Glytactin Restore Powder, Berry, 73 Calories Each. For the dietary management of phenylketonuria (PKU). Dispensed by prescription. Glytactin RESTORE Powder- Berry is a medical food for patients with PKU, ages one year and older. Each packet contains 5 grams of Glytactin protein and when added to water makes a great tasting fruit-flavored rehydration drink.