Phenylalanine is a type of amino acid. Amino acids are molecules that combine to form proteins.
Phenylalanine is an essential amino acid, which means the body cannot synthesize its own phenylalanine. Instead, humans must obtain phenylalanine from the foods they eat.
Phenylalanine is a component of several important proteins and enzymes. For example, the body can convert phenylalanine into tyrosine, which is then used to synthesize the neurotransmitters dopamine and norepinephrine.
Phenylalanine also plays a role in the production of other important amino acids.
It is safe for most people, except people with phenylketonuria, who may not be able to break it down.
There are two types of phenylalanine: L-type and D-type. These different forms have different functions in the body. The L-form is incorporated into the protein, while the D-form acts as an analgesic.
L-Phenylalanine occurs naturally in certain foods, while D-Phenylalanine is a synthetic variant of L-Phenylalanine.
Your body uses L-phenylalanine to make proteins and other important molecules. It has also been studied to treat a variety of conditions, including skin conditions and depression.
However, for people with the genetic disorder phenylketonuria (PKU), this can be dangerous because it impairs the body's ability to metabolize phenylalanine.
Important for many body functions
Your body needs phenylalanine and other amino acids to make proteins, which are found in your brain, blood, muscles, gut, and almost everywhere else in your body.
Phenylalanine is also critical for the production of other molecules, including:
- Tyrosine. This amino acid is produced directly from phenylalanine. Your body uses it to make new proteins or convert it into other molecules like adrenaline.
- Epinephrine and norepinephrine. These molecules are critical to your body's fight or flight response when you experience stressful situations.
- Dopamine. This neurotransmitter is an important component of the brain's reward center and is involved in motor control, memory, and learning.
Dysfunction of these molecules may lead to negative health effects, such as depression.
In fact, because your body uses amphetamine to make these molecules, its association with major depression has been studied.
Benefits of Phenylalanine
Several studies have examined how phenylalanine may be beneficial in treating certain diseases.
Some studies suggest that taking phenylalanine supplements and ultraviolet (UV) light therapy may improve skin pigmentation in people with vitiligo, a skin disease that causes the skin to lose pigment.
Phenylalanine is also used to produce dopamine, a molecule that plays a key role in mental health and depression.
In a small, older study conducted in 1977 that included 12 people with depression, two-thirds of the participants improved their symptoms after taking a mixture of D- and L-type amino acids.
Newer research has similarly found that low levels of phenylalanine may be linked to major depression.
On the other hand, other older studies have shown no clear benefit. Ultimately, because recent research on the effects of amphetamine on depression is limited, more high-quality research is needed.
In addition to vitiligo and depression, amphetamine has also been studied for its potential effects on:
- pain. Some earlier studies have found that D-phenylalanine may relieve pain, but overall, the results are mixed.
- Quit drinking. According to a 2011 study, using supplements containing D-phenylalanine and other amino acids can help relieve alcohol withdrawal symptoms.
- Parkinson's Disease. An earlier study suggests that phenylalanine may support the treatment of Parkinson's disease, but more research is needed. Although the jury is still out, tyrosine's effects on brain function and Parkinson's disease have also been studied.
- ADHD. Currently, research does not show any benefit from this amino acid in treating attention deficit hyperactivity disorder (ADHD).
Dangers and Side Effects
Phenylalanine is found in many protein-containing foods and is generally considered safe by the U.S. Food and Drug Administration (FDA).
Levels naturally occurring in foods may not pose a risk to healthy individuals. What's more, few or no side effects are typically observed at supplemental doses of up to 12 grams per day.
Still, it's best to only use phenylalanine as directed and consult your doctor before adding any supplements to your routine.
People taking medications for schizophrenia should avoid amphetamine because it may worsen symptoms of tardive dyskinesia, a disorder characterized by involuntary repetitive movements .
People who are pregnant or breastfeeding should also avoid taking phenylalanine supplements because there is limited research on its safety and potential long-term effects.
Additionally, patients with phenylketonuria (PKU) should carefully monitor their amino acid intake. This disorder impairs the body's ability to metabolize phenylalanine, resulting in elevated levels of phenylalanine in the blood.
Dangerously high blood levels of phenylalanine can cause severe brain damage, growth retardation, intellectual disability, and other problems with the transport of amino acids to the brain.
PKU has also been linked to several other conditions, including epilepsy, hyperreflexia, and neurological problems such as convulsions or tremors. Because of the seriousness of the disease, newborns are usually screened soon after birth.
People with PKU are placed on a special low-protein diet to limit their intake of phenylalanine, which is usually maintained for life.
pregnancy and childbirth
A 2015 reviewTrusted Source noted that women with PKU are more likely to have children with PKU. Healthcare professionals call this maternal PKU syndrome.
According to the review, babies of mothers with PKU syndrome are more likely to have the following health problems:
- heart defect
- microcephaly
- cognitive impairment
- intrauterine growth restriction
Foods high in phenylalanine
Phenylalanine is found in many high-protein plant and animal foods, including meat, fish, poultry, and legumes.
It's also found in aspartame, an artificial sweetener commonly added to diet soda and many sugar-free foods.
Here are some major food sources of phenylalanine:
- Meat: beef, pork, lamb, venison
- Poultry: chicken, turkey, duck, goose
- Seafood: salmon, trout, tuna, mackerel, shrimp, lobster
- Eggs: whole eggs, egg whites
- Dairy products: milk, cheese, yogurt
- Nuts: almonds, pistachios, macadamia nuts, cashews, walnuts
- Seeds: pumpkin seeds, pumpkin seeds, hemp seeds, sunflower seeds
- Nut butters: peanut butter, almond butter, cashew butter
- Legumes: lentils, chickpeas, black beans, kidney beans
- Whole grains: quinoa, oats, rye, barley, wheat
- Soy products: soybeans, tofu, tempeh, edamame, protein supplements
Weight loss products: Diet soda and sugar-free ice cream, gum, candy and flavored yogurt made with aspartame Generally speaking, you don't need to choose foods based on their phenylalanine content. Instead, eating a variety of protein-rich foods throughout the day will provide you with all the phenylalanine and other essential amino acids and nutrients you need.
Optimal dosage
An earlier review from 2007 suggested that the minimum daily dose of amphetamine was approximately 9.1 milligrams per kilogram of body weight (mg/kg). According to the review, the maximum daily dose of phenylalanine is 38-48 mg/kg of body weight.
People with PKU need to consume much less phenylalanine than people without the disease. People with PKU should consult a doctor or nutritionist for further advice regarding phenylalanine intake.
generalize
Phenylalanine is an essential amino acid found in plant and animal foods.
It may benefit the skin disease vitiligo, but research on its effects on depression, pain and other conditions is limited.
While it's generally considered safe for healthy people, it's important for people with phenylketonuria (PKU) to keep intake low to avoid potentially dangerous side effects.
If you notice any negative side effects after taking phenylalanine supplements or eating high-protein foods, talk to your doctor.
They can test your blood amino acid levels and help determine the best treatment option for you.
