Glytactin Build 10. 54 Calories Per Packet. For the dietary management of phenylketonuria (PKU). Dispensed by prescription. Glytactin BUILD is a medical food for PKU patients one year and older. Each packet contains 10 grams of Glytactin protein, the optimal blend of glycomacropeptide (GMP) and amino acids, designed to enhance the protein content of a low Phenylalanine (Phe) diet. A neutral tasting versatile powder to be taken alone or incorporated into beverages and low protein foods. Can be a 10 gram low-Phe Glytactin protein booster for any PKU formula. Contains a complete profile of vitamins & minerals as well as probiotics to support digestive health.