Glytactin Build 20/20, Smooth. 110 calories per 31 gram (1.1 ounce) pouch. For the dietary management of phenylketonuria (PKU). Dispensed by prescription. Glytactin BUILD 20/20 Smooth is a powdered medical food for PKU patients, ages one year and older. Each pouch contains 20 grams of Glytactin protein with GMPure, Cambrooke's lowest Phe glycomacropeptide (GMP) balanced with an optimized blend of amino acids. Nutritionally complete with vitamins and minerals and DHA. Contains probiotics to support digestive health. A neutral, smooth and milky flavor.