Properties of phenylalanine

Benefits and functions of phenylalanine, essential amino acid

What is phenylalanine?

Phenylalanine is an essential amino acid that the body can not synthesize and therefore must be provided by the diet. The richest foods in this amino acid are milk and dairy products, meat and fish.

Phenylalanine is a precursor of tyrosine, an amino acid involved in the production of neurohormones and some chemicals such as norepinephrine, tyramine, epinephrine, dopamine, thyroxine, or cholecystokinin (CCK).

The abbreviation for this amino acid is Phe.

Properties of phenylalanine

abel of sweetener aspartame

Photo of a label of sweetener aspartame. The label reads: “Contains phenylalanine”, so it is not suitable for phenylketonuria.

Its functions lie in keeping our brain active, producing chemical messages through neurotransmitters, promoting learning and memory. The levels of phenylalanine in the blood and cerebrospinal fluid remain virtually constant throughout life.

It is also responsible for maintaining a good mood managing to increase the level of endorphins in our body. Thus, food intake with phenylalanine may help reduce the symptoms of depression and Alzheimer’s.

Phenylalanine and tyrosine are essential to produce thyroxine, a hormone responsible for the proper functioning of the thyroid gland, which controls the body’s metabolism. The deficit produces thyroxine hypothyroidism.

Phenylalanine cooperates, along with tryptophan in appetite control. It does so through the release of cholecystokinin (CCK), an intestinal hormone responsible for sending the signal of satiety after eating.

It has also been found that helps reduce the sensation of pain. Very useful in anomalies such as rheumatoid arthritis, back pain, muscle pain, dysmenorrhea, etc.

Therefore, the deficit may cause various deficiency symptoms, such as proper contribution can minimize such symptoms in some diseases associated with these characteristics.

Phenylalanine is an essential element in the formation of collagen in our body, thus helping to achieve a connective tissue under the right conditions and a good state of our skin. Useful to reduce skin blemishes, freckles or moles.

Types of phenylalanine

Phenylalanine is normally presented in three ways:

– L-Phenylalanine: The most common in food and that one which is usually found in protein supplements.

– D-Phenylalanine: It is mainly used to relieve pain and listless moods, depression, etc.

D L-Phenylalanine: It is a mixture of 50% of the previous two, with the capacity to paralyze some brain enzymes and prevent paralysis of some hormones such as endorphins.

Either way you prefer, it should not be given without a doctor or for more than 2-3 weeks.

Contraindications of phenylalanine

Pregnant women or people suffering from liver and kidney should not take phenylalanine supplements.

– Phenylalanine supplements, in any form, should NOT be taken for more than two or three consecutive weeks.

– This supplement can produce long-term nervous symptoms like headache and/or anxiety.

– Phenylalanine supplements may raise blood pressure by its stimulating production role of epinephrine and norepinephrine, so that is not recommended for people with hypertension, or people with a family history of hypertension.

– People with antidepressant medication and medication for hypertension should not take this amino acid supplement.

– In case of illness should avoid taking supplements of phenylalanine or other amino acid without medical supervision.

Individuals with phenylketonuria should not take this amino acid, nor sources phenylalanine as aspartame, which may be present in products that normally do not contain phenylalanine (jams, biscuits, tabletop sweeteners,…). In this case, they are labeled with the notice or warning: “contains a source of phenylalanine”.

A diet rich in foods that contain lots phenylalanine are not suitable for people with phenylketonuria. PKU is a disease caused by people who can not properly metabolize this amino acid, which causes damage to the body as growth deficit, lesions in the central nervous system, learning disabilities, greater predisposition to kidney stones. Dietary treatment in these patients is to control the intake of this amino acid.

– In the diet for lupus, it is recommended to reduce the intake of this amino acid.

People with cancer should avoid this amino acid supplement without medical advice, especially if suffering melanoma (Phenylalanine is degraded into tyrosine, which in turn stimulates the synthesis of melanin and may affect skin cancer).

Foods containing phenylalanine

Animal foods are those that contain more phenylalanine, for example cheese.

Within plant foods, we include, for example, peanut butter

* More information: Foods rich in phenylalanine

Poor foods in phenylalanine

Foods that contain little phenylalanine are fruits and vegetables (asparagus, potatoes, etc). They also contain phenylalanine, but in a smaller amount than all previous foods

Phenylalanine supplements

Although you can take phenylalanine supplements, it is recommended to cover the needs of this amino acid through a balanced diet. If supplementation, it is appropriate to consultation a specialist before taking it..

* Related information:

Properties of proteins

Proteins formation

Proteins function

Daily proteins needs

Vegetal proteins

How to combine vegetable proteins

List of amino acids in food

Essential amino acids

Nonessential amino acids

Phenylalanine, Isoleucine, Leucine, Lysine, Methionine, Threonine, Tryptophan, Valine

Aspartic acid, Glutaminic acid, Alanine, Arginine, Cysteine, Cystine, Glycine, Hydroxyproline, Proline, Serine, Tyrosine


punto rojoMore information on amino acids.

Written by Editorial Botanical-online team in charge of content writing

19 March, 2019

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