There are 20 different amino acids that make up the thousands of different proteins in the human body. Nine of the 20 are considered essential amino acids, meaning they cannot be made by your body and must be obtained through your diet. Of the nine essential amino acids, three are the branched-chain amino acids (BCAAs): leucine, isoleucine and valine. “Branched-chain” refers to the chemical structure of BCAAs, which are found in protein-rich foods such as eggs, meat and dairy products. They are also a popular dietary supplement sold primarily in powder form.