MSUD express 15, 25 Gram Packet, Unflavored. MSUD express is a range of unflavored, powdered leucine, isoleucine and valine free protein substitute, containing essential and non-essential amino acids, carbohydrate, vitamins, minerals and trace elements. MSUD express is for use in the dietary management of Maple Syrup Urine Disease (MSUD) from 3 years of age.