HCU Express 20, 34 Gram Packet, Unflavored,101 Calories Per Sachet. HCU express is an unflavoured powdered methionine free protein substitute containing essential and non-essential amino acids, carbohydrate, vitamins, minerals and trace elements. HCU express is for use in the dietary management of Homocystinuria (HCU) from 3 years onwards. Dosage and Administration to be determined by the clinician or dietitian and is dependent on the age, body weight and medical condition of the patient.