Phenylalanine is an amino acid found in many proteins in the body (tissues, hormones, bones, etc.). These proteins are also present in many of the foods we eat. Phenylketonuria is a hereditary metabolic disease, usually diagnosed at birth, characterized by an inability by the body to effectively process phenylalanine. If a low-phenylalanine diet is not initiated in the early weeks of life, phenylalanine levels build up in the child's blood, causing significant brain damage. By managing phenylalanine levels through diet, children can develop normally.
Principles of a low-phenylalanine diet
The diet consists in tyrosine supplementation and restricting the intake of phenylalanine. The idea behind the diet is to consume only the amount of phenylalanine that is necessary for normal growth and body processes, but no more.
It is also important to ensure an adequate intake of protein and energy to promote normal growth. The optimal amount of phenylalanine varies from person to person. Regular monitoring of blood levels is crucial for achieving balance. It is also important to ensure adequate energy intake to prevent protein destruction and the subsequent release of phenylalanine into the blood. A low-phenylalanine diet is a life-long commitment.
Foods to eat and foods to avoid
In newborns, the diet should consist of a modified amino acid formula that contains little or no phenylalanine. Ingesting minute amounts (calculated by a nutritionist) of regular formula or breast milk can help meet minimum phenylalanine needs.
Foods containing small amounts of phenylalanine can then be introduced. For example, certain food products such as sugar, jam, vegetable oil and some fruits and vegetables can be consumed at will. However, only small quantities of other fruits and vegetables (potatoes and Brussels sprouts, for example) should be eaten. Bread, pasta, rice and cereal should be eaten in moderation.
There are special nutritional products on the market that contain protein hydrolysates from which phenylalanine has been partially or completely removed. For those who must adhere to a low-phenylalanine diet, these products are part of everyday life since they contain essential vitamins, minerals and proteins.
The following foods are examples of products that should be avoided:
- Products or drugs that contain aspartame (diet sodas, artificial sweeteners, etc.)
It goes without saying that it is important to seek expert advice from health care professionals including nutritionists and physicians. Regular consultations with your specialists will allow you to adapt your diet to your particular condition and needs.
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The patient information leaflets are provided by Vigilance Santé Inc. This content is for information purposes only and does not in any manner whatsoever replace the opinion or advice of your health care professional. Always consult a health care professional before making a decision about your medication or treatment.