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PKU sphere™ is a GMP based, powdered protein substitute which has been supplemented with amino acids. When mixed with water, a low volume drink is created which is suitable to take from 4 years of age; including pregnancy.

PKU sphere™

What is PKU sphere?

Glycomacropeptide (GMP) is a protein source naturally low in phenylalanine and so can provide a change to the amino acids currently used in protein substitutes for PKU.


PKU sphere is available in two sachet sizes;

  • PKU sphere 15- contains the equivalent of 15g of protein and 28mg of phenylalanine.
  • PKU sphere20 – contains the equivalent of 20g of protein and 36mg of phenylalanine.

It also contains all of the vitamins, minerals and trace elements that are needed to meet your or your child’s daily nutritional requirements. Protein substitutes which are based on GMP are often considered more appetising than those based on amino acids, so they are ideal for some people with PKU.

Who is PKU sphere for?

PKU sphere is for children and adults with PKU. It is suitable from 4 years of age and can be taken through childhood into adulthood, including pregnancy. Your dietitian will advise if it is suitable for you or your child to take PKU sphere.

Why has PKU sphere been suggested for me or my child?

As we all grow our nutritional requirements change, and so it is important that protein substitutes for those people with PKU, be tailored to meet these requirements. PKU sphere is such a protein substitute; it can help in meeting you or your child’s protein, vitamin, mineral and trace element requirements.

PKU sphere may also have been suggested because –

  1. You or your child is struggling with the taste of your regular protein substitute.  As PKU sphere is based on GMP, it may taste better than the protein substitute currently being taken.
  2. You or your child are taking too long to drink your protein substitute or feeling too full. PKU sphere15 and 20 are made up with100ml and 120ml only of water respectively. This creates a low volume drink which may be easier and quicker to take.
  3. Your dietitian is concerned about the number of calories you are taking from your current protein substitute. PKU sphere15 and 20 contain just 91kcal and 120kcal respectively per sachet and are the lowest calories GMP based protein substitute available.

How much PKU sphere do I need?

The amount of PKU sphere needed varies from person to person and will depend on a number of factors including age, weight and PKU control. Initially, PKU sphere will likely replace a portion of your current protein substitute and over time, this may increase. Your dietitian will advise exactly how much PKU sphere is appropriate for you or your child each day.

How do I make PKU sphere?

Making up PKU sphere15:

  1. Measure 120 ml (4 fl oz) of cold water into a cup with lid.
  2. Add 1 packet of PKU sphere15.
  3. Secure lid and shake until powder is fully dissolved.


Making up PKU sphere20:

  1. Pour 120ml water into the shaker provided
  2. Add one sachet of PKU sphere20 to the shaker
  3. Shake well and drink.

What flavour is PKU sphere available in?

PKU sphere is available in 5 different flavour options for sphere20 (Red Berry, Vanilla, Chocolate, Banana and Lemon) and 3 different flavour options for sphere15 (Red Berry, Vanilla and Chocolate). You or your child may choose to take the same flavour each time or prefer to have a variety of flavours.


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PKU sphere is a food for special medical purpose, and should be used under medical supervision.

Explorers Club

If you haven’t done so already, why not browse our Vitafriends Explorers Club – an education programme for families managing PKU in the early years.