The body needs phenylalanine for this

The special amino acid phenylalanine is involved in many bodily processes. Find out everything you need to know about its effects, how to cover your requirements with food and in which cases supplementation makes sense.

What is phenylalanine?

Phenylalanine is a proteinogenic amino acid, which means that it is a protein building block and plays an important role in living organisms. There are two forms:

L-phenylalanine: This is the naturally occurring form and is an essential amino acid. This means that the body cannot produce it itself and it must therefore be obtained from food. L-phenylalanine plays an important role in the synthesis of dopamine, noradrenaline and serotonin in the brain.

D-phenylalanine: This is a mirror image form of phenylalanine that is less common in the body. It is sometimes used for medicinal purposes as it can have an effect on pain regulation.

In this article we have summarised everything you need to know about amino acids and their benefits, as well as more information.

Is phenylalanine healthy?

Yes, it is an essential amino acid and plays an important role in the human organism. In appropriate amounts, it is healthy and necessary for various biological processes.

What is phenylalanine good for?

L-phenylalanine is good for the body in many ways and plays important roles in various physiological processes.

Protein biosynthesis: As an essential amino acid, it is essential for the formation of proteins - they are the building blocks of life and play a crucial role in tissue formation and repair, enzyme function and many other vital processes.

Neurotransmitters: It is converted into dopamine, noradrenaline and serotonin in the brain. These neurotransmitters are crucial for the regulation of mood, sleep, emotional well-being and cognitive processes [1].

Energy source: It can also be used as an energy source, especially when the body needs extra energy. It can be converted into glucose to meet energy needs [2].

Antioxidant properties: It contributes to the formation of antioxidants, which can protect the body from oxidative stress and free radical damage [3].

However, it is important to note that excessive consumption, especially in the form of supplements, can cause health problems. Most people get sufficient amounts of this amino acid from a varied diet that includes meat, fish, eggs, dairy products, nuts and seeds.

What happens if you don't have enough phenylalanine?

A deficiency can have negative effects on health, as it is an essential amino acid that the body cannot produce itself and must therefore be obtained from the diet. If you do not have enough phenylalanine-rich foods in your diet, various health problems can occur, including:

Delayed growth: A deficiency, for example due to a PKU disorder, can lead to delayed growth and impaired development [4].

Fatigue and weakness: It is used to generate energy. A deficiency can lead to fatigue and general weakness [2].

Brain disorders: It is also a precursor of dopamine and serotonin. A deficiency can lead to neurological problems that affect mood and cognitive function [1].

It is important to emphasise that a severe deficiency of phenylalanine is usually rare, as most people get sufficient amounts of this amino acid from a varied diet of protein-rich foods.

What foods contain phenylalanine?

It is found in a variety of foods, and is particularly high in protein-rich foods. Here are some foods that are good sources of phenylalanine:

Animal proteins: Meat, poultry, fish and seafood are rich in this particular amino acid. These foods are not only good sources of phenylalanine, but also provide other essential amino acids.

Dairy products: Milk, yoghurt, cheese and other dairy products are also good sources of phenylalanine. These foods also provide calcium and other important nutrients.

Eggs: Eggs are an excellent source of phenylalanine and are also high in many other essential nutrients.

Pulses: Pulses such as beans, lentils and peas are also rich in phenylalanine.

Soy: Tofu and other soya products are other plant-based protein-rich foods that are good sources of phenylalanine.

Nuts and seeds: Almonds, walnuts, pistachios, sunflower seeds, and other nuts and seeds also contain healthy fats and fibre.

A balanced diet that offers a variety of different foods will help ensure that you get enough of all the essential amino acids.

Why can't phenylalanine be broken down?

The amino acid phenylalanine can normally be broken down in the body, but there are certain genetic disorders that cause it to not be broken down properly. One such disorder is phenylketonuria (PKU), which is due to a genetic defect in an enzyme called phenylalanine hydroxylase.

Normally, the amino acid L-phenylalanine is converted to tyrosine in the liver by the enzyme phenylalanine hydroxylase. Tyrosine is another amino acid that is required for various physiological functions in the body. In PKU sufferers, the phenylalanine hydroxylase enzyme does not function properly or is completely absent, which means that phenylalanine is not sufficiently converted into tyrosine in the bloodstream.

All about Effect of L-Tyrosine and more information can be found in this article for you.

The amino acid then accumulates in the blood and reaches toxic concentrations. This can lead to severe neurological problems, especially in children whose brains are still developing. Without proper treatment, PKU can lead to multiple health problems.

The main treatment for PKU consists of a strictly controlled low-phenylalanine diet. Specific foods and supplements containing phenylalanine must be used to ensure that they consume sufficient tyrosine and other important nutrients while limiting phenylalanine. By following this diet, the toxic effects in the body can be minimised, supporting the long-term health of those affected.

When to take phenylalanine supplements?

Taking such supplements should usually be done under a doctor's supervision and should only be considered in certain medical situations. In most cases, it is not necessary to use L-phenylalanine as a dietary supplement, as most people get sufficient amounts of this amino acid from their normal diet. However, there are some situations in which L-phenylalanine capsules may be considered:

Nutritional therapy: In certain medical situations where the need for amino acids is increased, a doctor may recommend L-phenylalanine capsules. For example, this may be the case for people with severe burns, trauma or during recovery after certain surgical procedures.

Neurological conditions: In some cases, L-phenylalanine may be considered as a dietary supplement to treat certain neurological conditions. However, use for the treatment of neurological conditions should only be done under medical supervision [5].

It is important that you do not take L-phenylalanine capsules (such capsules usually contain between 500 mg and 1000 mg) without a doctor's recommendation, as excessive phenylalanine intake can cause health problems. The daily dosage and need for phenylalanine supplements should always be assessed by a qualified doctor or dietitian who will take into account your individual needs and medical conditions.

How many milligrams of phenylalanine are recommended per day?

The recommended daily intake of L-phenylalanine for adults over 19 years of age is 25 mg per kilogram of body weight [6].

The actual amount of L-phenylalanine you need each day may vary depending on your age, gender, activity level and other individual factors. However, it's important to focus on eating a balanced diet that includes enough protein from a variety of sources to ensure you're getting enough of the amino acid phenylalanine and other amino acids.

Sources:

[1] https://www. sciencedirect.com/topics/neuroscience/phenylalanine
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7353198/
[3] https://www.eurekaselect.com/article/92678
[4] https://pubmed.ncbi.nlm.nih.gov/29089407/
[5] https://www.intechopen.com/chapters/71337
[6] https://www.cambridge.org/core/journals/british-journal-of-nutrition/article/recent-advances-in-determining-protein-and-amino-acid-requirements-in-humans/FBFB18EF9B97F7ED3EF92910D6CE4E57