PowerBar Protein Plus. 30g Protein. Made with TriSource Protein 3.5g Leucine, a key driver of muscle growth. Supports Muscle Growth and Helps Reduce Muscle Breakdown: Protein plays an essential role in the growth, maintenance and repair of muscles. Studies show that consuming protein before and after exercise helps build lean muscle and aids muscle recovery. ProteinPlus is the only protein bar made with TriSource Protein, PowerBar's proprietary three protein blend. TriSource combines whey, soy and casein proteins which are absorbed by the body at different rates to deliver a steady supply of muscle building amino acids to support muscle growth and help reduce muscle breakdown. With Leucine, The Key Amino Acid For Muscle Building: Leucine has been shown in studies to serve a key role in muscle protein synthesis. ProteinPlus with 30g of protein contains 3.5g of leucine, the essential amino acid that directly stimulates muscle protein synthesis.