PKU is a genetic disorder that results in the build-up of an amino acid called phenylalanine or phe. Amino acids are the building blocks of protein.
When protein is eaten it is broken down by enzymes into amino acids (there are around 20 different amino acids). Amino acids are needed for a wide variety of functions within the body such as muscle maintenance, growth, repairing cells and tissues as well as making other body proteins and amino acids.
Phe is found in all foods containing protein. In PKU, the build-up of phe is due to the deficiency of an enzyme called phenylalanine hydroxylase. This PAH enzyme helps turn phe into another amino acid called tyrosine. This results in a build-up of phe and low levels of tyrosine. Both amino acids have important roles in the body. The build up of phe together with the reduction in tyrosine will lead to the person developing learning difficulties. The good news is if PKU is managed correctly from birth the development of learning difficulties can be completely avoided.
PKU can be different from person to person. Some people have no or very little PAH enzyme activity– this is referred to as classical or severe PKU. Some individuals have more PAH enzyme activity - this is called moderate or mild PKU. In the case of mild PKU, the term ‘Hyperphenylalanaemia’ (Hyperphe for short) is sometimes used.
For more information on the diet for PKU see Healthy Eating.
The teenage years bridge the gap between childhood to adulthood. This will bring many changes to your body and mind, which may impact on your diet, especially when food has been such a big focus in your life for as long as you can remember.
You may recognise some of the following changes;
Despite these challenges, it is essential that you consume a healthy balanced low protein diet, which includes enough energy and nutrients to grow, be active and generally be the best version of you!
There are significant benefits for you in following the diet;
Despite becoming more independent in your teenage years it is important to remember you are not alone in this. As well as the support of your family, the specialist metabolic team are there to help you as much as they can. They’ll be more than happy to hear your thoughts and ideas on the diet (what you like and dislike, what works for you and what doesn’t) so that they can make the diet fit more around your lifestyle, instead of you having to fit around the diet! During your teenage years you may also move over to an adult metabolic centre and a different metabolic team will take on your care. To ensure this transition is smooth, both teams will communicate. See Taking Control of Your Own Diet for more guidance.