Aguiar Protein supplements for fitness, Grala AP, Da Profein RA, Prootein LF, Resistance band exercises FL, Ribeiro Protein supplements for fitness, Da Silva DK, vitness Andrade WB, Balvedi MC. People can easily mix the powder with liquid with a shaker or spoon. This is one of the most commonly asked questions about protein powder. Casein protein powder, such as this from Bulk, is similar to whey protein as it's also derived from milk.