Branched-chain amino acids are essential amino acids which your body can't produce, so you must get them from food. The branched-chain amino acids (BCAA) are a group of three essential amino acids: leucine, isoleucine and valine. They are essential, meaning they can't be produced by your body and must be obtained from food. BCAA supplements have been shown to build muscle, decrease muscle fatigue and alleviate muscle soreness.