Tylactin BUILD 20, 20g PE and 100 calories with only 3mg Tyr and 28mg Phe per 1 ounce (28g) packet. Tylactin BUILD 20 is a versatile powdered medical food for TYR available for those on a low tyrosine and phenylalanine diet who are seeking more protein, fewer calories, and less volume. Includes a complete profile of vitamins and minerals and is neutral in flavor to be taken alone or as a way to build up the protein level of other TYR formulas or low protein food items.