical amounts of phenylalanine can be harmful.[23] People with PKU must adhere to a strict low-phenylalanine diet, avoiding many common food sources.

If PKU is left untreated, it can cause serious health issues, including brain damage and developmental delays.[24] This is why newborn screening for PKU is standard practice in many countries.

Safe Dosage and Usage

Finding the right dosage of phenylalanine is important. Too little won’t provide any benefit, while too much can raise the risk of side effects.[25] The ideal dosage will vary from person to person.

Factors that can affect what a safe dosage of phenylalanine is may include:

  • Body weight
  • Overall health
  • Reason for taking it
  • Other medications or supplements

General guidelines for using phenylalanine safely include:

  1. Consult a healthcare provider
  2. Start with a low dose
  3. Monitor for side effects
  4. Increase slowly if needed
  5. Don’t exceed recommended amounts

It is important to always follow the instructions on the supplement label. However, getting personalized advice from a doctor or nutritionist is recommended.

Monitoring and Managing Side Effects

Monitoring for side effects is crucial when using phenylalanine. Pay attention to how you feel after taking phenylalanine to help identify any potential problems early on.

Methods for monitoring the effects of phenylalanine include:

  • Keep a symptom diary
  • Note changes in mood or energy
  • Track sleep patterns
  • Record any physical discomfort

Signs that may indicate you should adjust or stop your phenylalanine supplementation are:

  • Persistent headaches
  • Unusual mood swings
  • Digestive issues
  • Sleep disturbances

If you’re uncertain about any symptoms, talking to your doctor is important. They can help determine if the symptoms are related to phenylalanine and advise whether you should continue using it.

Alternatives to Phenylalanine Supplements

Many people can get enough phenylalanine from the foods they eat. A well-balanced diet will often provide all that we need. Whole food sources are typically safer than supplements.[26]

Foods that are natural sources of phenylalanine include:

  • Lean meats
  • Fish
  • Eggs
  • Dairy products
  • Nuts and seeds
  • Soy products

For those seeking alternative options, lifestyle adjustments, other supplements, or different treatments may be beneficial depending on the person and the reason for seeking phenylalanine in the first place.

Balancing your diet can assist in managing your phenylalanine intake. Collaborating with a nutritionist can help you create a plan that meets your individual needs, ensuring you get the right nutrients without overdoing it.

Regulatory Status and Quality Control

In the U.S., the Food and Drug Administration (FDA) regulates dietary supplements, but the rules are less strict than for prescription drugs.[27] This can result in variations in product quality.

Choosing supplements from reputable brands is important to ensure quality. Look for manufacturers that follow good manufacturing practices.[28] Third-party testing can also help indicate product quality.

Tips for choosing high-quality phenylalanine supplements are:

  • Check for certifications (e.g., USP, NSF)
  • Read customer reviews
  • Look for clear labeling
  • Choose established brands
  • Avoid products with extreme claims

Understanding supplement labels is helpful when choosing a supplement. It’s important to be aware of what claims actually mean and to be skeptical of any products promising miraculous results.

FAQ

Is phenylalanine safe for everyone?
No, it’s not safe for everyone. People with PKU or certain health conditions should avoid it. Always check with a doctor before taking supplements.[29]

Can phenylalanine cause weight gain?
There’s no strong evidence that phenylalanine directly causes weight gain. But it might affect appetite in some people. Monitor your weight if you start taking it.[30]

How long does it take for phenylalanine to work?
Effects can vary. Some people notice changes within a few days. For others, it might take weeks. Consistency is often key for seeing results.

What are the signs of phenylalanine toxicity?
Signs may include severe headaches, confusion, or high blood pressure. In extreme cases, seizures can occur. Seek medical help if you suspect toxicity.[31]

Can phenylalanine interfere with sleep?
Yes, it can for some people. Phenylalanine might increase alertness. Taking it late in the day could disrupt sleep patterns. Try taking it earlier if you notice sleep issues.[32]

Is phenylalanine the same as aspartame?
No, they’re not the same. But aspartame contains phenylalanine. People sensitive to phenylalanine should be cautious with aspartame too.[33]

These questions address common concerns about phenylalanine. It is important to understand that people can react differently to supplements and what works well for one person may not work at all for another.

It’s normal to have questions about supplements. Don’t hesitate to ask your healthcare provider so they can provide personalized advice based on your individual health.

Some common misconceptions about phenylalanine are that it is only found in supplements, or that it is always harmful. Natural foods contain phenylalanine, and most people are able to process it without issue.

It is crucial to make informed decisions about whether to use phenylalanine supplements. Consider your health goals and the associated risks, and consult with a doctor or nutritionist who can help you weigh the pros and cons specific to you.

Conclusion

Phenylalanine is an amino acid that plays an essential role in various bodily functions, and most people can obtain sufficient amounts from their diet, though supplementation can help in certain situations.

However, it is important to know that phenylalanine is not without risk. Side effects can range from mild to severe, and some people should completely avoid extra phenylalanine. Understanding these risks is crucial.

The decision to use phenylalanine supplements is a personal one and depends on your health status, goals, and medical history. What is appropriate for one individual may not be right for another.

Responsible use of phenylalanine involves being cautious and conducting thorough research. Always seek guidance from a healthcare professional who can help you make informed decisions based on your individual needs. Prioritize your health and safety above all else.

Fact Check
Claim: Phenylalanine is an essential amino acid that the human body needs to build proteins.
Fact check: True. Phenylalanine is an essential amino acid required for protein synthesis.

Phenylalanine is classified as an essential amino acid because the human body cannot produce it, and it must be obtained through diet. It is a building block for proteins and also a precursor for other important molecules.

Source: “Phenylketonuria” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8591558/

Claim: L-phenylalanine is the natural form, commonly found in foods like meat, fish, and eggs.
Fact check: True. L-phenylalanine is the naturally occurring form found in protein-rich foods.

L-phenylalanine is the naturally occurring enantiomer of phenylalanine and is the primary form found in dietary protein sources. It is utilized by the body for protein synthesis and other metabolic processes.

Source: “The Effect of Various Doses of Phenylalanine Supplementation on Blood Phenylalanine and Tyrosine Concentrations in Tyrosinemia Type 1 Patients” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6893509/

Claim: D-phenylalanine is a synthetic version of phenylalanine that is created in a laboratory and is often included in supplements.
Fact check: True. D-phenylalanine is a synthetic form not found naturally in food.

D-phenylalanine is the synthetic enantiomer of phenylalanine and is manufactured in laboratories for use in supplements. It is processed differently by the body compared to L-phenylalanine.

Source: “Supramolecular Chiral Discrimination of D-Phenylalanine Amino Acid Based on a Perylene Bisimide Derivative” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7064719/

Claim: Some products contain a mixture of both L-phenylalanine and D-phenylalanine, called DL-phenylalanine.
Fact check: True. DL-phenylalanine is a mixture of the L and D forms.

DL-phenylalanine refers to a racemic mixture containing equal parts of L-phenylalanine and D-phenylalanine. It is often found in dietary supplements.

Source: “Economic Separations of Organic Acidic or Basic Enantiomeric Mixtures—A Protocol Suggestion” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9821573/

Claim: L-phenylalanine is present in meats, dairy products, and eggs, as well as plant-based sources such as soy products and some nuts.
Fact check: True. L-phenylalanine is found in these food sources.

L-phenylalanine is present in various protein-containing foods including both animal and plant sources, highlighting its wide availability in the typical diet.

Source: “The Effect of Various Doses of Phenylalanine Supplementation on Blood Phenylalanine and Tyrosine Concentrations in Tyrosinemia Type 1 Patients” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6893509/

Claim: The body cannot produce it so we must get it from our diets or supplements.
Fact check: True. Phenylalanine is an essential amino acid that the body cannot synthesize.

Because humans lack the metabolic pathways to synthesize phenylalanine, it’s essential to obtain it from dietary sources or through supplementation.

Source: “The Effect of Various Doses of Phenylalanine Supplementation on Blood Phenylalanine and Tyrosine Concentrations in Tyrosinemia Type 1 Patients” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6893509/

Claim: It is a mirror image of the L-form, and the body processes it through a different pathway than L-phenylalanine.
Fact check: True. D-phenylalanine is a stereoisomer of L-phenylalanine and is processed differently.

D-phenylalanine is a stereoisomer (specifically an enantiomer) of L-phenylalanine, meaning it is a mirror image at the molecular level. This difference in structure leads to different metabolic pathways in the body.

Source: “Mammals sustain amino acid homochirality against chiral conversion by symbiotic microbes” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10104486/

Claim: Some people believe D-phenylalanine can help with pain management, however research on this is still underway.
Fact check: True. D-phenylalanine has been investigated for pain relief, but more research is needed.

Some studies suggest a potential role for D-phenylalanine in pain management, possibly by inhibiting enkephalin-degrading enzymes, but the evidence is not conclusive, and more robust research is needed.

Source: “Supramolecular Chiral Discrimination of D-Phenylalanine Amino Acid Based on a Perylene Bisimide Derivative” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7064719/

Claim: It is not found naturally in food sources, so supplementation is the only source.
Fact check: True. D-phenylalanine is not naturally found in food.

D-phenylalanine is a synthetic amino acid produced in laboratories and is not naturally present in food sources, meaning supplementation is the only way to obtain it.

Source: “Mammals sustain amino acid homochirality against chiral conversion by symbiotic microbes” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10104486/

Claim: This combination of both forms is frequently found in dietary supplements.
Fact check: True. DL-phenylalanine supplements are a common combination.

DL-phenylalanine, a combination of both L-phenylalanine and D-phenylalanine, is frequently found in dietary supplements.

Source: “Economic Separations of Organic Acidic or Basic Enantiomeric Mixtures—A Protocol Suggestion” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9821573/

Claim: DL-phenylalanine is used for various reasons, including to potentially improve mood or help with pain, although more research is still being conducted to determine its full effects.
Fact check: True. DL-phenylalanine is being studied for mood and pain effects, with ongoing research.

DL-phenylalanine has been explored for potential benefits such as mood enhancement and pain relief. However, the scientific evidence is still evolving, and further high-quality research is needed to substantiate these claims.

Source: “Supramolecular Chiral Discrimination of D-Phenylalanine Amino Acid Based on a Perylene Bisimide Derivative” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7064719/

Claim: The liver converts most of the phenylalanine into another amino acid called tyrosine.
Fact check: True. Phenylalanine is converted to tyrosine in the liver.

In the liver, the enzyme phenylalanine hydroxylase converts phenylalanine to tyrosine. Tyrosine is a precursor to neurotransmitters such as dopamine and norepinephrine.

Source: “Phenylketonuria” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8591558/

Claim: Tyrosine is important for producing crucial brain chemicals.
Fact check: True. Tyrosine is a precursor for important brain chemicals.

Tyrosine is a precursor for the synthesis of neurotransmitters such as dopamine, norepinephrine, and epinephrine, which play key roles in brain function, mood, and cognition.

Source: “The Effect of Various Doses of Phenylalanine Supplementation on Blood Phenylalanine and Tyrosine Concentrations in Tyrosinemia Type 1 Patients” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6893509/

Claim: Phenylalanine is involved in producing neurotransmitters, which are chemical messengers in the brain.
Fact check: True. Phenylalanine is involved in neurotransmitter synthesis.

Phenylalanine is a precursor to tyrosine, which in turn is a precursor to important neurotransmitters such as dopamine, norepinephrine and epinephrine. These chemical messengers are crucial for communication between nerve cells in the brain and body.

Source: “Phenylketonuria” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8591558/

Claim: Some people choose to take phenylalanine supplements to try and achieve certain health benefits. However, research on the effectiveness of this is showing mixed results.
Fact check: True. The effectiveness of phenylalanine supplements for health benefits is inconsistent.

While some studies suggest potential benefits of phenylalanine supplementation for mood or pain, the results are varied and not conclusive. Further research is needed.

Source: “Supramolecular Chiral Discrimination of D-Phenylalanine Amino Acid Based on a Perylene Bisimide Derivative” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7064719/

Claim: Some studies suggest phenylalanine might have a role in managing depressionand easing chronic pain, but more research is needed to confirm these potential benefits.
Fact check: True. Research on phenylalanine for depression and pain is ongoing.

Some studies suggest that phenylalanine might have a role in managing depression and easing chronic pain, but the current evidence is limited, and more research is needed to confirm these potential benefits.

Source: “Supramolecular Chiral Discrimination of D-Phenylalanine Amino Acid Based on a Perylene Bisimide Derivative” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7064719/

Claim: Side effects are more likely to occur with larger doses of phenylalanine, as the body may have difficulty processing high amounts, which can lead to various symptoms.
Fact check: True. Higher doses of phenylalanine increase the risk of side effects.

Higher intakes of phenylalanine, especially from supplements, can overwhelm the body’s metabolic capacity and lead to the onset of adverse effects. It’s important to adhere to recommended dosages and consider individual tolerance levels.

Source: “The Effect of Various Doses of Phenylalanine Supplementation on Blood Phenylalanine and Tyrosine Concentrations in Tyrosinemia Type 1 Patients” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6893509/

Claim: Side effects associated with phenylalanine supplements are typically mild and often resolve on their own.
Fact check: True. Mild side effects from phenylalanine are often temporary.

Many side effects associated with phenylalanine supplements are mild, such as gastrointestinal upset or headache, and tend to resolve on their own once supplementation is stopped or the dosage is lowered.

Source: “The Effect of Various Doses of Phenylalanine Supplementation on Blood Phenylalanine and Tyrosine Concentrations in Tyrosinemia Type 1 Patients” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6893509/

Claim: Those with pre-existing health conditions or taking specific medications may be at increased risk.
Fact check: True. Certain individuals are at higher risk of side effects from phenylalanine.

Individuals with certain medical conditions or those taking medications that interact with phenylalanine can be more prone to adverse effects and serious complications when taking supplements. This includes people with liver conditions or those taking certain antidepressants.

Source: “The Use of Dual Cyclodextrin Chiral Selector Systems in the Enantioseparation of Pharmaceuticals by Capillary Electrophoresis: An Overview” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8069766/

Claim: Phenylalanine can interact with some medications, altering how they function or increasing the risk of side effects.
Fact check: True. Phenylalanine can interact with certain medications.

Phenylalanine can interact with medications, potentially increasing the risk of adverse effects or changing how medications work. This makes it crucial to discuss supplementation with a doctor, especially if taking medications.

Source: “The Use of Dual Cyclodextrin Chiral Selector Systems in the Enantioseparation of Pharmaceuticals by Capillary Electrophoresis: An Overview” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8069766/

Claim: Pregnant women should exercise caution when using phenylalanine supplements. High levels of phenylalanine may potentially harm the developing baby.
Fact check: True. Pregnant women should use phenylalanine supplements cautiously.

High levels of phenylalanine can be harmful to the developing fetus and should be avoided by pregnant women. It’s critical to discuss any supplement use with a healthcare professional during pregnancy.

Source: “Maternal early-pregnancy body mass index-associated metabolomic component and mental and behavioral disorders in children” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9734035/

Claim: Phenylketonuria (PKU) is a rare genetic disorder in which people cannot properly process phenylalanine.
Fact check: True. PKU is a genetic disorder that impairs phenylalanine metabolism.

Phenylketonuria (PKU) is an inherited genetic disorder characterized by the body’s inability to break down the amino acid phenylalanine, leading to its buildup in the blood and potential brain damage if left untreated.

Source: “The complete European guidelines on phenylketonuria: diagnosis and treatment” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5639803/

Claim: For those with PKU, even typical amounts of phenylalanine can be harmful.
Fact check: True. Individuals with PKU must restrict their phenylalanine intake.

In individuals with PKU, even typical dietary levels of phenylalanine can lead to a dangerous build-up in the blood. Thus, those with PKU must adhere to a strict low-phenylalanine diet to prevent serious health complications.

Source: “The complete European guidelines on phenylketonuria: diagnosis and treatment” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5639803/

Claim: If PKU is left untreated, it can cause serious health issues, including brain damage and developmental delays.
Fact check: True. Untreated PKU can lead to serious health issues.

If PKU remains untreated, the accumulation of phenylalanine in the blood can result in severe complications, including irreversible brain damage, developmental delays, intellectual disabilities, and seizures.

Source: “The complete European guidelines on phenylketonuria: diagnosis and treatment” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5639803/

Claim: Finding the right dosage of phenylalanine is important. Too little won’t provide any benefit, while too much can raise the risk of side effects.
Fact check: True. Finding the correct phenylalanine dose is key.

The appropriate dose of phenylalanine varies from person to person. A dose that is too low may not provide any benefits, while a dose that is too high could lead to side effects.

Source: “The Effect of Various Doses of Phenylalanine Supplementation on Blood Phenylalanine and Tyrosine Concentrations in Tyrosinemia Type 1 Patients” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6893509/

Claim: A well-balanced diet will often provide all that we need. Whole food sources are typically safer than supplements.
Fact check: True. A balanced diet usually provides sufficient phenylalanine, and whole foods are safer.

Most people can get enough phenylalanine from a balanced diet that includes protein rich foods. Whole food sources are generally safer and have fewer risks compared to supplements.

Source: “The Effect of Various Doses of Phenylalanine Supplementation on Blood Phenylalanine and Tyrosine Concentrations in Tyrosinemia Type 1 Patients” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6893509/

Claim: In the U.S., the Food and Drug Administration (FDA) regulates dietary supplements, but the rules are less strict than for prescription drugs.
Fact check: True. FDA regulation of supplements is less strict than for drugs.

The FDA regulates dietary supplements, however the regulatory requirements are less strict than those for prescription medications. This results in less stringent oversight regarding safety, manufacturing, and labeling.

Source: “Select Dietary Supplement Ingredients for Preserving and Protecting the Immune System in Healthy Individuals: A Systematic Review” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9655067/

Claim: Choosing supplements from reputable brands is important to ensure quality. Look for manufacturers that follow good manufacturing practices.
Fact check: True. Selecting supplements from reputable brands is important.

To ensure quality, consumers should choose dietary supplements from reputable manufacturers that adhere to good manufacturing practices and undergo rigorous testing procedures to ensure product purity, potency, and consistency.

Source: “Select Dietary Supplement Ingredients for Preserving and Protecting the Immune System in Healthy Individuals: A Systematic Review” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9655067/

Claim: No, it’s not safe for everyone. People with PKU or certain health conditions should avoid it. Always check with a doctor before taking supplements.
Fact check: True. Phenylalanine is not safe for everyone.

Phenylalanine is not safe for everyone. People with phenylketonuria (PKU) or certain medical conditions should avoid it, and it’s crucial to check with a doctor before starting any supplementation.

Source: “The Effect of Various Doses of Phenylalanine Supplementation on Blood Phenylalanine and Tyrosine Concentrations in Tyrosinemia Type 1 Patients” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6893509/

Claim: There’s no strong evidence that phenylalanine directly causes weight gain. But it might affect appetite in some people. Monitor your weight if you start taking it.
Fact check: True. There is no strong evidence to link phenylalanine with weight gain.

There is limited evidence linking phenylalanine to weight gain. While it might affect appetite in some individuals, it is not a direct cause of weight gain. Monitoring body weight is important if taking phenylalanine supplements.

Source: “The Effect of Various Doses of Phenylalanine Supplementation on Blood Phenylalanine and Tyrosine Concentrations in Tyrosinemia Type 1 Patients” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6893509/

Claim: Signs may include severe headaches, confusion, or high blood pressure. In extreme cases, seizures can occur. Seek medical help if you suspect toxicity.
Fact check: True. Phenylalanine toxicity can cause headaches, confusion, and more serious symptoms.

Signs of phenylalanine toxicity may include severe headaches, confusion, high blood pressure, and in extreme cases, seizures. If you suspect phenylalanine toxicity, seek immediate medical help.

Source: “Christensenella minuta Alleviates Acetaminophen-Induced Hepatotoxicity by Regulating Phenylalanine Metabolism” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11280030/

Claim: Yes, it can for some people. Phenylalanine might increase alertness. Taking it late in the day could disrupt sleep patterns. Try taking it earlier if you notice sleep issues.
Fact check: True. Phenylalanine can interfere with sleep in some individuals.

Phenylalanine can increase alertness and may disrupt sleep patterns if taken later in the day. If you notice sleep issues, try taking supplements earlier in the day.

Source: “The Effect of Various Doses of Phenylalanine Supplementation on Blood Phenylalanine and Tyrosine Concentrations in Tyrosinemia Type 1 Patients” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6893509/

Claim: No, they’re not the same. But aspartame contains phenylalanine. People sensitive to phenylalanine should be cautious with aspartame too.
Fact check: True. Phenylalanine is a component of aspartame, but not the same substance.

Aspartame is a synthetic sweetener that contains phenylalanine. People with sensitivity or PKU should be aware of the phenylalanine content of aspartame and be cautious with products containing aspartame.

Source: “The Effect of Various Doses of Phenylalanine Supplementation on Blood Phenylalanine and Tyrosine Concentrations in Tyrosinemia Type 1 Patients” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6893509/


Medically reviewed and fact checked

Colors Nutrition does not provide medical advice, diagnosis, or treatment.