PKU Sphere20, Lemon, 35g Packet. 120 calories per packet. Powdered medical food for the dietary management of Phenylketonuria. PKU sphere is Vitaflos first glycomacropeptide (GMP) based medical food and has a GMP-dominant protein source supplemented with amino acids, bringing patients the potential benefits of GMP without any compromise in nutritional profile. Suitable from 6 years of age.