Because the added amino acids are not complete proteins, though, the protein content of a protein powder with added aminos is not what the test claims it to be. For example, a whey protein powder may claim to contain 20 grams of protein per one scoop serving. If they added 5 grams of glycine per serving, then you are only getting 15 grams of actual whey protein and 5 grams of glycine, which would read as 20 grams of protein per serving in the nitrogen test. At least glycine is one of the 20 amino acids used as the building blocks for protein. However, having an extra 5 grams of this non-essential amino acid is not going to do you any real benefit when it comes to muscle growth. So that serving of whey protein is really only 15 grams of actual whey protein per serving.