PKU Easy Liquid Ready-To-Drink Orange/Citrus Flavor Yellow, 130 mL, 97.5 Calories Each. PKU Easy Liquid is a flavoured ready-to-drink phenylalanine free protein substitute containing essential and non-essential amino acids, carbohydrate, vitamins, minerals, trace elements and the omega 3 fatty acid DHA. PKU Easy Liquid is suitable to be used in the dietary management of PKU patients age 3 years and above.