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Home > Vitafriendspku > Your pku journey > Returning To Diet

Returning To Diet

Returning To Diet

You may at some stage have ‘stopped’ your low protein diet and are now “off diet” or following a diet that is significantly less strict than what is required to keep your blood phe levels within the range recommended by the latest guidelines. There may be many reasons why this happened:

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  • You may have been advised many years ago that you no longer needed to stay on the PKU diet.
  • You may have had a trial period “off diet”, felt no different and so decided to continue.
  • You may have gradually drifted away from your diet as other aspects of your life – work, relationships, social life – were given higher priority.
  • You may have suddenly stopped the diet because you got fed up with it.


Whatever the reason, it is never too late to return to the low protein diet.

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Reasons For Returning To The Diet

Just as there are many reasons why individuals come “off diet”, there can be many different reasons why individuals want to go back “on diet”:

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  • You may have become aware that “diet for life” is now recommended.
  • You may be having challenges in life that you feel could be helped by getting your diet in order.
  • You may think that, with improvements in the products available, the diet is now more manageable.
  • You may experience significant changes in life, which have prompted you to return to diet e.g. a new job or promotion, new relationship or starting a family and so you would like to become pregnant.
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The Importance Of 'Diet For Life'

Diet for life is recommended. Some adults do report problems when their phe levels are high and, even in those who report no problems, there is uncertainty over the long-term impact of high phe levels.

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Beyond the metabolic aspects of being “off diet”, there are also nutritional concerns – stopping your PKU diet, without giving thought to how you will meet all your nutritional requirements, can put you at risk of nutritional deficiencies. 

The potential benefits of returning to diet (and the potential risks from not returning to diet) are outlined in depth in our Diet for Life page.

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Recommended Blood Phe Levels
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If you return to diet, the current European guidelines recommend blood phe levels below 600 μmol/l, ideally in the range 120 – 600*μmol/l. Your specialist metabolic team will advise on this as these can differ from centre to centre and person to person.

It may be a long time since your phe levels were below 600 μmol/l but do not let this put you off. With the exception of pregnant women, improvements in diet to reduce your phe levels can be introduced at a pace that suits you.

*In women, phe levels need to be under stricter control and monitored more closely during both pre-conception and pregnancy. For more information on Pregnancy and PKU, click here.

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Returning To Diet - Next Steps
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Your metabolic team will help you return to a low protein diet. If it has been a long time since you saw your metabolic team, ask your GP to refer you to your nearest metabolic centre to help you get started on a low protein diet. The MDDA website is also helpful for information and support for those with PKU.

If you have not been at a clinic appointment for several years, you may be pleasantly surprised by what you find;

  • Several Australian cities now have dedicated adult clinics.
  • More variety and better tasting protein substitutes are available, with improvements in both the amino acid based-protein substitutes and the introduction of new GMP-based ones.
  • Improvements in specially manufactured low protein foods mean they taste better and there is more variety available than years ago. 


The improvements even extend beyond the clinic with social media now connecting individuals with PKU in ways that were not previously possible. The surge in popularity of vegan foods also has benefits for those with PKU as it can sometimes provide greater opportunity to order directly from restaurant menus.  

Even if you decide that a return to diet is not for you (or at least not for the time being), it is strongly recommended that you remain under the care of your metabolic team and attend your appointments. The team will provide expert advice on the new developments coming through in the management of PKU in addition to monitoring your health and well-being so that, if any problems do arise, they can be quickly recognized and acted upon.

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