All proteins are different because they are all unique combinations of varying amounts of 21 different amino acids. What makes one protein source better than another? What is the best measuring stick to compare the value and quality of one protein against the value and quality of another? This video explains why a balanced amino acid profile is critical in being able to use the protein that an athlete ingests. Simply because it is ingested, digested and absorbed does not mean it will or can all be used.